!284 rewrite ROWNUM to LIMIT if possible
Merge pull request !284 from 周雄佳/master
This commit is contained in:
opengauss-bot
@ -108,7 +108,6 @@ extern RangeTblEntry* make_dummy_remote_rte(char* relname, Alias* alias);
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extern List* reassign_nodelist(RangeTblEntry* rte, List* ori_node_list);
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extern Node* preprocess_expression(PlannerInfo* root, Node* expr, int kind);
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void preprocess_qual_conditions(PlannerInfo* root, Node* jtnode);
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static Plan* inheritance_planner(PlannerInfo* root);
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static Plan* grouping_planner(PlannerInfo* root, double tuple_fraction);
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static void preprocess_rowmarks(PlannerInfo* root);
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@ -1203,7 +1202,10 @@ Plan* subquery_planner(PlannerGlobal* glob, Query* parse, PlannerInfo* parent_ro
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if (parse->commandType == CMD_SELECT && checkSelectStmtForPlanTable(parse->rtable)) {
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OnlySelectFromPlanTable = true;
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}
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/* Change ROWNUM to LIMIT if possible */
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preprocess_rownum(root, parse);
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DEBUG_QRW("After preprocess rownum");
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/*
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* Check to see if any subqueries in the jointree can be merged into this
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* query.
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@ -1364,7 +1366,9 @@ Plan* subquery_planner(PlannerGlobal* glob, Query* parse, PlannerInfo* parent_ro
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}
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parse->limitOffset = preprocess_expression(root, parse->limitOffset, EXPRKIND_LIMIT);
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parse->limitCount = preprocess_expression(root, parse->limitCount, EXPRKIND_LIMIT);
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if (parse->limitCount != NULL && !IsA(parse->limitCount, Const)) {
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parse->limitCount = preprocess_expression(root, parse->limitCount, EXPRKIND_LIMIT);
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}
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foreach (l, parse->mergeActionList) {
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MergeAction* action = (MergeAction*)lfirst(l);
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@ -46,6 +46,9 @@
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#include "parser/parse_oper.h"
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#include "utils/lsyscache.h"
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#include "access/transam.h"
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#include "catalog/pg_operator.h"
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#include "nodes/pg_list.h"
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#include "optimizer/planner.h"
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typedef struct pullup_replace_vars_context {
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PlannerInfo* root;
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@ -88,8 +91,17 @@ static void fix_append_rel_relids(List* append_rel_list, int varno, Relids subre
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static Node* find_jointree_node_for_rel(Node* jtnode, int relid);
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static Node* deleteRelatedNullTest(Node* node, PlannerInfo* root);
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static Node* reduce_inequality_fulljoins_jointree_recurse(PlannerInfo* root, Node* jtnode);
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static bool find_rownum_in_quals(PlannerInfo *root);
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static bool process_rownum_opexpr(Query *parse, OpExpr *expr, bool isOrExpr);
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static Node *process_rownum_boolexpr(Query *parse, BoolExpr *quals, BoolExprType type);
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static bool process_rownum_opexpr_lessthan(Query *parse, Node *qual, int64 var, bool isOrExpr);
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static bool process_rownum_opexpr_lessthanEqual(Query *parse, Node *qual, int64 var, bool isOrExpr);
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static bool process_rownum_opexpr_Equal(Query *parse, Node *qual, int64 var, bool isOrExpr);
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static bool process_rownum_opexpr_greaterthan(Query *parse, Node *qual, int64 var, bool isOrExpr);
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static bool process_rownum_opexpr_greaterEqualthan(Query *parse, Node *qual, int64 var, bool isOrExpr);
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static bool process_rownum_opexpr_notEqual(Query *parse, Node *qual, int64 var, bool isOrExpr);
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static int64 get_constvalue_from_opexpr(OpExpr *expr);
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/*
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* pull_up_sublinks
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@ -1377,6 +1389,9 @@ static bool is_simple_subquery(Query* subquery)
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* that case the locking was originally declared in the upper query
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* anyway.
