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3d79c59118daa15d20933e3f8d9148fde2977d88
openGauss-server/src/common/backend/parser/parse_clause.cpp
dengxuyue 3d79c59118 Misc bugfixes
2021-03-06 12:39:28 +08:00

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/* -------------------------------------------------------------------------
*
* parse_clause.cpp
* handle clauses in parser
*
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/common/backend/parser/parse_clause.cpp
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "knl/knl_variable.h"
#include "miscadmin.h"
#include "access/heapam.h"
#include "catalog/catalog.h"
#include "catalog/heap.h"
#include "catalog/pg_synonym.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "parser/analyze.h"
#include "parser/parsetree.h"
#include "parser/parse_clause.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "parser/parse_relation.h"
#include "parser/parse_target.h"
#include "pgxc/pgxc.h"
#include "rewrite/rewriteManip.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/rel_gs.h"
#include "utils/syscache.h"
/* clause types for findTargetlistEntrySQL92 */
#define ORDER_CLAUSE 0
#define GROUP_CLAUSE 1
#define DISTINCT_ON_CLAUSE 2
static const char* const clauseText[] = {"ORDER BY", "GROUP BY", "DISTINCT ON"};
static void extractRemainingColumns(
List* common_colnames, List* src_colnames, List* src_colvars, List** res_colnames, List** res_colvars);
static Node* transformJoinUsingClause(
ParseState* pstate, RangeTblEntry* leftRTE, RangeTblEntry* rightRTE, List* leftVars, List* rightVars);
static RangeTblEntry* transformTableEntry(
ParseState* pstate, RangeVar* r, bool isFirstNode = true, bool isCreateView = false);
static RangeTblEntry* transformCTEReference(ParseState* pstate, RangeVar* r, CommonTableExpr* cte, Index levelsup);
static RangeTblEntry* transformRangeSubselect(ParseState* pstate, RangeSubselect* r);
static RangeTblEntry* transformRangeFunction(ParseState* pstate, RangeFunction* r);
static TableSampleClause* transformRangeTableSample(ParseState* pstate, RangeTableSample* rts);
static void setNamespaceLateralState(List *l_namespace, bool lateral_only, bool lateral_ok);
static Node* buildMergedJoinVar(ParseState* pstate, JoinType jointype, Var* l_colvar, Var* r_colvar);
static void checkExprIsVarFree(ParseState* pstate, Node* n, const char* constructName);
static TargetEntry* findTargetlistEntrySQL92(ParseState* pstate, Node* node, List** tlist, int clause);
static TargetEntry* findTargetlistEntrySQL99(ParseState* pstate, Node* node, List** tlist);
static int get_matching_location(int sortgroupref, List* sortgrouprefs, List* exprs);
static List* addTargetToGroupList(
ParseState* pstate, TargetEntry* tle, List* grouplist, List* targetlist, int location, bool resolveUnknown);
static WindowClause* findWindowClause(List* wclist, const char* name);
static Node* transformFrameOffset(ParseState* pstate, int frameOptions, Node* clause);
static Node* flatten_grouping_sets(Node* expr, bool toplevel, bool* hasGroupingSets);
static Node* transformGroupingSet(List** flatresult, ParseState* pstate, GroupingSet* gset, List** targetlist,
List* sortClause, bool useSQL99, bool toplevel);
static Index transformGroupClauseExpr(List** flatresult, Bitmapset* seen_local, ParseState* pstate, Node* gexpr,
List** targetlist, List* sortClause, bool useSQL99, bool toplevel);
/*
* @Description: append from clause item to the left tree
* @in pstate: plan state
* @in rte: the RTE to be appended
* @inout top_rte: receives the RTE corresponding to the join tree item
* @inout top_rti: received the rangetable index of the top_rte.
* @inout relnamespace: receives a List of the RTEs exposed as relation names
* @inout containedRels: receives a bitmap set of the rangetable indexes
* @return: the range table reference of the RTE
*/
static RangeTblRef* transformItem(ParseState* pstate, RangeTblEntry* rte, RangeTblEntry** top_rte, int* top_rti,
List** relnamespace)
{
/* assume new rte is at end */
RangeTblRef* rtr = NULL;
int rtindex;
rtindex = list_length(pstate->p_rtable);
if (unlikely(rte != rt_fetch(rtindex, pstate->p_rtable))) {
ereport(ERROR, (errmodule(MOD_OPT), errmsg("check failure with rt_fetch function")));
}
*top_rte = rte;
*top_rti = rtindex;
*relnamespace = list_make1(makeNamespaceItem(rte, false, true));
rtr = makeNode(RangeTblRef);
rtr->rtindex = rtindex;
return rtr;
}
/*
* transformFromClause -
* Process the FROM clause and add items to the query's range table,
* joinlist, and namespaces.
*
* Note: we assume that pstate's p_rtable, p_joinlist, p_relnamespace, and
* p_varnamespace lists were initialized to NIL when the pstate was created.
* We will add onto any entries already present --- this is needed for rule
* processing, as well as for UPDATE and DELETE.
*
* The range table may grow still further when we transform the expressions
* in the query's quals and target list. (This is possible because in
* POSTQUEL, we allowed references to relations not specified in the
* from-clause. PostgreSQL keeps this extension to standard SQL.)
*/
void transformFromClause(ParseState* pstate, List* frmList, bool isFirstNode, bool isCreateView)
{
ListCell* fl = NULL;
/*
* The grammar will have produced a list of RangeVars, RangeSubselects,
* RangeFunctions, and/or JoinExprs. Transform each one (possibly adding
* entries to the rtable), check for duplicate refnames, and then add it
* to the joinlist and namespaces.
*/
foreach (fl, frmList) {
Node* n = (Node*)lfirst(fl);
RangeTblEntry* rte = NULL;
int rtindex;
List* relnamespace = NIL;
n = transformFromClauseItem(
pstate, n, &rte, &rtindex, NULL, NULL, &relnamespace, isFirstNode, isCreateView);
/* Mark the new relnamespace items as visible to LATERAL */
setNamespaceLateralState(relnamespace, true, true);
checkNameSpaceConflicts(pstate, pstate->p_relnamespace, relnamespace);
pstate->p_joinlist = lappend(pstate->p_joinlist, n);
pstate->p_relnamespace = list_concat(pstate->p_relnamespace, relnamespace);
pstate->p_varnamespace = lappend(pstate->p_varnamespace, makeNamespaceItem(rte, true, true));
}
/*
* We're done parsing the FROM list, so make all namespace items
* unconditionally visible. Note that this will also reset lateral_only
* for any namespace items that were already present when we were called;
* but those should have been that way already.
*/
setNamespaceLateralState(pstate->p_relnamespace, false, true);
setNamespaceLateralState(pstate->p_varnamespace, false, true);
}
/*
* setTargetTable
* Add the target relation of INSERT/UPDATE/DELETE to the range table,
* and make the special links to it in the ParseState.
*
* We also open the target relation and acquire a write lock on it.
* This must be done before processing the FROM list, in case the target
* is also mentioned as a source relation --- we want to be sure to grab
* the write lock before any read lock.
*
* If alsoSource is true, add the target to the query's joinlist and
* namespace. For INSERT, we don't want the target to be joined to;
* it's a destination of tuples, not a source. For UPDATE/DELETE,
* we do need to scan or join the target. (NOTE: we do not bother
* to check for namespace conflict; we assume that the namespace was
* initially empty in these cases.)
*
* Finally, we mark the relation as requiring the permissions specified
* by requiredPerms.
*
* Returns the rangetable index of the target relation.
*/
int setTargetTable(ParseState* pstate, RangeVar* relation, bool inh, bool alsoSource, AclMode requiredPerms)
{
RangeTblEntry* rte = NULL;
int rtindex;
/* Close old target; this could only happen for multi-action rules */
if (pstate->p_target_relation != NULL) {
heap_close(pstate->p_target_relation, NoLock);
}
/*
* Open target rel and grab suitable lock (which we will hold till end of
* transaction).
*
* free_parsestate() will eventually do the corresponding heap_close(),
* but *not* release the lock.
*/
pstate->p_target_relation = parserOpenTable(pstate, relation, RowExclusiveLock, true, false, true);
/*
* Now build an RTE.
*/
rte = addRangeTableEntryForRelation(pstate, pstate->p_target_relation, relation->alias, inh, false);
pstate->p_target_rangetblentry = rte;
/* assume new rte is at end */
rtindex = list_length(pstate->p_rtable);
Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
/*
* Restrict DML privileges to pg_authid which stored sensitive messages like rolepassword.
* there are lots of system catalog and restrict permissions of all system catalog
* may cause too much influence. so we only restrict permissions of pg_authid temporarily
*
* Restrict DML privileges to gs_global_config which stored parameters like bucketmap
* length. These parameters will not be modified after initdb.
*/
if (IsUnderPostmaster && !g_instance.attr.attr_common.allowSystemTableMods &&
!u_sess->attr.attr_common.IsInplaceUpgrade && IsSystemRelation(pstate->p_target_relation) &&
(strcmp(RelationGetRelationName(pstate->p_target_relation), "pg_authid") == 0 ||
strcmp(RelationGetRelationName(pstate->p_target_relation), "gs_global_config") == 0)) {
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: \"%s\" is a system catalog",
RelationGetRelationName(pstate->p_target_relation))));
}
if (IS_FOREIGNTABLE(pstate->p_target_relation)||IS_STREAM_TABLE(pstate->p_target_relation)) {
/*
* In the security mode, the useft privilege of a user must be
* checked before the user inserts into a foreign table.
*/
if (isSecurityMode && !have_useft_privilege()) {
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied to insert into foreign table in security mode")));
}
}
/*
* Override addRangeTableEntry's default ACL_SELECT permissions check, and
* instead mark target table as requiring exactly the specified
* permissions.
*
* If we find an explicit reference to the rel later during parse
* analysis, we will add the ACL_SELECT bit back again; see
* markVarForSelectPriv and its callers.
*/
rte->requiredPerms = requiredPerms;
/*
* If UPDATE/DELETE, add table to joinlist and namespaces.
*/
if (alsoSource) {
addRTEtoQuery(pstate, rte, true, true, true);
}
return rtindex;
}
/*
* Simplify InhOption (yes/no/default) into boolean yes/no.
*
* The reason we do things this way is that we don't want to examine the
* SQL_inheritance option flag until parse_analyze() is run. Otherwise,
* we'd do the wrong thing with query strings that intermix SET commands
* with queries.
*/
bool interpretInhOption(InhOption inhOpt)
{
switch (inhOpt) {
case INH_NO:
return false;
case INH_YES:
return true;
case INH_DEFAULT:
return u_sess->attr.attr_sql.SQL_inheritance;
default:
break;
}
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("bogus InhOption value: %d", inhOpt)));
return false; /* keep compiler quiet */
}
/*
* Given a relation-options list (of DefElems), return true iff the specified
* table/result set should be created with OIDs. This needs to be done after
* parsing the query string because the return value can depend upon the
* default_with_oids GUC var.
