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first commit for openGauss server

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lishifu
2020-06-30 17:38:27 +08:00
parent bcb52078d5
commit 815a9771fb
7975 changed files with 9646516 additions and 61 deletions
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src/gausskernel/runtime/executor/execScan.cpp Executable file
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/* -------------------------------------------------------------------------
*
* execScan.cpp
* This code provides support for generalized relation scans. ExecScan
* is passed a node and a pointer to a function to "do the right thing"
* and return a tuple from the relation. ExecScan then does the tedious
* stuff - checking the qualification and projecting the tuple
* appropriately.
*
* Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/gausskernel/runtime/executor/execScan.cpp
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "knl/knl_variable.h"
#include "executor/executor.h"
#include "miscadmin.h"
#include "utils/memutils.h"
/*
* ExecScanFetch -- fetch next potential tuple
*
* This routine is concerned with substituting a test tuple if we are
* inside an EvalPlanQual recheck. If we aren't, just execute
* the access method's next-tuple routine.
*/
static TupleTableSlot* ExecScanFetch(ScanState* node, ExecScanAccessMtd access_mtd, ExecScanRecheckMtd recheck_mtd)
{
EState* e_state = node->ps.state;
if (e_state->es_epqTuple != NULL) {
/*
* We are inside an EvalPlanQual recheck. Return the test tuple if
* one is available, after rechecking any access-method-specific
* conditions.
*/
Index scan_rel_id = ((Scan*)node->ps.plan)->scanrelid;
Assert(scan_rel_id > 0);
if (e_state->es_epqTupleSet[scan_rel_id - 1]) {
TupleTableSlot* slot = node->ss_ScanTupleSlot;
/* Return empty slot if we already returned a tuple */
if (e_state->es_epqScanDone[scan_rel_id - 1])
return ExecClearTuple(slot);
/* Else mark to remember that we shouldn't return more */
e_state->es_epqScanDone[scan_rel_id - 1] = true;
/* Return empty slot if we haven't got a test tuple */
if (e_state->es_epqTuple[scan_rel_id - 1] == NULL)
return ExecClearTuple(slot);
/* Store test tuple in the plan node's scan slot */
(void)ExecStoreTuple(e_state->es_epqTuple[scan_rel_id - 1], slot, InvalidBuffer, false);
/* Check if it meets the access-method conditions */
if (!(*recheck_mtd)(node, slot))
(void)ExecClearTuple(slot); /* would not be returned by scan */
return slot;
}
}
/*
* Run the node-type-specific access method function to get the next tuple
*/
return (*access_mtd)(node);
}
/* ----------------------------------------------------------------
* ExecScan
*
* Scans the relation using the 'access method' indicated and
* returns the next qualifying tuple in the direction specified
* in the global variable ExecDirection.
* The access method returns the next tuple and execScan() is
* responsible for checking the tuple returned against the qual-clause.
*
* A 'recheck method' must also be provided that can check an
* arbitrary tuple of the relation against any qual conditions
* that are implemented internal to the access method.
*
* Conditions:
* -- the "cursor" maintained by the AMI is positioned at the tuple
* returned previously.
*
* Initial States:
* -- the relation indicated is opened for scanning so that the
* "cursor" is positioned before the first qualifying tuple.
* ----------------------------------------------------------------
*/
TupleTableSlot* ExecScan(ScanState* node, ExecScanAccessMtd access_mtd, /* function returning a tuple */
ExecScanRecheckMtd recheck_mtd)
{
ExprContext* e_context = NULL;
List* qual = NIL;
ProjectionInfo* proj_info = NULL;
ExprDoneCond is_done;
TupleTableSlot* result_slot = NULL;
if (node->isPartTbl && !PointerIsValid(node->partitions))
return NULL;
/*
* Fetch data from node
*/
qual = node->ps.qual;
proj_info = node->ps.ps_ProjInfo;
e_context = node->ps.ps_ExprContext;
/*
* If we have neither a qual to check nor a projection to do, just skip
* all the overhead and return the raw scan tuple.
*/
if (qual == NULL && proj_info == NULL) {
ResetExprContext(e_context);
return ExecScanFetch(node, access_mtd, recheck_mtd);
}
/*
* Check to see if we're still projecting out tuples from a previous scan
* tuple (because there is a function-returning-set in the projection
* expressions). If so, try to project another one.