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*/
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if (verify_rownum_optimization_possibility(subquery)) {
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return false;
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}
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if (subquery->hasAggs || subquery->hasWindowFuncs || subquery->groupClause || subquery->groupingSets ||
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subquery->havingQual || subquery->sortClause || subquery->distinctClause || subquery->limitOffset ||
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subquery->limitCount || subquery->hasForUpdate || subquery->cteList)
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@ -1443,6 +1458,9 @@ static bool is_simple_union_all(Query* subquery)
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AssertEreport(
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IsA(topop, SetOperationStmt), MOD_OPT_REWRITE, "subquery's setOperations mismatch in is_simple_union_all");
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if (verify_rownum_optimization_possibility(subquery)) {
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return false;
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}
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/* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */
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if (subquery->sortClause || subquery->limitOffset || subquery->limitCount || subquery->rowMarks ||
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subquery->cteList)
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@ -2931,3 +2949,259 @@ static bool find_rownum_in_quals(PlannerInfo *root)
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return hasRownum;
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}
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/*
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* preprocess_rownum
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* change ROWNUM to LIMIT in parse tree if possible
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*/
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void preprocess_rownum(PlannerInfo *root, Query *parse)
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{
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if (!verify_rownum_optimization_possibility(parse)) {
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return;
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}
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if (parse->limitCount != NULL && !IsA(parse->limitCount, Const)) {
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parse->limitCount = eval_const_expressions(root, parse->limitCount);
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}
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Node *node = (Node *)parse->jointree->quals;
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if (node == NULL) {
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return;
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}
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switch (nodeTag(node)) {
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case T_OpExpr: {
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bool canBeOptimized = process_rownum_opexpr(parse, (OpExpr *)node, false);
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if (canBeOptimized) {
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free_quals(parse);
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}
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break;
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}
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case T_BoolExpr: {
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parse->jointree->quals = process_rownum_boolexpr(parse, (BoolExpr *)node, ((BoolExpr *)node)->boolop);
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break;
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}
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default: {
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break;
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}
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}
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}
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Node *process_rownum_boolexpr(Query *parse, BoolExpr *quals, BoolExprType type)
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{
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ListCell *qualCell = list_head(quals->args);
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ListCell *next = NULL;
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ListCell *prev = NULL;
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while (qualCell != NULL) {
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Node *clause = (Node *)lfirst(qualCell);
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next = lnext(qualCell);
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if (!IsA(clause, OpExpr)) {
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prev = qualCell;
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qualCell = next;
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continue;
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}
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OpExpr *expr = (OpExpr *)clause;
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bool canBeOptimized = false;
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if (type == AND_EXPR) {
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canBeOptimized = process_rownum_opexpr(parse, expr, false);
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} else {
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canBeOptimized = process_rownum_opexpr(parse, expr, true);