*/
bool interpretOidsOption(List* defList)
{
ListCell* cell = NULL;
/* Scan list to see if OIDS was included */
foreach (cell, defList) {
DefElem* def = (DefElem*)lfirst(cell);
if (def->defnamespace == NULL && pg_strcasecmp(def->defname, "oids") == 0) {
return defGetBoolean(def);
}
}
/* OIDS option was not specified, so use default. */
return false;
}
/*
* Extract all not-in-common columns from column lists of a source table
*/
static void extractRemainingColumns(
List* common_colnames, List* src_colnames, List* src_colvars, List** res_colnames, List** res_colvars)
{
List* new_colnames = NIL;
List* new_colvars = NIL;
ListCell *lnames = NULL;
ListCell *lvars = NULL;
AssertEreport(list_length(src_colnames) == list_length(src_colvars), MOD_OPT, "list length inconsistant");
forboth(lnames, src_colnames, lvars, src_colvars)
{
char* colname = strVal(lfirst(lnames));
bool match = false;
ListCell* cnames = NULL;
foreach (cnames, common_colnames) {
char* ccolname = strVal(lfirst(cnames));
if (strcmp(colname, ccolname) == 0) {
match = true;
break;
}
}
if (!match) {
new_colnames = lappend(new_colnames, lfirst(lnames));
new_colvars = lappend(new_colvars, lfirst(lvars));
}
}
*res_colnames = new_colnames;
*res_colvars = new_colvars;
}
/* transformJoinUsingClause
* Build a complete ON clause from a partially-transformed USING list.
* We are given lists of nodes representing left and right match columns.
* Result is a transformed qualification expression.
*/
static Node* transformJoinUsingClause(
ParseState* pstate, RangeTblEntry* leftRTE, RangeTblEntry* rightRTE, List* leftVars, List* rightVars)
{
Node* result = NULL;
ListCell* lvars = NULL;
ListCell* rvars = NULL;
/*
* We cheat a little bit here by building an untransformed operator tree
* whose leaves are the already-transformed Vars. This is OK because
* transformExpr() won't complain about already-transformed subnodes.
* However, this does mean that we have to mark the columns as requiring
* SELECT privilege for ourselves; transformExpr() won't do it.
*/
forboth(lvars, leftVars, rvars, rightVars)
{
Var* lvar = (Var*)lfirst(lvars);
Var* rvar = (Var*)lfirst(rvars);
A_Expr* e = NULL;
/* Require read access to the join variables */
markVarForSelectPriv(pstate, lvar, leftRTE);
markVarForSelectPriv(pstate, rvar, rightRTE);
/* Now create the lvar = rvar join condition */
e = makeSimpleA_Expr(AEXPR_OP, "=", (Node*)copyObject(lvar), (Node*)copyObject(rvar), -1);
/* And combine into an AND clause, if multiple join columns */
if (result == NULL)
result = (Node*)e;
else {
A_Expr* a = NULL;
a = makeA_Expr(AEXPR_AND, NIL, result, (Node*)e, -1);
result = (Node*)a;
}
}
/*
* Since the references are already Vars, and are certainly from the input
* relations, we don't have to go through the same pushups that
* transformJoinOnClause() does. Just invoke transformExpr() to fix up
* the operators, and we're done.
*/
result = transformExpr(pstate, result);
result = coerce_to_boolean(pstate, result, "JOIN/USING");
return result;
}
/* transformJoinOnClause
* Transform the qual conditions for JOIN/ON.
* Result is a transformed qualification expression.
*/
Node* transformJoinOnClause(ParseState* pstate, JoinExpr* j, RangeTblEntry* l_rte, RangeTblEntry* r_rte,
List* relnamespace)
{
Node* result = NULL;
List* save_relnamespace = NIL;
List* save_varnamespace = NIL;
/*
* This is a tad tricky, for two reasons. First, the namespace that the
* join expression should see is just the two subtrees of the JOIN plus
* any outer references from upper pstate levels. So, temporarily set
* this pstate's namespace accordingly. (We need not check for refname
* conflicts, because transformFromClauseItem() already did.) NOTE: this
* code is OK only because the ON clause can't legally alter the namespace
* by causing implicit relation refs to be added.
*/
save_relnamespace = pstate->p_relnamespace;
save_varnamespace = pstate->p_varnamespace;
setNamespaceLateralState(relnamespace, false, true);
pstate->p_relnamespace = relnamespace;
pstate->p_varnamespace = list_make2(makeNamespaceItem(l_rte, false, true),
makeNamespaceItem(r_rte, false, true));
result = transformWhereClause(pstate, j->quals, "JOIN/ON");
pstate->p_relnamespace = save_relnamespace;
pstate->p_varnamespace = save_varnamespace;
return result;
}
/*
* transformTableEntry --- transform a RangeVar (simple relation reference)
*/
static RangeTblEntry* transformTableEntry(ParseState* pstate, RangeVar* r, bool isFirstNode, bool isCreateView)
{
RangeTblEntry* rte = NULL;
/*
* mark this entry to indicate it comes from the FROM clause. In SQL, the
* target list can only refer to range variables specified in the from
* clause but we follow the more powerful POSTQUEL semantics and
* automatically generate the range variable if not specified. However
* there are times we need to know whether the entries are legitimate.
* Here, option isSupportSynonym is true, means that we one synonym object is this entry.
*/
rte = addRangeTableEntry(pstate, r, r->alias, interpretInhOption(r->inhOpt), true, isFirstNode, isCreateView, true);
return rte;
}
/*
* transformCTEReference --- transform a RangeVar that references a common
* table expression (ie, a sub-SELECT defined in a WITH clause)
*/
static RangeTblEntry* transformCTEReference(ParseState* pstate, RangeVar* r, CommonTableExpr* cte, Index levelsup)
{
RangeTblEntry* rte = NULL;
if (r->ispartition) {
ereport(
ERROR, (errcode(ERRCODE_UNDEFINED_TABLE), errmsg("relation \"%s\" is not partitioned table", r->relname)));
}
rte = addRangeTableEntryForCTE(pstate, cte, levelsup, r, true);
return rte;
}
/*
* transformRangeSubselect --- transform a sub-SELECT appearing in FROM
*/
static RangeTblEntry* transformRangeSubselect(ParseState* pstate, RangeSubselect* r)
{
Query* query = NULL;
RangeTblEntry* rte = NULL;
/*
* We require user to supply an alias for a subselect, per SQL92. To relax
* this, we'd have to be prepared to gin up a unique alias for an
* unlabeled subselect. (This is just elog, not ereport, because the
* grammar should have enforced it already.)
*/
if (r->alias == NULL) {
ereport(ERROR, (errcode(ERRCODE_UNEXPECTED_NULL_VALUE), errmsg("subquery in FROM must have an alias")));
}
/*
* If the subselect is LATERAL, make lateral_only names of this level
* visible to it. (LATERAL can't nest within a single pstate level, so we
* don't need save/restore logic here.)
*/
Assert(!pstate->p_lateral_active);
pstate->p_lateral_active = r->lateral;
/*
* Analyze and transform the subquery.
*/
query = parse_sub_analyze(r->subquery, pstate, NULL, isLockedRefname(pstate, r->alias->aliasname), true);
pstate->p_lateral_active = false;
/*
* Check that we got something reasonable. Many of these conditions are
* impossible given restrictions of the grammar, but check 'em anyway.
*/
if (!IsA(query, Query) || query->commandType != CMD_SELECT || query->utilityStmt != NULL) {
ereport(ERROR,
(errcode(ERRCODE_UNEXPECTED_NODE_STATE), errmsg("unexpected non-SELECT command in subquery in FROM")));
}
/*
* OK, build an RTE for the subquery.
*/
rte = addRangeTableEntryForSubquery(pstate, query, r->alias, r->lateral, true);
return rte;
}
/*
* transformRangeFunction --- transform a function call appearing in FROM
*/
static RangeTblEntry* transformRangeFunction(ParseState* pstate, RangeFunction* r)
{
Node* funcexpr = NULL;
char* funcname = NULL;
RangeTblEntry* rte = NULL;
/*
* Get function name for possible use as alias. We use the same
* transformation rules as for a SELECT output expression. For a FuncCall
* node, the result will be the function name, but it is possible for the
* grammar to hand back other node types.
*/
funcname = FigureColname(r->funccallnode);
/*
* If the function is LATERAL, make lateral_only names of this level
* visible to it. (LATERAL can't nest within a single pstate level, so we
* don't need save/restore logic here.)
*/
Assert(!pstate->p_lateral_active);
pstate->p_lateral_active = r->lateral;
/*
* Transform the raw expression.
*/
funcexpr = transformExpr(pstate, r->funccallnode);
pstate->p_lateral_active = false;
/*
* We must assign collations now so that we can fill funccolcollations.
*/
assign_expr_collations(pstate, funcexpr);
/*
* Disallow aggregate functions in the expression. (No reason to postpone
* this check until parseCheckAggregates.)
*/
if (pstate->p_hasAggs && checkExprHasAggs(funcexpr)) {
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
errmsg("cannot use aggregate function in function expression in FROM"),
parser_errposition(pstate, locate_agg_of_level(funcexpr, 0))));
}
if (pstate->p_hasWindowFuncs && checkExprHasWindowFuncs(funcexpr)) {
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot use window function in function expression in FROM"),
parser_errposition(pstate, locate_windowfunc(funcexpr))));
}
/*
* OK, build an RTE for the function.
*/
rte = addRangeTableEntryForFunction(pstate, funcname, funcexpr, r, r->lateral, true);
/*
* If a coldeflist was supplied, ensure it defines a legal set of names
* (no duplicates) and datatypes (no pseudo-types, for instance).
* addRangeTableEntryForFunction looked up the type names but didn't check
* them further than that.
*/
if (r->coldeflist) {
TupleDesc tupdesc;
tupdesc =
BuildDescFromLists(rte->eref->colnames, rte->funccoltypes, rte->funccoltypmods, rte->funccolcollations);
CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE, false);
}
return rte;
}
/*
* Description: Transform a TABLESAMPLE clause
* Caller has already transformed rts->relation, we just have to validate
* the remaining fields and create a TableSampleClause node.
*
* Parameters:
* @in pstate: state information used during parse analysis.
* @in rts: TABLESAMPLE appearing in a raw FROM clause.
*
* Return: TABLESAMPLE appearing in a transformed FROM clause.
*/
static TableSampleClause* transformRangeTableSample(ParseState* pstate, RangeTableSample* rts)
{
TableSampleClause* tablesample = NULL;
List* fargs = NIL;
ListCell* larg = NULL;
/* Method only one, system or bernoulli. */
AssertEreport(list_length(rts->method) == 1, MOD_OPT, "Method shoud only one, system or bernoulli");
char* methodName = strVal(linitial(rts->method));
tablesample = makeNode(TableSampleClause);
if (strncmp(methodName, "system", sizeof("system")) == 0) {
tablesample->sampleType = SYSTEM_SAMPLE;
} else if (strncmp(methodName, "bernoulli", sizeof("bernoulli")) == 0) {
tablesample->sampleType = BERNOULLI_SAMPLE;
} else if (strncmp(methodName, "hybrid", sizeof("hybrid")) == 0) {
tablesample->sampleType = HYBRID_SAMPLE;
} else {
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("Invalid tablesample method %s", methodName),
parser_errposition(pstate, rts->location)));
}
/* check user provided the expected number of arguments */
if ((HYBRID_SAMPLE == tablesample->sampleType && list_length(rts->args) != SAMPLEARGSNUM) ||
(HYBRID_SAMPLE != tablesample->sampleType && list_length(rts->args) != SAMPLEARGSNUM - 1)) {
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("tablesample method %s requires %d argument, not %d",
methodName,
(HYBRID_SAMPLE == tablesample->sampleType ? SAMPLEARGSNUM : SAMPLEARGSNUM - 1),
list_length(rts->args)),
parser_errposition(pstate, rts->location)));
}
/*
* Transform the arguments, typecasting them as needed. Note we must also
* assign collations now, because assign_query_collations() doesn't
* examine any substructure of RTEs.
*/
fargs = NIL;
foreach (larg, rts->args) {
Node* arg = (Node*)lfirst(larg);
arg = transformExpr(pstate, arg);
arg = coerce_to_specific_type(pstate, arg, FLOAT4OID, "TABLESAMPLE");
assign_expr_collations(pstate, arg);
fargs = lappend(fargs, arg);
}
tablesample->args = fargs;
/* Process REPEATABLE (seed) */
if (rts->repeatable != NULL) {
Node* arg = NULL;
arg = transformExpr(pstate, rts->repeatable);
arg = coerce_to_specific_type(pstate, arg, FLOAT8OID, "REPEATABLE");
assign_expr_collations(pstate, arg);
tablesample->repeatable = (Expr*)arg;
} else {
tablesample->repeatable = NULL;
}
return tablesample;
}
/*
* transformFromClauseItem -
* Transform a FROM-clause item, adding any required entries to the
* range table list being built in the ParseState, and return the
* transformed item ready to include in the joinlist and namespaces.
* This routine can recurse to handle SQL92 JOIN expressions.
*
* The function return value is the node to add to the jointree (a
* RangeTblRef or JoinExpr). Additional output parameters are:
*
* *top_rte: receives the RTE corresponding to the jointree item.
* (We could extract this from the function return node, but it saves cycles
* to pass it back separately.)
*
* *top_rti: receives the rangetable index of top_rte. (Ditto.)
*
* *right_rte: receives the RTE corresponding to the right side of the
* jointree. Only MERGE really needs to know about this and only MERGE passes a
* non-NULL pointer.
*
* *right_rti: receives the rangetable index of the right_rte.
*
* *relnamespace: receives a List of the RTEs exposed as relation names
* by this item.
*
* *containedRels: receives a bitmap set of the rangetable indexes
* of all the base and join relations represented in this jointree item.
* This is needed for checking JOIN/ON conditions in higher levels.
*
* We do not need to pass back an explicit varnamespace value, because
* in all cases the varnamespace contribution is exactly top_rte.
*/
Node* transformFromClauseItem(ParseState* pstate, Node* n, RangeTblEntry** top_rte, int* top_rti,
RangeTblEntry** right_rte, int* right_rti, List** relnamespace, bool isFirstNode,
bool isCreateView, bool isMergeInto)
{
if (IsA(n, RangeVar)) {
/* Plain relation reference, or perhaps a CTE reference */
RangeVar* rv = (RangeVar*)n;
RangeTblRef* rtr = NULL;
RangeTblEntry* rte = NULL;
/* if it is an unqualified name, it might be a CTE reference */
if (!rv->schemaname) {
CommonTableExpr* cte = NULL;
Index levelsup;
cte = scanNameSpaceForCTE(pstate, rv->relname, &levelsup);
if (cte != NULL) {
rte = transformCTEReference(pstate, rv, cte, levelsup);
}
}
/* if not found as a CTE, must be a table reference */
if (rte == NULL) {
rte = transformTableEntry(pstate, rv, isFirstNode, isCreateView);
}
rtr = transformItem(pstate, rte, top_rte, top_rti, relnamespace);
return (Node*)rtr;
} else if (IsA(n, RangeSubselect)) {
/* sub-SELECT is like a plain relation */
RangeTblRef* rtr = NULL;
RangeTblEntry* rte = NULL;
rte = transformRangeSubselect(pstate, (RangeSubselect*)n);
rtr = transformItem(pstate, rte, top_rte, top_rti, relnamespace);
return (Node*)rtr;
} else if (IsA(n, RangeFunction)) {
/* function is like a plain relation */
RangeTblRef* rtr = NULL;
RangeTblEntry* rte = NULL;
rte = transformRangeFunction(pstate, (RangeFunction*)n);
rtr = transformItem(pstate, rte, top_rte, top_rti, relnamespace);
return (Node*)rtr;
} else if (IsA(n, RangeTableSample)) {
/* TABLESAMPLE clause (wrapping some other valid FROM NODE) */
RangeTableSample* rts = (RangeTableSample*)n;
Node* rel = NULL;
RangeTblRef* rtr = NULL;
RangeTblEntry* rte = NULL;
/* Recursively transform the contained relation. */
rel = transformFromClauseItem(pstate, rts->relation, top_rte, top_rti, NULL, NULL, relnamespace);
if (unlikely(rel == NULL)) {
ereport(
ERROR, (errmodule(MOD_OPT), errcode(ERRCODE_UNEXPECTED_NULL_VALUE), errmsg("rel should not be NULL")));
}
/* Currently, grammar could only return a RangeVar as contained rel */
Assert(IsA(rel, RangeTblRef));
rtr = (RangeTblRef*)rel;
rte = rt_fetch(rtr->rtindex, pstate->p_rtable);
/* We only support this on plain relations */
if (rte->relkind != RELKIND_RELATION) {
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("TABLESAMPLE clause can only be applied to tables."),
parser_errposition(pstate, exprLocation(rts->relation))));
}
if (REL_COL_ORIENTED != rte->orientation && REL_ROW_ORIENTED != rte->orientation) {
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
(errmsg("TABLESAMPLE clause only support relation of oriented-row and oriented-column."))));
}
/* Transform TABLESAMPLE details and attach to the RTE */
rte->tablesample = transformRangeTableSample(pstate, rts);
return (Node*)rtr;
} else if (IsA(n, JoinExpr)) {
/* A newfangled join expression */
JoinExpr* j = (JoinExpr*)n;
RangeTblEntry* l_rte = NULL;
RangeTblEntry* r_rte = NULL;
int l_rtindex;
int r_rtindex;
List* l_relnamespace = NIL;
List* r_relnamespace = NIL;
List* my_relnamespace = NIL;
List* l_colnames = NIL;
List* r_colnames = NIL;
List* res_colnames = NIL;
List* l_colvars = NIL;
List* r_colvars = NIL;
List* res_colvars = NIL;
bool lateral_ok = false;
int sv_relnamespace_length, sv_varnamespace_length;
RangeTblEntry* rte = NULL;
int k;
/*
* Recursively process the left and right subtrees
* For merge into clause, left arg is alse the target relation, which has been
* added to the range table. Here, we only build RangeTblRef.
*/
if (isMergeInto == false) {
j->larg = transformFromClauseItem(
pstate, j->larg, &l_rte, &l_rtindex, NULL, NULL, &l_relnamespace);
} else {
RangeTblRef* rtr = makeNode(RangeTblRef);
rtr->rtindex = list_length(pstate->p_rtable);
j->larg = (Node*)rtr;
l_rte = pstate->p_target_rangetblentry;
l_rtindex = rtr->rtindex;
l_relnamespace = list_make1(makeNamespaceItem(l_rte, false, true));
}
/*
* Make the left-side RTEs available for LATERAL access within the
* right side, by temporarily adding them to the pstate's namespace
* lists. Per SQL:2008, if the join type is not INNER or LEFT then
* the left-side names must still be exposed, but it's an error to
* reference them. (Stupid design, but that's what it says.) Hence,
* we always push them into the namespaces, but mark them as not
* lateral_ok if the jointype is wrong.
*
* NB: this coding relies on the fact that list_concat is not
* destructive to its second argument.
*/
lateral_ok = (j->jointype == JOIN_INNER || j->jointype == JOIN_LEFT);
setNamespaceLateralState(l_relnamespace, true, lateral_ok);
sv_relnamespace_length = list_length(pstate->p_relnamespace);
pstate->p_relnamespace = list_concat(pstate->p_relnamespace,
l_relnamespace);
sv_varnamespace_length = list_length(pstate->p_varnamespace);
pstate->p_varnamespace = lappend(pstate->p_varnamespace,
makeNamespaceItem(l_rte, true, lateral_ok));
/* And now we can process the RHS */
j->rarg = transformFromClauseItem(pstate, j->rarg, &r_rte, &r_rtindex, NULL, NULL, &r_relnamespace);
/* Remove the left-side RTEs from the namespace lists again */
pstate->p_relnamespace = list_truncate(pstate->p_relnamespace,sv_relnamespace_length);
pstate->p_varnamespace = list_truncate(pstate->p_varnamespace, sv_varnamespace_length);
/*
* Check for conflicting refnames in left and right subtrees. Must do
* this because higher levels will assume I hand back a self-
* consistent namespace subtree.
*/
checkNameSpaceConflicts(pstate, l_relnamespace, r_relnamespace);
/*
* Generate combined relation membership info for possible use by
* transformJoinOnClause below.
*/
my_relnamespace = list_concat(l_relnamespace, r_relnamespace);
/*
* Extract column name and var lists from both subtrees
*
* Note: expandRTE returns new lists, safe for me to modify
*/
expandRTE(l_rte, l_rtindex, 0, -1, false, &l_colnames, &l_colvars);
expandRTE(r_rte, r_rtindex, 0, -1, false, &r_colnames, &r_colvars);
if (right_rte != NULL) {
*right_rte = r_rte;
}
if (right_rti != NULL) {
*right_rti = r_rtindex;
}
/*
* Natural join does not explicitly specify columns; must generate
* columns to join. Need to run through the list of columns from each
* table or join result and match up the column names. Use the first
* table, and check every column in the second table for a match.
* (We'll check that the matches were unique later on.) The result of
* this step is a list of column names just like an explicitly-written
* USING list.
*/
if (j->isNatural) {
List* rlist = NIL;
ListCell* lx = NULL;
ListCell* rx = NULL;
/* shouldn't have USING() too */
Assert(j->usingClause == NIL);
foreach (lx, l_colnames) {
char* l_colname = strVal(lfirst(lx));
Value* m_name = NULL;
foreach (rx, r_colnames) {
char* r_colname = strVal(lfirst(rx));
if (strcmp(l_colname, r_colname) == 0) {
m_name = makeString(l_colname);
break;
}
}
/* matched a right column? then keep as join column... */
if (m_name != NULL) {
rlist = lappend(rlist, m_name);
}
}
j->usingClause = rlist;
}
/*
* Now transform the join qualifications, if any.
*/
res_colnames = NIL;
res_colvars = NIL;
if (j->usingClause) {
/*
* JOIN/USING (or NATURAL JOIN, as transformed above). Transform
* the list into an explicit ON-condition, and generate a list of
* merged result columns.