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}
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if (parse->jointree->quals == NULL) {
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return NULL;
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}
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if (canBeOptimized) {
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quals->args = list_delete_cell(quals->args, qualCell, prev);
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qualCell = next;
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continue;
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}
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prev = qualCell;
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qualCell = next;
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}
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return (Node *)quals;
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}
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static bool process_rownum_opexpr(Query *parse, OpExpr *expr, bool isOrExpr)
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{
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if (!contain_optimizable_rownum_opexpr(expr)) {
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return false;
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}
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int64 var = get_constvalue_from_opexpr(expr);
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Node *valueNode = (Node *)llast(expr->args);
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if (expr->opno == INT84LTOID) {
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/* operator '<' */
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return process_rownum_opexpr_lessthan(parse, valueNode, var, isOrExpr);
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} else if (expr->opno == INT84LEOID) {
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/* operator '<=' */
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return process_rownum_opexpr_lessthanEqual(parse, valueNode, var, isOrExpr);
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} else if (expr->opno == INT84EQOID) {
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/* operator '=' */
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return process_rownum_opexpr_Equal(parse, valueNode, var, isOrExpr);
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} else if (expr->opno == INT84GTOID) {
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/* operator '>' */
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return process_rownum_opexpr_greaterthan(parse, valueNode, var, isOrExpr);
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} else if (expr->opno == INT84GEOID) {
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/* operator '>=' */
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return process_rownum_opexpr_greaterEqualthan(parse, valueNode, var, isOrExpr);
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} else if (expr->opno == INT84NEOID) {
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/* operator '!=' */
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return process_rownum_opexpr_notEqual(parse, valueNode, var, isOrExpr);
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} else {
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return false;
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}
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}
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/* process operator '<' in rownum expr like {rownum < 5}
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* if it can be rewrited to LIMIT, return TRUE
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*/
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static bool process_rownum_opexpr_lessthan(Query *parse, Node *valueNode, int64 var, bool isOrExpr)
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{
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if (isOrExpr == false) {
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if (var > 1) {
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rewrite_rownum_to_limit(parse, valueNode, var - 1);
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} else {
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rewrite_rownum_to_limit(parse, valueNode, 0);
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free_quals(parse);
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return false;
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}
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} else {
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if (var > 1) {
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return false;
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}
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}
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return true;
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}
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/* process operator '<=' in rownum expr like {rownum <= 5}
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* if it can be rewrited to LIMIT, return TRUE
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*/
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static bool process_rownum_opexpr_lessthanEqual(Query *parse, Node *valueNode, int64 var, bool isOrExpr)
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{
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if (isOrExpr == false) {
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if (var >= 1) {
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rewrite_rownum_to_limit(parse, valueNode, var);
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} else {
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rewrite_rownum_to_limit(parse, valueNode, 0);
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free_quals(parse);