*/
List* ucols = j->usingClause;
List* l_usingvars = NIL;
List* r_usingvars = NIL;
ListCell* ucol = NULL;
/* shouldn't have ON() too */
Assert(j->quals == NULL);
foreach (ucol, ucols) {
char* u_colname = strVal(lfirst(ucol));
ListCell* col = NULL;
int ndx;
int l_index = -1;
int r_index = -1;
Var *l_colvar = NULL;
Var *r_colvar = NULL;
/* Check for USING(foo,foo) */
foreach (col, res_colnames) {
char* res_colname = strVal(lfirst(col));
if (strcmp(res_colname, u_colname) == 0) {
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_COLUMN),
errmsg("column name \"%s\" appears more than once in USING clause", u_colname)));
}
}
/* Find it in left input */
ndx = 0;
foreach (col, l_colnames) {
char* l_colname = strVal(lfirst(col));
if (strcmp(l_colname, u_colname) == 0) {
if (l_index >= 0)
ereport(ERROR,
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
errmsg(
"common column name \"%s\" appears more than once in left table", u_colname)));
l_index = ndx;
}
ndx++;
}
if (l_index < 0) {
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("column \"%s\" specified in USING clause does not exist in left table", u_colname)));
}
/* Find it in right input */
ndx = 0;
foreach (col, r_colnames) {
char* r_colname = strVal(lfirst(col));
if (strcmp(r_colname, u_colname) == 0) {
if (r_index >= 0) {
ereport(ERROR,
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
errmsg(
"common column name \"%s\" appears more than once in right table", u_colname)));
}
r_index = ndx;
}
ndx++;
}
if (r_index < 0) {
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg(
"column \"%s\" specified in USING clause does not exist in right table", u_colname)));
}
l_colvar = (Var*)list_nth(l_colvars, l_index);
l_usingvars = lappend(l_usingvars, l_colvar);
r_colvar = (Var*)list_nth(r_colvars, r_index);
r_usingvars = lappend(r_usingvars, r_colvar);
res_colnames = lappend(res_colnames, lfirst(ucol));
res_colvars = lappend(res_colvars, buildMergedJoinVar(pstate, j->jointype, l_colvar, r_colvar));
}
j->quals = transformJoinUsingClause(pstate, l_rte, r_rte, l_usingvars, r_usingvars);
} else if (j->quals) {
/* User-written ON-condition; transform it */
j->quals = transformJoinOnClause(pstate, j, l_rte, r_rte, my_relnamespace);
} else {
/* CROSS JOIN: no quals */
}
/* Add remaining columns from each side to the output columns */
extractRemainingColumns(res_colnames, l_colnames, l_colvars, &l_colnames, &l_colvars);
extractRemainingColumns(res_colnames, r_colnames, r_colvars, &r_colnames, &r_colvars);
res_colnames = list_concat(res_colnames, l_colnames);
res_colvars = list_concat(res_colvars, l_colvars);
res_colnames = list_concat(res_colnames, r_colnames);
res_colvars = list_concat(res_colvars, r_colvars);
/*
* Check alias (AS clause), if any.
*/
if (j->alias) {
if (j->alias->colnames != NIL) {
if (list_length(j->alias->colnames) > list_length(res_colnames))
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("column alias list for \"%s\" has too many entries", j->alias->aliasname)));
}
}
/*
* Now build an RTE for the result of the join
*/
rte = addRangeTableEntryForJoin(pstate, res_colnames, j->jointype, res_colvars, j->alias, true);
/* assume new rte is at end */
j->rtindex = list_length(pstate->p_rtable);
Assert(rte == rt_fetch(j->rtindex, pstate->p_rtable));
*top_rte = rte;
*top_rti = j->rtindex;
/* make a matching link to the JoinExpr for later use */
for (k = list_length(pstate->p_joinexprs) + 1; k < j->rtindex; k++) {
pstate->p_joinexprs = lappend(pstate->p_joinexprs, NULL);
}
pstate->p_joinexprs = lappend(pstate->p_joinexprs, j);
Assert(list_length(pstate->p_joinexprs) == j->rtindex);
/*
* Prepare returned namespace list. If the JOIN has an alias then it
* hides the contained RTEs as far as the relnamespace goes;
* otherwise, put the contained RTEs and *not* the JOIN into
* relnamespace.
*/
if (j->alias) {
*relnamespace = list_make1(makeNamespaceItem(rte, false, true));
} else
*relnamespace = my_relnamespace;
return (Node*)j;
} else
ereport(
ERROR, (errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized node type: %d", (int)nodeTag(n))));
return NULL; /* can't get here, keep compiler quiet */
}
/*
* makeNamespaceItem -
* Convenience subroutine to construct a ParseNamespaceItem.
*/
ParseNamespaceItem *
makeNamespaceItem(RangeTblEntry *rte, bool lateral_only, bool lateral_ok)
{
ParseNamespaceItem *nsitem;
nsitem = (ParseNamespaceItem *) palloc(sizeof(ParseNamespaceItem));
nsitem->p_rte = rte;
nsitem->p_lateral_only = lateral_only;
nsitem->p_lateral_ok = lateral_ok;
return nsitem;
}
/*
* setNamespaceLateralState -
* Convenience subroutine to update LATERAL flags in a namespace list.
*/
static void
setNamespaceLateralState(List *l_namespace, bool lateral_only, bool lateral_ok)
{
ListCell *lc = NULL;
foreach(lc, l_namespace)
{
ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc);
nsitem->p_lateral_only = lateral_only;
nsitem->p_lateral_ok = lateral_ok;
}
}
/*
* buildMergedJoinVar -
* generate a suitable replacement expression for a merged join column
*/
static Node* buildMergedJoinVar(ParseState* pstate, JoinType jointype, Var* l_colvar, Var* r_colvar)
{
Oid outcoltype;
int32 outcoltypmod;
Node* l_node = NULL;
Node* r_node = NULL;
Node* res_node = NULL;
/*
* Choose output type if input types are dissimilar.
*/
outcoltype = l_colvar->vartype;
outcoltypmod = l_colvar->vartypmod;
if (outcoltype != r_colvar->vartype) {
outcoltype = select_common_type(pstate, list_make2(l_colvar, r_colvar), "JOIN/USING", NULL);
outcoltypmod = -1; /* ie, unknown */
} else if (outcoltypmod != r_colvar->vartypmod) {
/* same type, but not same typmod */
outcoltypmod = -1; /* ie, unknown */
}
/*
* Insert coercion functions if needed. Note that a difference in typmod
* can only happen if input has typmod but outcoltypmod is -1. In that
* case we insert a RelabelType to clearly mark that result's typmod is
* not same as input. We never need coerce_type_typmod.
*/
if (l_colvar->vartype != outcoltype) {
l_node = coerce_type(pstate,
(Node*)l_colvar,
l_colvar->vartype,
outcoltype,
outcoltypmod,
COERCION_IMPLICIT,
COERCE_IMPLICIT_CAST,
-1);
} else if (l_colvar->vartypmod != outcoltypmod) {
l_node = (Node*)makeRelabelType((Expr*)l_colvar,
outcoltype,
outcoltypmod,
InvalidOid, /* fixed below */
COERCE_IMPLICIT_CAST);
} else {
l_node = (Node*)l_colvar;
}
if (r_colvar->vartype != outcoltype) {
r_node = coerce_type(pstate,
(Node*)r_colvar,
r_colvar->vartype,
outcoltype,
outcoltypmod,
COERCION_IMPLICIT,
COERCE_IMPLICIT_CAST,
-1);
} else if (r_colvar->vartypmod != outcoltypmod) {
r_node = (Node*)makeRelabelType((Expr*)r_colvar,
outcoltype,
outcoltypmod,
InvalidOid, /* fixed below */
COERCE_IMPLICIT_CAST);
} else {
r_node = (Node*)r_colvar;
}
/*
* Choose what to emit
*/
switch (jointype) {
case JOIN_INNER:
/*
* We can use either var; prefer non-coerced one if available.
*/
if (IsA(l_node, Var)) {
res_node = l_node;
} else if (IsA(r_node, Var)) {
res_node = r_node;
} else {
res_node = l_node;
}
break;
case JOIN_LEFT:
case JOIN_LEFT_ANTI_FULL:
/* Always use left var */
res_node = l_node;
break;
case JOIN_RIGHT:
case JOIN_RIGHT_ANTI_FULL:
/* Always use right var */
res_node = r_node;
break;
case JOIN_FULL: {
/*
* Here we must build a COALESCE expression to ensure that the
* join output is non-null if either input is.
*/
CoalesceExpr* c = makeNode(CoalesceExpr);
c->coalescetype = outcoltype;
/* coalescecollid will get set below */
c->args = list_make2(l_node, r_node);
c->location = -1;
res_node = (Node*)c;
break;
}
default:
ereport(
ERROR, (errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized join type: %d", (int)jointype)));
res_node = NULL; /* keep compiler quiet */
break;
}
/*
* Apply assign_expr_collations to fix up the collation info in the
* coercion and CoalesceExpr nodes, if we made any. This must be done now
* so that the join node's alias vars show correct collation info.
*/
assign_expr_collations(pstate, res_node);
return res_node;
}
/*
* transformWhereClause -
* Transform the qualification and make sure it is of type boolean.
* Used for WHERE and allied clauses.
*
* constructName does not affect the semantics, but is used in error messages
*/
Node* transformWhereClause(ParseState* pstate, Node* clause, const char* constructName)
{
Node* qual = NULL;
if (clause == NULL) {
return NULL;
}
qual = transformExpr(pstate, clause);
qual = coerce_to_boolean(pstate, qual, constructName);
return qual;
}
/*
* transformLimitClause -
* Transform the expression and make sure it is of type bigint.
* Used for LIMIT and allied clauses.
*
* Note: as of Postgres 8.2, LIMIT expressions are expected to yield int8,
* rather than int4 as before.
*
* constructName does not affect the semantics, but is used in error messages
*/
Node* transformLimitClause(ParseState* pstate, Node* clause, const char* constructName)
{
Node* qual = NULL;
if (clause == NULL) {
return NULL;
}
qual = transformExpr(pstate, clause);
qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName);
/* LIMIT can't refer to any vars or aggregates of the current query */
checkExprIsVarFree(pstate, qual, constructName);
return qual;
}
/*
* checkExprIsVarFree
* Check that given expr has no Vars of the current query level
* (and no aggregates or window functions, either).
*
* This is used to check expressions that have to have a consistent value
* across all rows of the query, such as a LIMIT. Arguably it should reject
* volatile functions, too, but we don't do that --- whatever value the
* function gives on first execution is what you get.
*
* constructName does not affect the semantics, but is used in error messages
*/
static void checkExprIsVarFree(ParseState* pstate, Node* n, const char* constructName)
{
if (contain_vars_of_level(n, 0)) {
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
/* translator: %s is name of a SQL construct, eg LIMIT */
errmsg("argument of %s must not contain variables", constructName),
parser_errposition(pstate, locate_var_of_level(n, 0))));
}
if (pstate->p_hasAggs && checkExprHasAggs(n)) {
ereport(ERROR,
(errcode(ERRCODE_GROUPING_ERROR),
/* translator: %s is name of a SQL construct, eg LIMIT */
errmsg("argument of %s must not contain aggregate functions", constructName),
parser_errposition(pstate, locate_agg_of_level(n, 0))));
}
if (pstate->p_hasWindowFuncs && checkExprHasWindowFuncs(n)) {
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
/* translator: %s is name of a SQL construct, eg LIMIT */
errmsg("argument of %s must not contain window functions", constructName),
parser_errposition(pstate, locate_windowfunc(n))));
}
}
/*
* findTargetlistEntrySQL92 -
* Returns the targetlist entry matching the given (untransformed) node.
* If no matching entry exists, one is created and appended to the target
* list as a "resjunk" node.
*
* This function supports the old SQL92 ORDER BY interpretation, where the
* expression is an output column name or number. If we fail to find a
* match of that sort, we fall through to the SQL99 rules. For historical
* reasons, Postgres also allows this interpretation for GROUP BY, though
* the standard never did. However, for GROUP BY we prefer a SQL99 match.
* This function is *not* used for WINDOW definitions.
*
* node the ORDER BY, GROUP BY, or DISTINCT ON expression to be matched
* tlist the target list (passed by reference so we can append to it)
* clause identifies clause type being processed
*/
static TargetEntry* findTargetlistEntrySQL92(ParseState* pstate, Node* node, List** tlist, int clause)
{
ListCell* tl = NULL;
/* ----------
* Handle two special cases as mandated by the SQL92 spec:
*
* 1. Bare ColumnName (no qualifier or subscripts)
* For a bare identifier, we search for a matching column name
* in the existing target list. Multiple matches are an error
* unless they refer to identical values; for example,
* we allow SELECT a, a FROM table ORDER BY a
* but not SELECT a AS b, b FROM table ORDER BY b
* If no match is found, we fall through and treat the identifier
* as an expression.
* For GROUP BY, it is incorrect to match the grouping item against
* targetlist entries: according to SQL92, an identifier in GROUP BY
* is a reference to a column name exposed by FROM, not to a target
* list column. However, many implementations (including pre-7.0
* PostgreSQL) accept this anyway. So for GROUP BY, we look first
* to see if the identifier matches any FROM column name, and only
* try for a targetlist name if it doesn't. This ensures that we
* adhere to the spec in the case where the name could be both.
* DISTINCT ON isn't in the standard, so we can do what we like there;
* we choose to make it work like ORDER BY, on the rather flimsy
* grounds that ordinary DISTINCT works on targetlist entries.
*
* 2. IntegerConstant
* This means to use the n'th item in the existing target list.
* Note that it would make no sense to order/group/distinct by an
* actual constant, so this does not create a conflict with SQL99.
* GROUP BY column-number is not allowed by SQL92, but since
* the standard has no other behavior defined for this syntax,
* we may as well accept this common extension.
*
* Note that pre-existing resjunk targets must not be used in either case,
* since the user didn't write them in his SELECT list.
*
* If neither special case applies, fall through to treat the item as
* an expression per SQL99.
* ----------
*/
if (IsA(node, ColumnRef) && list_length(((ColumnRef*)node)->fields) == 1 &&
IsA(linitial(((ColumnRef*)node)->fields), String)) {
char* name = strVal(linitial(((ColumnRef*)node)->fields));
int location = ((ColumnRef*)node)->location;
if (clause == GROUP_CLAUSE) {
/*
* In GROUP BY, we must prefer a match against a FROM-clause
* column to one against the targetlist. Look to see if there is
* a matching column. If so, fall through to use SQL99 rules.
* NOTE: if name could refer ambiguously to more than one column
* name exposed by FROM, colNameToVar will ereport(ERROR). That's
* just what we want here.
*
* Small tweak for 7.4.3: ignore matches in upper query levels.
* This effectively changes the search order for bare names to (1)
* local FROM variables, (2) local targetlist aliases, (3) outer
* FROM variables, whereas before it was (1) (3) (2). SQL92 and
* SQL99 do not allow GROUPing BY an outer reference, so this
* breaks no cases that are legal per spec, and it seems a more
* self-consistent behavior.
*/
if (colNameToVar(pstate, name, true, location) != NULL)
name = NULL;
}
if (name != NULL) {
TargetEntry* target_result = NULL;
foreach (tl, *tlist) {
TargetEntry* tle = (TargetEntry*)lfirst(tl);
if (!tle->resjunk && strcmp(tle->resname, name) == 0) {
if (target_result != NULL) {
if (!equal(target_result->expr, tle->expr)) {
ereport(ERROR,
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
/* ------
translator: first %s is name of a SQL construct, eg ORDER BY */
errmsg("%s \"%s\" is ambiguous", clauseText[clause], name),
parser_errposition(pstate, location)));
}
} else {
target_result = tle; /* Stay in loop to check for ambiguity */
}
}
}
if (target_result != NULL)
return target_result; /* return the first match */
}
}
if (IsA(node, A_Const)) {
Value* val = &((A_Const*)node)->val;
int location = ((A_Const*)node)->location;
int targetlist_pos = 0;
int target_pos;
if (!IsA(val, Integer)) {
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
/* translator: %s is name of a SQL construct, eg ORDER BY */
errmsg("non-integer constant in %s", clauseText[clause]),
parser_errposition(pstate, location)));
}
target_pos = intVal(val);
foreach (tl, *tlist) {
TargetEntry* tle = (TargetEntry*)lfirst(tl);
if (!tle->resjunk) {
if (++targetlist_pos == target_pos) {
return tle; /* return the unique match */
}
}
}
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
/* translator: %s is name of a SQL construct, eg ORDER BY */
errmsg("%s position %d is not in select list", clauseText[clause], target_pos),
parser_errposition(pstate, location)));
}
/*
* Otherwise, we have an expression, so process it per SQL99 rules.
*/
return findTargetlistEntrySQL99(pstate, node, tlist);
}
/*
* findTargetlistEntrySQL99 -
* Returns the targetlist entry matching the given (untransformed) node.
* If no matching entry exists, one is created and appended to the target
* list as a "resjunk" node.
*
* This function supports the SQL99 interpretation, wherein the expression
* is just an ordinary expression referencing input column names.
*
* node the ORDER BY, GROUP BY, etc expression to be matched
* tlist the target list (passed by reference so we can append to it)
*/
static TargetEntry* findTargetlistEntrySQL99(ParseState* pstate, Node* node, List** tlist)
{
TargetEntry* target_result = NULL;
ListCell* tl = NULL;
Node* expr = NULL;
/*
* Convert the untransformed node to a transformed expression, and search
* for a match in the tlist. NOTE: it doesn't really matter whether there
* is more than one match. Also, we are willing to match an existing
* resjunk target here, though the SQL92 cases above must ignore resjunk
* targets.
*/
expr = transformExpr(pstate, node);
foreach (tl, *tlist) {
TargetEntry* tle = (TargetEntry*)lfirst(tl);
Node* texpr = NULL;
/*
* Ignore any implicit cast on the existing tlist expression.
*
* This essentially allows the ORDER/GROUP/etc item to adopt the same
* datatype previously selected for a textually-equivalent tlist item.
* There can't be any implicit cast at top level in an ordinary SELECT
* tlist at this stage, but the case does arise with ORDER BY in an
* aggregate function.
*/
texpr = strip_implicit_coercions((Node*)tle->expr);
if (equal(expr, texpr)) {
return tle;
}
}
/*
* If no matches, construct a new target entry which is appended to the
* end of the target list. This target is given resjunk = TRUE so that it
* will not be projected into the final tuple.
*/
target_result = transformTargetEntry(pstate, node, expr, NULL, true);
*tlist = lappend(*tlist, target_result);
return target_result;
}
/* -------------------------------------------------------------------------
* Flatten out parenthesized sublists in grouping lists, and some cases
* of nested grouping sets.
*
* Inside a grouping set (ROLLUP, CUBE, or GROUPING SETS), we expect the
* content to be nested no more than 2 deep: i.e. ROLLUP((a,b),(c,d)) is
* ok, but ROLLUP((a,(b,c)),d) is flattened to ((a,b,c),d), which we then
* (later) normalize to ((a,b,c),(d)).
*
* CUBE or ROLLUP can be nested inside GROUPING SETS (but not the reverse),
* and we leave that alone if we find it. But if we see GROUPING SETS inside
* GROUPING SETS, we can flatten and normalize as follows:
* GROUPING SETS (a, (b,c), GROUPING SETS ((c,d),(e)), (f,g))
* becomes
* GROUPING SETS ((a), (b,c), (c,d), (e), (f,g))
*
* This is per the spec's syntax transformations, but these are the only such
* transformations we do in parse analysis, so that queries retain the
* originally specified grouping set syntax for CUBE and ROLLUP as much as
* possible when deparsed. (Full expansion of the result into a list of
* grouping sets is left to the planner.)
*
* When we're done, the resulting list should contain only these possible
* elements:
* - an expression
* - a CUBE or ROLLUP with a list of expressions nested 2 deep
* - a GROUPING SET containing any of:
* - expression lists
* - empty grouping sets
* - CUBE or ROLLUP nodes with lists nested 2 deep
* The return is a new list, but doesn't deep-copy the old nodes except for
* GroupingSet nodes.
*
* As a side effect, flag whether the list has any GroupingSet nodes.
* -------------------------------------------------------------------------
*/
static Node* flatten_grouping_sets(Node* expr, bool toplevel, bool* hasGroupingSets)
{
/* just in case of pathological input */
check_stack_depth();
if (expr == (Node*)NIL)
return (Node*)NIL;
switch (expr->type) {
case T_RowExpr: {
RowExpr* r = (RowExpr*)expr;
if (r->row_format == COERCE_IMPLICIT_CAST)
return flatten_grouping_sets((Node*)r->args, false, NULL);
} break;
case T_GroupingSet: {
GroupingSet* gset = (GroupingSet*)expr;
ListCell* l2 = NULL;
List* result_set = NIL;
if (hasGroupingSets != NULL) {
*hasGroupingSets = true;
}
/*
* at the top level, we skip over all empty grouping sets; the
* caller can supply the canonical GROUP BY () if nothing is
* left.
*/
if (toplevel && gset->kind == GROUPING_SET_EMPTY)
return (Node*)NIL;
foreach (l2, gset->content) {
Node* n1 = (Node*)lfirst(l2);
Node* n2 = flatten_grouping_sets(n1, false, NULL);
if (IsA(n1, GroupingSet) && ((GroupingSet*)n1)->kind == GROUPING_SET_SETS) {
result_set = list_concat(result_set, (List*)n2);
} else {
result_set = lappend(result_set, n2);
}
}
/*
* At top level, keep the grouping set node; but if we're in a
* nested grouping set, then we need to concat the flattened
* result into the outer list if it's simply nested.
*/
if (toplevel || (gset->kind != GROUPING_SET_SETS)) {
return (Node*)makeGroupingSet(gset->kind, result_set, gset->location);
} else {
return (Node*)result_set;
}
}
case T_List: {
List* result = NIL;
ListCell* l = NULL;
foreach (l, (List*)expr) {
Node* n = flatten_grouping_sets((Node*)lfirst(l), toplevel, hasGroupingSets);
if (n != (Node*)NIL) {
if (IsA(n, List)) {
result = list_concat(result, (List*)n);
} else {
result = lappend(result, n);
}
}
}
return (Node*)result;
}
default:
break;
}
return expr;
}
/*
* Transform a single expression within a GROUP BY clause or grouping set.