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return false;
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}
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} else {
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if (var >= 1) {
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return false;
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}
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}
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return true;
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}
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/* process operator '=' in rownum expr like {rownum = 5}
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* if it can be rewrited to LIMIT, return TRUE
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*/
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static bool process_rownum_opexpr_Equal(Query *parse, Node *valueNode, int64 var, bool isOrExpr)
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{
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if (isOrExpr == false) {
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if (var == 1) {
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rewrite_rownum_to_limit(parse, valueNode, 1);
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} else {
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rewrite_rownum_to_limit(parse, valueNode, 0);
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free_quals(parse);
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return false;
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}
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} else {
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if (var > 0) {
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return false;
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;
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}
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}
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return true;
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}
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/* process operator '>' in rownum expr like {rownum > 5}
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* if it can be rewrited to LIMIT, return TRUE
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*/
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static bool process_rownum_opexpr_greaterthan(Query *parse, Node *valueNode, int64 var, bool isOrExpr)
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{
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if (isOrExpr == false) {
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if (var >= 1) {
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rewrite_rownum_to_limit(parse, valueNode, 0);
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free_quals(parse);
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return false;
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}
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} else {
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if (var < 1) {
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free_quals(parse);
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}
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return false;
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}
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return true;
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}
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/* process operator '>=' in rownum expr like {rownum >= 5}
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* if it can be rewrited to LIMIT, return TRUE
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*/
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static bool process_rownum_opexpr_greaterEqualthan(Query *parse, Node *valueNode, int64 var, bool isOrExpr)
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{
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if (isOrExpr == false) {
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if (var > 1) {
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rewrite_rownum_to_limit(parse, valueNode, 0);
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free_quals(parse);
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return false;
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}
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} else {
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if (var <= 1) {
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free_quals(parse);
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}
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return false;
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}
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return true;
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}
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/* process operator '!=' in rownum expr like {rownum != 5}
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* if it can be rewrited to LIMIT, return TRUE
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*/
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static bool process_rownum_opexpr_notEqual(Query *parse, Node *valueNode, int64 var, bool isOrExpr)
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{
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if (isOrExpr == false) {
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if (var == 1) {
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rewrite_rownum_to_limit(parse, valueNode, 0);
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free_quals(parse);
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return false;
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} else if (var > 1) {