*
* The expression is added to the targetlist if not already present, and to the
* flatresult list (which will become the groupClause) if not already present
* there. The sortClause is consulted for operator and sort order hints.
*
* Returns the ressortgroupref of the expression.
*
* flatresult reference to flat list of SortGroupClause nodes
* seen_local bitmapset of sortgrouprefs already seen at the local level
* pstate ParseState
* gexpr node to transform
* targetlist reference to TargetEntry list
* sortClause ORDER BY clause (SortGroupClause nodes)
* exprKind expression kind
* useSQL99 SQL99 rather than SQL92 syntax
* toplevel false if within any grouping set
*/
static Index transformGroupClauseExpr(List** flatresult, Bitmapset* seen_local, ParseState* pstate, Node* gexpr,
List** targetlist, List* sortClause, bool useSQL99, bool toplevel)
{
TargetEntry* tle = NULL;
bool found = false;
if (useSQL99) {
tle = findTargetlistEntrySQL99(pstate, gexpr, targetlist);
} else {
tle = findTargetlistEntrySQL92(pstate, gexpr, targetlist, GROUP_CLAUSE);
}
if (tle->ressortgroupref > 0) {
ListCell* sl = NULL;
/*
* Eliminate duplicates (GROUP BY x, x) but only at local level.
* (Duplicates in grouping sets can affect the number of returned
* rows, so can't be dropped indiscriminately.)
*
* Since we don't care about anything except the sortgroupref, we can
* use a bitmapset rather than scanning lists.
*/
if (bms_is_member(tle->ressortgroupref, seen_local)) {
return 0;
}
/*
* If we're already in the flat clause list, we don't need to consider
* adding ourselves again.
*/
found = targetIsInSortList(tle, InvalidOid, *flatresult);
if (found) {
return tle->ressortgroupref;
}
/*
* If the GROUP BY tlist entry also appears in ORDER BY, copy operator
* info from the (first) matching ORDER BY item. This means that if
* you write something like "GROUP BY foo ORDER BY foo USING <<<", the
* GROUP BY operation silently takes on the equality semantics implied
* by the ORDER BY. There are two reasons to do this: it improves the
* odds that we can implement both GROUP BY and ORDER BY with a single
* sort step, and it allows the user to choose the equality semantics
* used by GROUP BY, should she be working with a datatype that has
* more than one equality operator.
*
* If we're in a grouping set, though, we force our requested ordering
* to be NULLS LAST, because if we have any hope of using a sorted agg
* for the job, we're going to be tacking on generated NULL values
* after the corresponding groups. If the user demands nulls first,
* another sort step is going to be inevitable, but that's the
* planner's problem.
*/
foreach (sl, sortClause) {
SortGroupClause* sc = (SortGroupClause*)lfirst(sl);
if (sc->tleSortGroupRef == tle->ressortgroupref) {
SortGroupClause* grpc = (SortGroupClause*)copyObject(sc);
if (!toplevel) {
grpc->nulls_first = false;
}
*flatresult = lappend(*flatresult, grpc);
found = true;
break;
}
}
}
/*
* If no match in ORDER BY, just add it to the result using default
* sort/group semantics.
*/
if (!found) {
*flatresult = addTargetToGroupList(pstate, tle, *flatresult, *targetlist, exprLocation(gexpr), true);
}
/*
* _something_ must have assigned us a sortgroupref by now...
*/
return tle->ressortgroupref;
}
/*
* Transform a list of expressions within a GROUP BY clause or grouping set.
*
* The list of expressions belongs to a single clause within which duplicates
* can be safely eliminated.
*
* Returns an integer list of ressortgroupref values.
*
* flatresult reference to flat list of SortGroupClause nodes
* pstate ParseState
* list nodes to transform
* targetlist reference to TargetEntry list
* sortClause ORDER BY clause (SortGroupClause nodes)
* exprKind expression kind
* useSQL99 SQL99 rather than SQL92 syntax
* toplevel false if within any grouping set
*/
static List* transformGroupClauseList(List** flatresult, ParseState* pstate, List* list, List** targetlist,
List* sortClause, bool useSQL99, bool toplevel)
{
Bitmapset* seen_local = NULL;
List* result = NIL;
ListCell* gl = NULL;
foreach (gl, list) {
Node* gexpr = (Node*)lfirst(gl);
Index ref =
transformGroupClauseExpr(flatresult, seen_local, pstate, gexpr, targetlist, sortClause, useSQL99, toplevel);
if (ref > 0) {
seen_local = bms_add_member(seen_local, ref);
result = lappend_int(result, ref);
}
}
return result;
}
/*
* Transform a grouping set and (recursively) its content.
*
* The grouping set might be a GROUPING SETS node with other grouping sets
* inside it, but SETS within SETS have already been flattened out before
* reaching here.
*
* Returns the transformed node, which now contains SIMPLE nodes with lists
* of ressortgrouprefs rather than expressions.
*
* flatresult reference to flat list of SortGroupClause nodes
* pstate ParseState
* gset grouping set to transform
* targetlist reference to TargetEntry list
* sortClause ORDER BY clause (SortGroupClause nodes)
* exprKind expression kind
* useSQL99 SQL99 rather than SQL92 syntax
* toplevel false if within any grouping set
*/
static Node* transformGroupingSet(List** flatresult, ParseState* pstate, GroupingSet* gset, List** targetlist,
List* sortClause, bool useSQL99, bool toplevel)
{
ListCell* gl = NULL;
List* content = NIL;
AssertEreport(toplevel || gset->kind != GROUPING_SET_SETS, MOD_OPT, "");
foreach (gl, gset->content) {
Node* n = (Node*)lfirst(gl);
if (IsA(n, List)) {
List* l = transformGroupClauseList(flatresult, pstate, (List*)n, targetlist, sortClause, useSQL99, false);
content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE, l, exprLocation(n)));
} else if (IsA(n, GroupingSet)) {
GroupingSet* gset2 = (GroupingSet*)lfirst(gl);
content = lappend(
content, transformGroupingSet(flatresult, pstate, gset2, targetlist, sortClause, useSQL99, false));
} else {
Index ref = transformGroupClauseExpr(flatresult, NULL, pstate, n, targetlist, sortClause, useSQL99, false);
content = lappend(content, makeGroupingSet(GROUPING_SET_SIMPLE, list_make1_int(ref), exprLocation(n)));
}
}
/* Arbitrarily cap the size of CUBE, which has exponential growth */
if (gset->kind == GROUPING_SET_CUBE) {
if (list_length(content) > 12) {
ereport(ERROR,
(errcode(ERRCODE_TOO_MANY_COLUMNS),
errmsg("CUBE is limited to 12 elements"),
parser_errposition(pstate, gset->location)));
}
}
return (Node*)makeGroupingSet(gset->kind, content, gset->location);
}
/*
* transformGroupClause -
* transform a GROUP BY clause
*
* GROUP BY items will be added to the targetlist (as resjunk columns)
* if not already present, so the targetlist must be passed by reference.
*
* This is also used for window PARTITION BY clauses (which act almost the
* same, but are always interpreted per SQL99 rules).
*
* Grouping sets make this a lot more complex than it was. Our goal here is
* twofold: we make a flat list of SortGroupClause nodes referencing each
* distinct expression used for grouping, with those expressions added to the
* targetlist if needed. At the same time, we build the groupingSets tree,
* which stores only ressortgrouprefs as integer lists inside GroupingSet nodes
* (possibly nested, but limited in depth: a GROUPING_SET_SETS node can contain
* nested SIMPLE, CUBE or ROLLUP nodes, but not more sets - we flatten that
* out; while CUBE and ROLLUP can contain only SIMPLE nodes).
*
* We skip much of the hard work if there are no grouping sets.
*
* One subtlety is that the groupClause list can end up empty while the
* groupingSets list is not; this happens if there are only empty grouping
* sets, or an explicit GROUP BY (). This has the same effect as specifying
* aggregates or a HAVING clause with no GROUP BY; the output is one row per
* grouping set even if the input is empty.
*
* Returns the transformed (flat) groupClause.
*
* pstate ParseState
* grouplist clause to transform
* groupingSets reference to list to contain the grouping set tree
* targetlist reference to TargetEntry list
* sortClause ORDER BY clause (SortGroupClause nodes)
* exprKind expression kind
* useSQL99 SQL99 rather than SQL92 syntax
*/
List* transformGroupClause(
ParseState* pstate, List* grouplist, List** groupingSets, List** targetlist, List* sortClause, bool useSQL99)
{
List* result = NIL;
List* flat_grouplist = NIL;
List* gsets = NIL;
ListCell* gl = NULL;
bool hasGroupingSets = false;
Bitmapset* seen_local = NULL;
/*
* Recursively flatten implicit RowExprs. (Technically this is only needed
* for GROUP BY, per the syntax rules for grouping sets, but we do it
* anyway.)
*/
flat_grouplist = (List*)flatten_grouping_sets((Node*)grouplist, true, &hasGroupingSets);
/*
* If the list is now empty, but hasGroupingSets is true, it's because we
* elided redundant empty grouping sets. Restore a single empty grouping
* set to leave a canonical form: GROUP BY ()
*/
if (flat_grouplist == NIL && hasGroupingSets) {
flat_grouplist = list_make1(makeGroupingSet(GROUPING_SET_EMPTY, NIL, exprLocation((Node*)grouplist)));
}
foreach (gl, flat_grouplist) {
Node* gexpr = (Node*)lfirst(gl);
if (IsA(gexpr, GroupingSet)) {
GroupingSet* gset = (GroupingSet*)gexpr;
switch (gset->kind) {
case GROUPING_SET_EMPTY:
gsets = lappend(gsets, gset);
break;
case GROUPING_SET_SIMPLE:
/* can't happen */
Assert(false);
break;
case GROUPING_SET_SETS:
case GROUPING_SET_CUBE:
case GROUPING_SET_ROLLUP:
gsets = lappend(
gsets, transformGroupingSet(&result, pstate, gset, targetlist, sortClause, useSQL99, true));
break;
default:
break;
}
} else {
Index ref =
transformGroupClauseExpr(&result, seen_local, pstate, gexpr, targetlist, sortClause, useSQL99, true);
if (ref > 0) {
seen_local = bms_add_member(seen_local, ref);
if (hasGroupingSets) {
gsets =
lappend(gsets, makeGroupingSet(GROUPING_SET_SIMPLE, list_make1_int(ref), exprLocation(gexpr)));
}
}
}
}
/* parser should prevent this */
AssertEreport(gsets == NIL || groupingSets != NULL, MOD_OPT, "");
if (groupingSets != NULL) {
*groupingSets = gsets;
}
return result;
}
/*
* transformSortClause -
* transform an ORDER BY clause
*
* ORDER BY items will be added to the targetlist (as resjunk columns)
* if not already present, so the targetlist must be passed by reference.
*
* This is also used for window and aggregate ORDER BY clauses (which act
* almost the same, but are always interpreted per SQL99 rules).