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rewrite_rownum_to_limit(parse, valueNode, var - 1);
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} else {
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/* nothing to do here */
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}
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} else {
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if (var < 1) {
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free_quals(parse);
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}
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return false;
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}
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return true;
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}
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/* extract const value from OpExpr like {rownum < Const} */
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static int64 get_constvalue_from_opexpr(OpExpr *expr)
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{
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Node *valueNode = (Node *)llast(expr->args);
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Oid type = ((Const *)valueNode)->consttype;
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Datum value = ((Const *)valueNode)->constvalue;
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int64 result;
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if (type == INT8OID) {
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result = DatumGetInt64(value);
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} else {
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result = (int64)DatumGetInt32(value);
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((Const *)valueNode)->consttype = INT8OID;
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((Const *)valueNode)->constlen = sizeof(int64);
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((Const *)valueNode)->constbyval = FLOAT8PASSBYVAL;
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}
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return result;
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}
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@ -70,6 +70,8 @@ extern bool plan_cluster_use_sort(Oid tableOid, Oid indexOid);
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extern bool ContainRecursiveUnionSubplan(PlannedStmt* pstmt);
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extern void preprocess_qual_conditions(PlannerInfo* root, Node* jtnode);
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typedef enum {
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/*
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* Disable "inlist2join" rewrite optimization
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@ -19,6 +19,8 @@
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#include "nodes/relation.h"
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#include "utils/guc.h"
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#include "catalog/pg_operator.h"
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#include "optimizer/clauses.h"
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/*
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* prototypes for prepjointree.c
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@ -26,51 +28,108 @@
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extern void pull_up_sublinks(PlannerInfo* root);
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extern void substitute_ctes_with_subqueries(PlannerInfo* root, Query* parse, bool under_recursive_tree);
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extern void inline_set_returning_functions(PlannerInfo* root);
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extern Node* pull_up_subqueries(
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PlannerInfo* root, Node* jtnode, JoinExpr* lowest_outer_join, AppendRelInfo* containing_appendrel);
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extern void flatten_simple_union_all(PlannerInfo* root);
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extern void removeNotNullTest(PlannerInfo* root);
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extern void reduce_outer_joins(PlannerInfo* root);
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extern void reduce_inequality_fulljoins(PlannerInfo* root);
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extern Relids get_relids_in_jointree(Node* jtnode, bool include_joins);
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extern Relids get_relids_for_join(PlannerInfo* root, int joinrelid);
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extern void pull_up_subquery_hint(PlannerInfo* root, Query* parse, HintState* hint_state);
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extern Node *pull_up_subqueries(PlannerInfo *root, Node *jtnode, JoinExpr *lowest_outer_join,
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AppendRelInfo *containing_appendrel);
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extern void flatten_simple_union_all(PlannerInfo *root);
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extern void removeNotNullTest(PlannerInfo *root);
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extern void reduce_outer_joins(PlannerInfo *root);
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extern void reduce_inequality_fulljoins(PlannerInfo *root);
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extern Relids get_relids_in_jointree(Node *jtnode, bool include_joins);
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extern Relids get_relids_for_join(PlannerInfo *root, int joinrelid);
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extern void pull_up_subquery_hint(PlannerInfo *root, Query *parse, HintState *hint_state);
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extern void preprocess_rownum(PlannerInfo *root, Query *parse);
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|
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/*
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* prototypes for prepnonjointree.cpp
|
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*/
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extern bool get_real_rte_varno_attno(
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Query* parse, Index* varno, AttrNumber* varattno, const Index targetVarno = InvalidOid);
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extern bool is_join_inner_side(
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const Node* fromNode, const Index targetRTEIndex, const bool isParentInnerSide, bool* isFound);
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extern Query* lazyagg_main(Query* parse);
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extern void reduce_orderby(Query* query, bool reduce);
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extern bool get_real_rte_varno_attno(Query *parse, Index *varno, AttrNumber *varattno,
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const Index targetVarno = InvalidOid);
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extern bool is_join_inner_side(const Node *fromNode, const Index targetRTEIndex, const bool isParentInnerSide,
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bool *isFound);
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extern Query *lazyagg_main(Query *parse);
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extern void reduce_orderby(Query *query, bool reduce);
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|
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extern Node* get_real_rte_varno_attno_or_node(Query* parse, Index* varno, AttrNumber* varattno);
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extern Node *get_real_rte_varno_attno_or_node(Query *parse, Index *varno, AttrNumber *varattno);
|
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|
||||
/*
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* prototypes for prepqual.c
|
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*/
|
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extern Node* negate_clause(Node* node);
|
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extern Expr* canonicalize_qual(Expr* qual);
|
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extern Node *negate_clause(Node *node);
|
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extern Expr *canonicalize_qual(Expr *qual);
|
||||
|
||||
/*
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* prototypes for preptlist.c
|
||||
*/
|
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extern List* preprocess_targetlist(PlannerInfo* root, List* tlist);
|
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extern List* preprocess_upsert_targetlist(List* tlist, int result_relation, List* range_table);
|
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extern PlanRowMark* get_plan_rowmark(List* rowmarks, Index rtindex);
|
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extern List *preprocess_targetlist(PlannerInfo *root, List *tlist);
|
||||
extern List *preprocess_upsert_targetlist(List *tlist, int result_relation, List *range_table);
|
||||
extern PlanRowMark *get_plan_rowmark(List *rowmarks, Index rtindex);
|
||||
|
||||
/*
|
||||
* prototypes for prepunion.c
|
||||
*/
|
||||
extern Plan* plan_set_operations(PlannerInfo* root, double tuple_fraction, List** sortClauses);
|
||||
extern Plan *plan_set_operations(PlannerInfo *root, double tuple_fraction, List **sortClauses);
|
||||
|
||||
extern void expand_inherited_tables(PlannerInfo* root);
|
||||
extern void make_inh_translation_list(
|
||||
Relation oldrelation, Relation newrelation, Index newvarno, List** translated_vars);
|
||||
extern Bitmapset* translate_col_privs(const Bitmapset* parent_privs, List* translated_vars);
|
||||
extern void expand_inherited_tables(PlannerInfo *root);
|
||||
extern void make_inh_translation_list(Relation oldrelation, Relation newrelation, Index newvarno,
|
||||
List **translated_vars);
|
||||
extern Bitmapset *translate_col_privs(const Bitmapset *parent_privs, List *translated_vars);
|
||||
|
||||
extern Node *adjust_appendrel_attrs(PlannerInfo *root, Node *node, AppendRelInfo *appinfo);
|
||||
|
||||
inline void free_quals(Query *parse)
|
||||
{
|
||||
pfree(parse->jointree->quals);
|
||||
parse->jointree->quals = NULL;
|
||||
}
|
||||
|
||||
/* judge if it is possible to optimize rownum */
|
||||
inline bool verify_rownum_optimization_possibility(Query *parse)
|
||||
{
|
||||
if (parse == NULL) {
|
||||
return false;
|
||||
}
|
||||
|
||||
if ((parse->commandType != CMD_SELECT) && (parse->commandType != CMD_INSERT) &&
|
||||
(parse->commandType != CMD_UPDATE) && (parse->commandType != CMD_DELETE)) {
|
||||
return false;
|
||||
}
|
||||
|
||||
if (!IsA((Node *)parse->jointree, FromExpr)) {
|
||||
return false;
|
||||
}
|
||||
|
||||
if (!contain_rownum_walker(((FromExpr *)parse->jointree)->quals, NULL)) {
|
||||
return false;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
inline bool contain_optimizable_rownum_opexpr(OpExpr *expr)
|
||||
{
|
||||
if (!IsA((Node *)linitial(expr->args), Rownum))
|
||||
return false;
|
||||
|
||||
if (!IsA((Node *)llast(expr->args), Const))
|
||||
return false;
|
||||
|
||||
if (((Const *)llast(expr->args))->consttype != INT8OID && ((Const *)llast(expr->args))->consttype != INT4OID) {
|
||||
return false;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
inline void rewrite_rownum_to_limit(Query *parse, Node *valueNode, int num)
|
||||
{
|
||||
((Const *)valueNode)->constvalue = num;
|
||||
if (parse->limitCount != NULL) {
|
||||
Const *Orin = (Const *)parse->limitCount;
|
||||
parse->limitCount = (Orin->constvalue < ((Const *)valueNode)->constvalue) ? (Node *)Orin : valueNode;
|
||||
} else {
|
||||