*/
List* transformSortClause(ParseState* pstate, List* orderlist, List** targetlist, bool resolveUnknown, bool useSQL99)
{
List* sortlist = NIL;
ListCell* olitem = NULL;
foreach (olitem, orderlist) {
SortBy* sortby = (SortBy*)lfirst(olitem);
TargetEntry* tle = NULL;
if (useSQL99) {
tle = findTargetlistEntrySQL99(pstate, sortby->node, targetlist);
} else {
tle = findTargetlistEntrySQL92(pstate, sortby->node, targetlist, ORDER_CLAUSE);
}
sortlist = addTargetToSortList(pstate, tle, sortlist, *targetlist, sortby, resolveUnknown);
}
return sortlist;
}
/*
* transformWindowDefinitions -
* transform window definitions (WindowDef to WindowClause)
*/
List* transformWindowDefinitions(ParseState* pstate, List* windowdefs, List** targetlist)
{
List* result = NIL;
Index winref = 0;
ListCell* lc = NULL;
foreach (lc, windowdefs) {
WindowDef* windef = (WindowDef*)lfirst(lc);
WindowClause* refwc = NULL;
List* partitionClause = NIL;
List* orderClause = NIL;
WindowClause* wc = NULL;
winref++;
/*
* Check for duplicate window names.
*/
if (windef->name && findWindowClause(result, windef->name) != NULL) {
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("window \"%s\" is already defined", windef->name),
parser_errposition(pstate, windef->location)));
}
/*
* If it references a previous window, look that up.
*/
if (windef->refname) {
refwc = findWindowClause(result, windef->refname);
if (refwc == NULL) {
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("window \"%s\" does not exist", windef->refname),
parser_errposition(pstate, windef->location)));
}
}
/*
* Transform PARTITION and ORDER specs, if any. These are treated
* almost exactly like top-level GROUP BY and ORDER BY clauses,
* including the special handling of nondefault operator semantics.
*/
orderClause = transformSortClause(
pstate, windef->orderClause, targetlist, true /* fix unknowns */, true /* force SQL99 rules */);
partitionClause = transformGroupClause(
pstate, windef->partitionClause, NULL, targetlist, orderClause, true /* force SQL99 rules */);
/*
* And prepare the new WindowClause.
*/
wc = makeNode(WindowClause);
wc->name = windef->name;
wc->refname = windef->refname;
/*
* Per spec, a windowdef that references a previous one copies the
* previous partition clause (and mustn't specify its own). It can
* specify its own ordering clause. but only if the previous one had
* none. It always specifies its own frame clause, and the previous
* one must not have a frame clause. (Yeah, it's bizarre that each of
* these cases works differently, but SQL:2008 says so; see 7.11
* <window clause> syntax rule 10 and general rule 1.)
*/
if (refwc != NULL) {
if (partitionClause != NIL) {
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot override PARTITION BY clause of window \"%s\"", windef->refname),
parser_errposition(pstate, windef->location)));
}
wc->partitionClause = (List*)copyObject(refwc->partitionClause);
} else {
wc->partitionClause = partitionClause;
}
if (refwc != NULL) {
if (orderClause != NIL && refwc->orderClause != NIL)
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot override ORDER BY clause of window \"%s\"", windef->refname),
parser_errposition(pstate, windef->location)));
if (orderClause != NIL) {
wc->orderClause = orderClause;
wc->copiedOrder = false;
} else {
wc->orderClause = (List*)copyObject(refwc->orderClause);
wc->copiedOrder = true;
}
} else {
wc->orderClause = orderClause;
wc->copiedOrder = false;
}
if (refwc != NULL && refwc->frameOptions != FRAMEOPTION_DEFAULTS) {
ereport(ERROR,
(errcode(ERRCODE_WINDOWING_ERROR),
errmsg("cannot override frame clause of window \"%s\"", windef->refname),
parser_errposition(pstate, windef->location)));
}
wc->frameOptions = windef->frameOptions;
/* Process frame offset expressions */
wc->startOffset = transformFrameOffset(pstate, wc->frameOptions, windef->startOffset);
wc->endOffset = transformFrameOffset(pstate, wc->frameOptions, windef->endOffset);
wc->winref = winref;
result = lappend(result, wc);
}
return result;
}
/*
* transformDistinctClause -
* transform a DISTINCT clause
*
* Since we may need to add items to the query's targetlist, that list
* is passed by reference.
*
* As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
* possible into the distinctClause. This avoids a possible need to re-sort,
* and allows the user to choose the equality semantics used by DISTINCT,
* should she be working with a datatype that has more than one equality
* operator.
*
* is_agg is true if we are transforming an aggregate(DISTINCT ...)
* function call. This does not affect any behavior, only the phrasing
* of error messages.
*/
List* transformDistinctClause(ParseState* pstate, List** targetlist, List* sortClause, bool is_agg)
{
List* result = NIL;
ListCell* slitem = NULL;
ListCell* tlitem = NULL;
/*
* The distinctClause should consist of all ORDER BY items followed by all
* other non-resjunk targetlist items. There must not be any resjunk
* ORDER BY items --- that would imply that we are sorting by a value that
* isn't necessarily unique within a DISTINCT group, so the results
* wouldn't be well-defined. This construction ensures we follow the rule
* that sortClause and distinctClause match; in fact the sortClause will
* always be a prefix of distinctClause.
*
* Note a corner case: the same TLE could be in the ORDER BY list multiple
* times with different sortops. We have to include it in the
* distinctClause the same way to preserve the prefix property. The net
* effect will be that the TLE value will be made unique according to both
* sortops.
*/
foreach (slitem, sortClause) {
SortGroupClause* scl = (SortGroupClause*)lfirst(slitem);
TargetEntry* tle = get_sortgroupclause_tle(scl, *targetlist);
if (tle != NULL && tle->resjunk) {
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
is_agg ? errmsg("in an aggregate with DISTINCT, ORDER BY expressions must appear in argument list")
: errmsg("for SELECT DISTINCT, ORDER BY expressions must appear in select list"),
parser_errposition(pstate, exprLocation((Node*)tle->expr))));
}
result = lappend(result, copyObject(scl));
}
/*
* Now add any remaining non-resjunk tlist items, using default sort/group
* semantics for their data types.
*/
foreach (tlitem, *targetlist) {
TargetEntry* tle = (TargetEntry*)lfirst(tlitem);
if (tle != NULL && tle->resjunk) {
continue; /* ignore junk */
}
if (tle != NULL) {
result = addTargetToGroupList(pstate, tle, result, *targetlist, exprLocation((Node*)tle->expr), true);
}
else{
ereport(ERROR,
(errcode(ERRCODE_UNEXPECTED_NULL_VALUE), errmsg("invalid tle value")));
}
}
return result;
}
/*
* transformDistinctOnClause -
* transform a DISTINCT ON clause
*
* Since we may need to add items to the query's targetlist, that list
* is passed by reference.
*
* As with GROUP BY, we absorb the sorting semantics of ORDER BY as much as
* possible into the distinctClause. This avoids a possible need to re-sort,
* and allows the user to choose the equality semantics used by DISTINCT,
* should she be working with a datatype that has more than one equality
* operator.
*/
List* transformDistinctOnClause(ParseState* pstate, List* distinctlist, List** targetlist, List* sortClause)
{
List* result = NIL;
List* sortgrouprefs = NIL;
bool skipped_sortitem = false;
ListCell* lc = NULL;
ListCell* lc2 = NULL;
/*
* Add all the DISTINCT ON expressions to the tlist (if not already
* present, they are added as resjunk items). Assign sortgroupref numbers
* to them, and make a list of these numbers. (NB: we rely below on the
* sortgrouprefs list being one-for-one with the original distinctlist.
* Also notice that we could have duplicate DISTINCT ON expressions and
* hence duplicate entries in sortgrouprefs.)
*/
foreach (lc, distinctlist) {
Node* dexpr = (Node*)lfirst(lc);
int sortgroupref;
TargetEntry* tle = NULL;
tle = findTargetlistEntrySQL92(pstate, dexpr, targetlist, DISTINCT_ON_CLAUSE);
sortgroupref = assignSortGroupRef(tle, *targetlist);
sortgrouprefs = lappend_int(sortgrouprefs, sortgroupref);
}
/*
* If the user writes both DISTINCT ON and ORDER BY, adopt the sorting
* semantics from ORDER BY items that match DISTINCT ON items, and also
* adopt their column sort order. We insist that the distinctClause and
* sortClause match, so throw error if we find the need to add any more
* distinctClause items after we've skipped an ORDER BY item that wasn't
* in DISTINCT ON.
*/
skipped_sortitem = false;
foreach (lc, sortClause) {
SortGroupClause* scl = (SortGroupClause*)lfirst(lc);
if (list_member_int(sortgrouprefs, scl->tleSortGroupRef)) {
if (skipped_sortitem) {
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
parser_errposition(
pstate, get_matching_location(scl->tleSortGroupRef, sortgrouprefs, distinctlist))));
} else {
result = lappend(result, copyObject(scl));
}
} else {
skipped_sortitem = true;
}
}
/*
* Now add any remaining DISTINCT ON items, using default sort/group
* semantics for their data types. (Note: this is pretty questionable; if
* the ORDER BY list doesn't include all the DISTINCT ON items and more
* besides, you certainly aren't using DISTINCT ON in the intended way,
* and you probably aren't going to get consistent results. It might be
* better to throw an error or warning here. But historically we've
* allowed it, so keep doing so.)
*/
forboth(lc, distinctlist, lc2, sortgrouprefs)
{
Node* dexpr = (Node*)lfirst(lc);
int sortgroupref = lfirst_int(lc2);
TargetEntry* tle = get_sortgroupref_tle(sortgroupref, *targetlist);
if (targetIsInSortList(tle, InvalidOid, result)) {
continue; /* already in list (with some semantics) */
}
if (skipped_sortitem) {
ereport(ERROR,
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions"),
parser_errposition(pstate, exprLocation(dexpr))));
}
result = addTargetToGroupList(pstate, tle, result, *targetlist, exprLocation(dexpr), true);
}
return result;
}
/*
* getMatchingLocation
* Get the exprLocation of the exprs member corresponding to the
* (first) member of sortgrouprefs that equals sortgroupref.
*
* This is used so that we can point at a troublesome DISTINCT ON entry.
* (Note that we need to use the original untransformed DISTINCT ON list
* item, as whatever TLE it corresponds to will very possibly have a
* parse location pointing to some matching entry in the SELECT list
* or ORDER BY list.)