parse->limitCount = valueNode;
|
||||
}
|
||||
}
|
||||
|
||||
extern Node* adjust_appendrel_attrs(PlannerInfo* root, Node* node, AppendRelInfo* appinfo);
|
||||
|
||||
#endif /* PREP_H */
|
||||
|
||||
File diff suppressed because it is too large
Load Diff
@ -182,3 +182,240 @@ insert into bbbb values (0, 1);
|
||||
select (select a1.smgwname from aaaa a1 where a1.seid = ( select a2.seid from aaaa a2 where a2.igmgwidx = b.imgwindex and a2.imsflag = b.imsflag and rownum <=1)) from bbbb b;
|
||||
drop table aaaa;
|
||||
drop table bbbb;
|
||||
|
||||
--test query plan after optimizing
|
||||
create table student(id int, stuname varchar(10) );
|
||||
insert into student values(1, 'stu1');
|
||||
insert into student values(2, 'stu2');
|
||||
insert into student values(3, 'stu3');
|
||||
insert into student values(4, 'stu4');
|
||||
insert into student values(5, 'stu5');
|
||||
insert into student values(6, 'stu6');
|
||||
insert into student values(7, 'stu7');
|
||||
insert into student values(8, 'stu8');
|
||||
insert into student values(9, 'stu9');
|
||||
insert into student values(10, 'stu10');
|
||||
|
||||
create table test(id int, testchar varchar(10));
|
||||
insert into test values(1, 'test1');
|
||||
insert into test values(2, 'test2');
|
||||
insert into test values(3, 'test3');
|
||||
insert into test values(4, 'test4');
|
||||
insert into test values(5, 'test5');
|
||||
insert into test values(6, 'test6');
|
||||
insert into test values(7, 'test7');
|
||||
insert into test values(8, 'test8');
|
||||
insert into test values(9, 'test9');
|
||||
insert into test values(10, 'test10');
|
||||
|
||||
-- operator '<' (with 'and')
|
||||
-- n > 1
|
||||
explain select * from student where rownum < 5;
|
||||
explain select * from student where rownum < 5 and id > 5;
|
||||
explain select * from student where rownum < 5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum < 5 and rownum < 6;
|
||||
explain select * from student where rownum < 5 and rownum < 6 and rownum < 9;
|
||||
explain select * from student where rownum < 5 and rownum < 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
-- n <= 1
|
||||
explain select * from student where rownum < 1;
|
||||
explain select * from student where rownum < -5;
|
||||
explain select * from student where rownum < -5 and id > 5;
|
||||
explain select * from student where rownum < -5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum < -5 and rownum < 6;
|
||||
explain select * from student where rownum < -5 and rownum < 6 and rownum < 9;
|
||||
explain select * from student where rownum < -5 and rownum < 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
-- operator '<=' (with 'and')
|
||||
-- n >= 1
|
||||
explain select * from student where rownum <= 1;
|
||||
explain select * from student where rownum <= 5;
|
||||
explain select * from student where rownum <= 5 and id > 5;
|
||||
explain select * from student where rownum <= 5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum <= 5 and rownum < 6;
|
||||
explain select * from student where rownum <= 5 and rownum < 6 and rownum < 9;
|
||||
explain select * from student where rownum <= 5 and rownum < 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
-- n < 1
|
||||
explain select * from student where rownum <= -5;
|
||||
explain select * from student where rownum <= -5 and id > 5;
|
||||
explain select * from student where rownum <= -5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum <= -5 and rownum < 6;
|
||||
explain select * from student where rownum <= -5 and rownum < 6 and rownum < 9;
|
||||
explain select * from student where rownum <= -5 and rownum < 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
|
||||
-- operator '=' (with 'and')
|
||||
-- n = 1
|
||||
explain select * from student where rownum = 1;
|
||||
explain select * from student where rownum = 1 and id > 5;
|
||||
explain select * from student where rownum = 1 and rownum = 2 and id > 5;
|
||||
|
||||
-- n != 1
|
||||
explain select * from student where rownum = 2;
|
||||
explain select * from student where rownum = 2 and id > 5;
|
||||
|
||||
-- operator '!=' (with 'and')
|
||||
-- n = 1
|
||||
explain select * from student where rownum != 1;
|
||||
explain select * from student where rownum != 1 and id > 5;
|
||||
explain select * from student where rownum != 1 and rownum != 2 and id > 5;
|
||||
|
||||
-- n > 1
|
||||
explain select * from student where rownum != 5;
|
||||
explain select * from student where rownum != 5 and id > 5;
|
||||
explain select * from student where rownum != 5 and rownum != 8 and id > 5;
|
||||
|
||||
-- n < 1
|
||||
explain select * from student where rownum != -5;
|
||||
explain select * from student where rownum != -5 and id > 5;
|
||||
explain select * from student where rownum != -5 and rownum != -8 and id > 5;
|
||||
|
||||
-- operator '>' (with 'and')
|
||||
-- n >= 1
|
||||
explain select * from student where rownum > 1;
|
||||
explain select * from student where rownum > 5;
|
||||
explain select * from student where rownum > 5 and id > 5;
|
||||
explain select * from student where rownum > 5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum > 5 and rownum > 6;
|
||||
explain select * from student where rownum > 5 and rownum > 6 and rownum > 9;
|
||||
explain select * from student where rownum > 5 and rownum < 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
--n < 1
|
||||
explain select * from student where rownum > -5;
|
||||
explain select * from student where rownum > -5 and id > 5;
|
||||
explain select * from student where rownum > -5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum > -5 and rownum > 6;
|
||||
explain select * from student where rownum > -5 and rownum > 6 and rownum < 9;
|
||||
explain select * from student where rownum > -5 and rownum > 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
-- operator '>=' (with 'and')
|
||||
-- n > 1
|
||||
explain select * from student where rownum >= 5;
|