*/
static int get_matching_location(int sortgroupref, List* sortgrouprefs, List* exprs)
{
ListCell* lcs = NULL;
ListCell* lce = NULL;
forboth(lcs, sortgrouprefs, lce, exprs)
{
if (lfirst_int(lcs) == sortgroupref) {
return exprLocation((Node*)lfirst(lce));
}
}
/* if no match, caller blew it */
ereport(ERROR,
(errcode(ERRCODE_MOST_SPECIFIC_TYPE_MISMATCH), errmsg("get_matching_location: no matching sortgroupref")));
return -1; /* keep compiler quiet */
}
bool has_not_null_constraint(ParseState* pstate,TargetEntry* tle)
{
if(!IsA(tle->expr, Var))
return false;
Var* var =(Var*)tle->expr;
RangeTblEntry* rte = (RangeTblEntry*)linitial(pstate->p_rtable);
Oid reloid = rte->relid;
AttrNumber attno = var->varoattno;
if (reloid != InvalidOid && attno != InvalidAttrNumber) {
HeapTuple atttuple =
SearchSysCacheCopy2(ATTNUM, ObjectIdGetDatum(reloid), Int16GetDatum(attno));
if (!HeapTupleIsValid(atttuple)) {
Assert(0);
ereport(ERROR,
(errcode(ERRCODE_CACHE_LOOKUP_FAILED),
errmsg("cache lookup failed for attribute %u of relation %hd", reloid, attno)));
}
Form_pg_attribute attStruct = (Form_pg_attribute)GETSTRUCT(atttuple);
bool attHasNotNull = attStruct->attnotnull;
heap_freetuple_ext(atttuple);
return attHasNotNull;
}
return false;
}
bool is_single_table_query(ParseState* pstate)
{
if (list_length(pstate->p_rtable) != 1) {
return false;
}
RangeTblEntry* rte = (RangeTblEntry*)linitial(pstate->p_rtable);
if (rte->rtekind != RTE_RELATION) {
return false;
}
return true;
}
/*
* addTargetToSortList
* If the given targetlist entry isn't already in the SortGroupClause
* list, add it to the end of the list, using the given sort ordering
* info.
*
* If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not,
* do nothing (which implies the search for a sort operator will fail).
* pstate should be provided if resolveUnknown is TRUE, but can be NULL
* otherwise.
*
* Returns the updated SortGroupClause list.
*/
List* addTargetToSortList(
ParseState* pstate, TargetEntry* tle, List* sortlist, List* targetlist, SortBy* sortby, bool resolveUnknown)
{
Oid restype = exprType((Node*)tle->expr);
Oid sortop;
Oid eqop;
bool hashable = false;
bool reverse = false;
int location;
ParseCallbackState pcbstate;
/* if tlist item is an UNKNOWN literal, change it to TEXT */
if (restype == UNKNOWNOID && resolveUnknown) {
tle->expr = (Expr*)coerce_type(
pstate, (Node*)tle->expr, restype, TEXTOID, -1, COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
restype = TEXTOID;
}
/*
* Rather than clutter the API of get_sort_group_operators and the other
* functions we're about to use, make use of error context callback to
* mark any error reports with a parse position. We point to the operator
* location if present, else to the expression being sorted. (NB: use the
* original untransformed expression here; the TLE entry might well point
* at a duplicate expression in the regular SELECT list.)
*/
location = sortby->location;
if (location < 0) {
location = exprLocation(sortby->node);
}
setup_parser_errposition_callback(&pcbstate, pstate, location);
/* determine the sortop, eqop, and directionality */
switch (sortby->sortby_dir) {
case SORTBY_DEFAULT:
case SORTBY_ASC:
get_sort_group_operators(restype, true, true, false, &sortop, &eqop, NULL, &hashable);
reverse = false;
break;
case SORTBY_DESC:
get_sort_group_operators(restype, false, true, true, NULL, &eqop, &sortop, &hashable);
reverse = true;
break;
case SORTBY_USING:
AssertEreport(sortby->useOp != NIL, MOD_OPT, "para cannot be NIL");
sortop = compatible_oper_opid(sortby->useOp, restype, restype, false);
/*
* Verify it's a valid ordering operator, fetch the corresponding
* equality operator, and determine whether to consider it like
* ASC or DESC.
*/
eqop = get_equality_op_for_ordering_op(sortop, &reverse);
if (!OidIsValid(eqop)) {
ereport(ERROR,
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
errmsg("operator %s is not a valid ordering operator", strVal(llast(sortby->useOp))),
errhint("Ordering operators must be \"<\" or \">\" members of btree operator families.")));
}
/*
* Also see if the equality operator is hashable.
*/
hashable = op_hashjoinable(eqop, restype);
break;
default:
ereport(ERROR,
(errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE), errmsg("unrecognized sortby_dir: %d", sortby->sortby_dir)));
sortop = InvalidOid; /* keep compiler quiet */
eqop = InvalidOid;
hashable = false;
reverse = false;
break;
}
cancel_parser_errposition_callback(&pcbstate);
/* avoid making duplicate sortlist entries */
if (!targetIsInSortList(tle, sortop, sortlist)) {
SortGroupClause* sortcl = makeNode(SortGroupClause);
sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
sortcl->eqop = eqop;
sortcl->sortop = sortop;
sortcl->hashable = hashable;
/*
* For a single table query if the sorted column has constraints,
* we can remove NULLS LAST/FIRST to get a better plan.
* In some scenarios, we cannot optimize NULLS LAST/FIRST, such as the full outer join statement,
* because the processing process may complement the null value in the non-null constraint column.
* If NULLS LAST/FIRST is removed, the null value will be sorted incorrectly,
* so we only optimize the single table query.
*/
if (sortby->sortby_nulls != SORTBY_NULLS_DEFAULT && is_single_table_query(pstate) &&
has_not_null_constraint(pstate, tle)) {
sortby->sortby_nulls = SORTBY_NULLS_DEFAULT;
}
switch (sortby->sortby_nulls) {
case SORTBY_NULLS_DEFAULT:
/* NULLS FIRST is default for DESC; other way for ASC */
sortcl->nulls_first = reverse;
break;
case SORTBY_NULLS_FIRST:
sortcl->nulls_first = true;
break;
case SORTBY_NULLS_LAST:
sortcl->nulls_first = false;
break;
default:
ereport(ERROR,
(errcode(ERRCODE_UNEXPECTED_NODE_STATE),
errmsg("unrecognized sortby_nulls: %d", sortby->sortby_nulls)));
break;
}
sortlist = lappend(sortlist, sortcl);
}
return sortlist;
}
/*
* addTargetToGroupList
* If the given targetlist entry isn't already in the SortGroupClause
* list, add it to the end of the list, using default sort/group
* semantics.
*
* This is very similar to addTargetToSortList, except that we allow the
* case where only a grouping (equality) operator can be found, and that
* the TLE is considered "already in the list" if it appears there with any
* sorting semantics.
*
* location is the parse location to be fingered in event of trouble. Note
* that we can't rely on exprLocation(tle->expr), because that might point
* to a SELECT item that matches the GROUP BY item; it'd be pretty confusing
* to report such a location.
*
* If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not,
* do nothing (which implies the search for an equality operator will fail).
* pstate should be provided if resolveUnknown is TRUE, but can be NULL
* otherwise.
*
* Returns the updated SortGroupClause list.
*/
static List* addTargetToGroupList(
ParseState* pstate, TargetEntry* tle, List* grouplist, List* targetlist, int location, bool resolveUnknown)
{
Oid restype = exprType((Node*)tle->expr);
/* if tlist item is an UNKNOWN literal, change it to TEXT */
if (restype == UNKNOWNOID && resolveUnknown) {
tle->expr = (Expr*)coerce_type(
pstate, (Node*)tle->expr, restype, TEXTOID, -1, COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
restype = TEXTOID;
}
/* avoid making duplicate grouplist entries */
if (!targetIsInSortList(tle, InvalidOid, grouplist)) {
SortGroupClause* grpcl = makeNode(SortGroupClause);
Oid sortop;
Oid eqop;
bool hashable = false;
ParseCallbackState pcbstate;
setup_parser_errposition_callback(&pcbstate, pstate, location);
/* determine the eqop and optional sortop */
get_sort_group_operators(restype, false, true, false, &sortop, &eqop, NULL, &hashable);
cancel_parser_errposition_callback(&pcbstate);
grpcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
grpcl->eqop = eqop;
grpcl->sortop = sortop;
grpcl->nulls_first = false; /* OK with or without sortop */
grpcl->hashable = hashable;
grouplist = lappend(grouplist, grpcl);
}
return grouplist;
}
/*
* assignSortGroupRef
* Assign the targetentry an unused ressortgroupref, if it doesn't
* already have one. Return the assigned or pre-existing refnumber.
*
* 'tlist' is the targetlist containing (or to contain) the given targetentry.
*/
Index assignSortGroupRef(TargetEntry* tle, List* tlist)
{
Index maxRef;
ListCell* l = NULL;
if (tle->ressortgroupref) {
/* already has one? */
return tle->ressortgroupref;
}
/* easiest way to pick an unused refnumber: max used + 1 */
maxRef = 0;
foreach (l, tlist) {
Index ref = ((TargetEntry*)lfirst(l))->ressortgroupref;
if (ref > maxRef) {
maxRef = ref;
}
}
tle->ressortgroupref = maxRef + 1;
return tle->ressortgroupref;
}
/*
* targetIsInSortList
* Is the given target item already in the sortlist?
* If sortop is not InvalidOid, also test for a match to the sortop.
*
* It is not an oversight that this function ignores the nulls_first flag.
* We check sortop when determining if an ORDER BY item is redundant with
* earlier ORDER BY items, because it's conceivable that "ORDER BY
* foo USING <, foo USING <<<" is not redundant, if <<< distinguishes
* values that < considers equal. We need not check nulls_first
* however, because a lower-order column with the same sortop but
* opposite nulls direction is redundant. Also, we can consider
* ORDER BY foo ASC, foo DESC redundant, so check for a commutator match.
*
* Works for both ordering and grouping lists (sortop would normally be
* InvalidOid when considering grouping). Note that the main reason we need
* this routine (and not just a quick test for nonzeroness of ressortgroupref)
* is that a TLE might be in only one of the lists.
*/
bool targetIsInSortList(TargetEntry* tle, Oid sortop, List* sortList)
{
Index ref = tle->ressortgroupref;
ListCell* l = NULL;
/* no need to scan list if tle has no marker */
if (ref == 0)
return false;
foreach (l, sortList) {
SortGroupClause* scl = (SortGroupClause*)lfirst(l);
if (scl->tleSortGroupRef == ref &&
(sortop == InvalidOid || sortop == scl->sortop || sortop == get_commutator(scl->sortop))) {
return true;
}
}
return false;
}
/*
* findWindowClause
* Find the named WindowClause in the list, or return NULL if not there
*/
static WindowClause* findWindowClause(List* wclist, const char* name)
{
ListCell* l = NULL;
foreach (l, wclist) {
WindowClause* wc = (WindowClause*)lfirst(l);
if (wc->name && strcmp(wc->name, name) == 0) {
return wc;
}
}
return NULL;
}
/*
* transformFrameOffset
* Process a window frame offset expression
*/
static Node* transformFrameOffset(ParseState* pstate, int frameOptions, Node* clause)
{
const char* constructName = NULL;
Node* node = NULL;
/* Quick exit if no offset expression */
if (clause == NULL) {
return NULL;
}
/* Transform the raw expression tree */
node = transformExpr(pstate, clause);
if (frameOptions & FRAMEOPTION_ROWS) {
/*
* Like LIMIT clause, simply coerce to int8
*/
constructName = "ROWS";
node = coerce_to_specific_type(pstate, node, INT8OID, constructName);
} else if (frameOptions & FRAMEOPTION_RANGE) {
/*
* this needs a lot of thought to decide how to support in the context
* of Postgres' extensible datatype framework
*/
constructName = "RANGE";
/* error was already thrown by gram.y, this is just a backstop */
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("window frame with value offset is not implemented")));
} else {
Assert(false);
}
/* Disallow variables and aggregates in frame offsets */
checkExprIsVarFree(pstate, node, constructName);
return node;
}
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