||||
explain select * from student where rownum >= 5 and id > 5;
|
||||
explain select * from student where rownum >= 5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum >= 5 and rownum > 6;
|
||||
explain select * from student where rownum >= 5 and rownum > 6 and rownum > 9;
|
||||
explain select * from student where rownum >= 5 and rownum < 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
-- n <= 1
|
||||
explain select * from student where rownum >= 1;
|
||||
explain select * from student where rownum >= -5;
|
||||
explain select * from student where rownum >= -5 and id > 5;
|
||||
explain select * from student where rownum >= -5 and id > 5 and id < 9;
|
||||
explain select * from student where rownum >= -5 and rownum > 6;
|
||||
explain select * from student where rownum >= -5 and rownum > 6 and rownum < 9;
|
||||
explain select * from student where rownum >= -5 and rownum > 6 and rownum < 9 and rownum < 12;
|
||||
|
||||
-- operator '<' with 'or'
|
||||
-- n > 1
|
||||
-- can not be optimized
|
||||
explain select * from student where rownum < 5 or id > 5;
|
||||
|
||||
-- n <= 1
|
||||
explain select * from student where rownum < -5;
|
||||
explain select * from student where rownum < -5 or id > 5;
|
||||
explain select * from student where rownum < -5 or id > 5 or id < 9;
|
||||
|
||||
-- operator '<=' with 'or'
|
||||
-- n >= 1
|
||||
-- can not be optimized
|
||||
explain select * from student where rownum <= 5 or id > 5;
|
||||
|
||||
-- n < 1
|
||||
explain select * from student where rownum <= -5;
|
||||
explain select * from student where rownum <= -5 or id > 5;
|
||||
explain select * from student where rownum <= -5 or id > 5 or id < 9;
|
||||
|
||||
-- operator '=' with 'or'
|
||||
-- n > 0
|
||||
-- can not be optimized
|
||||
explain select * from student where rownum = 5 or id > 5;
|
||||
|
||||
-- n <= 0
|
||||
explain select * from student where rownum = 0 or id > 5;
|
||||
explain select * from student where rownum = -1 or id > 5;
|
||||
|
||||
-- operator '!=' with 'or'
|
||||
-- n >= 1
|
||||
-- can not be optimized
|
||||
explain select * from student where rownum != 6 or id > 5;
|
||||
|
||||
-- n<1
|
||||
explain select * from student where rownum != 0 or id > 5;
|
||||
|
||||
-- operator '>' with 'or'
|
||||
-- n >= 1
|
||||
-- can not be optimized
|
||||
explain select * from student where rownum > 5 or id > 5;
|
||||
|
||||
-- n < 1
|
||||
explain select * from student where rownum > -5;
|
||||
explain select * from student where rownum > -5 or id > 5;
|
||||
explain select * from student where rownum > -5 or id > 5 or id < 9;
|
||||
-- operator '>=' with 'or'
|
||||
-- n > 1
|
||||
-- can not be optimized
|
||||
explain select * from student where rownum >= 5 or id > 5;
|
||||
|
||||
-- n <= 1
|
||||
explain select * from student where rownum >= -5;
|
||||
explain select * from student where rownum >= -5 or id > 5;
|
||||
explain select * from student where rownum >= -5 or id > 5 or id < 9;
|
||||
|
||||
-- limit
|
||||
explain select * from student where rownum < 5 limit 3;
|
||||
explain select * from student where rownum < 3 limit 5;
|
||||
explain select * from student where rownum <= 5 limit 3;
|
||||
explain select * from student where rownum <= 3 limit 5;
|
||||
|
||||
-- subqueries
|
||||
explain select * from (select * from student where rownum < 5);
|
||||
explain select * from (select * from student where rownum < 5) where rownum < 9;
|
||||
explain select * from (select * from student where rownum < 5 and id < 7);
|
||||
explain select * from (select * from student where rownum < 3 and id < 10) where rownum < 5;
|
||||
explain select * from (select * from student where rownum < 3 and id < 10) where rownum < 2 and stuname = 'stu1';
|
||||
|
||||
--sublink
|
||||
explain select * from student where id in (select id from test where rownum < 4);
|
||||
explain select * from student where id in (select id from test where rownum < 4) and rownum < 6;
|
||||
explain select * from student where id in (select id from test where rownum < 4) and stuname in (select stuname from student where rownum < 6);
|
||||
explain select * from student where id in (select id from test where rownum < 4 and id < 7);
|
||||
explain select * from student where id in (select id from test where rownum < 4) and rownum < 6 and id > 3;
|
||||
|
||||
-- insert
|
||||
explain insert into test select * from student where rownum < 5;
|
||||
explain insert into test select * from student where rownum < 5 and id > 3;
|
||||
|
||||
-- between
|
||||
explain select * from student where rownum between 1 and 5;
|
||||
explain select * from student where rownum between 2 and 8;
|
||||
explain select * from student where rownum between -5 and 8;
|
||||
explain select * from student where rownum between -5 and -2;
|
||||
|
||||
--update
|
||||
explain update student set id = 5 where rownum < 3;
|
||||
explain update student set id = 5 where rownum < 3 and rownum < 5;
|
||||
explain update student set id = 5 where rownum > 3;
|
||||
|
||||
--delete
|
||||
explain delete from student where rownum < 3;
|
||||
explain delete from student where rownum < 3 and rownum < 5;
|
||||
explain delete from student where rownum > 3;
|
||||
|
||||
-- have not been optimized yet
|
||||
explain select * from student where rownum < 6.5;
|
||||
explain select * from student where rownum <= 6.5;
|
||||
explain select * from student where rownum = 6.5;
|
||||
explain select * from student where rownum != 6.5;
|
||||
explain select * from student where rownum > 6.5;
|
||||
explain select * from student where rownum >= 6.5;
|
||||
|
||||
explain delete from student where 3 > rownum;
|
||||
explain delete from student where 3 < rownum;
|
||||
|
||||
explain delete from student where rownum < 5 or rownum < 6;
|
||||
explain delete from student where rownum > 5 or rownum > 6;
|
||||
|
||||
drop table student;
|
||||
drop table test;
|
||||
Reference in New Issue
Block a user