*/
if (node->ps.ps_TupFromTlist) {
Assert(proj_info); /* can't get here if not projecting */
result_slot = ExecProject(proj_info, &is_done);
if (is_done == ExprMultipleResult)
return result_slot;
/* Done with that source tuple... */
node->ps.ps_TupFromTlist = false;
}
/*
* @hdfs
* Optimize scan bu using informational constraint.
* if the is_scan_false is true, the iteration is over.
*/
if (node->is_scan_end) {
return NULL;
}
/*
* Reset per-tuple memory context to free any expression evaluation
* storage allocated in the previous tuple cycle. Note this can't happen
* until we're done projecting out tuples from a scan tuple.
*/
ResetExprContext(e_context);
/*
* get a tuple from the access method. Loop until we obtain a tuple that
* passes the qualification.
*/
for (;;) {
TupleTableSlot* slot = NULL;
CHECK_FOR_INTERRUPTS();
slot = ExecScanFetch(node, access_mtd, recheck_mtd);
/* refresh qual every loop */
qual = node->ps.qual;
/*
* if the slot returned by the accessMtd contains NULL, then it means
* there is nothing more to scan so we just return an empty slot,
* being careful to use the projection result slot so it has correct
* tupleDesc.
*/
if (TupIsNull(slot) || unlikely(executorEarlyStop())) {
if (proj_info != NULL)
return ExecClearTuple(proj_info->pi_slot);
else
return slot;
}
/*
* place the current tuple into the expr context
*/
e_context->ecxt_scantuple = slot;
/*
* check that the current tuple satisfies the qual-clause
*
* check for non-nil qual here to avoid a function call to ExecQual()
* when the qual is nil ... saves only a few cycles, but they add up
* ...
*/
if (qual == NULL || ExecQual(qual, e_context, false)) {
/*
* Found a satisfactory scan tuple.
*/
if (proj_info != NULL) {
/*
* Form a projection tuple, store it in the result tuple slot
* and return it --- unless we find we can project no tuples
* from this scan tuple, in which case continue scan.
*/
result_slot = ExecProject(proj_info, &is_done);
#ifdef PGXC
/* Copy the xcnodeoid if underlying scanned slot has one */
result_slot->tts_xcnodeoid = slot->tts_xcnodeoid;
#endif /* PGXC */
if (is_done != ExprEndResult) {
node->ps.ps_TupFromTlist = (is_done == ExprMultipleResult);
/*
* @hdfs
* Optimize foreign scan by using informational constraint.
*/
if (IsA(node->ps.plan, ForeignScan)) {
ForeignScan* foreign_scan = (ForeignScan*)(node->ps.plan);
if (foreign_scan->scan.scan_qual_optimized) {
/*
* If we find a suitable tuple, set is_scan_end value is true.
* It means that we do not find suitable tuple in the next iteration,
* the iteration is over.
*/
node->is_scan_end = true;
}
}
return result_slot;
}
} else {
/*
* Optimize foreign scan by using informational constraint.
*/
if (IsA(node->ps.plan, ForeignScan)) {
ForeignScan* foreign_scan = (ForeignScan*)(node->ps.plan);
if (foreign_scan->scan.scan_qual_optimized) {
/*
* If we find a suitable tuple, set is_scan_end value is true.
* It means that we do not find suitable tuple in the next iteration,
* the iteration is over.
*/
node->is_scan_end = true;
}
}
/*
* Here, we aren't projecting, so just return scan tuple.
*/
return slot;
}
} else
InstrCountFiltered1(node, 1);
/*
* Tuple fails qual, so free per-tuple memory and try again.
*/
ResetExprContext(e_context);
}
}
/*
* ExecAssignScanProjectionInfo
* Set up projection info for a scan node, if necessary.
*
* We can avoid a projection step if the requested tlist exactly matches
* the underlying tuple type. If so, we just set ps_ProjInfo to NULL.
* Note that this case occurs not only for simple "SELECT * FROM ...", but
* also in most cases where there are joins or other processing nodes above
* the scan node, because the planner will preferentially generate a matching
* tlist.
*
* ExecAssignScanType must have been called already.
*/
void ExecAssignScanProjectionInfo(ScanState* node)
{
Scan* scan = (Scan*)node->ps.plan;
Index var_no;
/* Vars in an index-only scan's tlist should be INDEX_VAR */
if (IsA(scan, IndexOnlyScan))
var_no = INDEX_VAR;
else
var_no = scan->scanrelid;
if (tlist_matches_tupdesc(&node->ps, scan->plan.targetlist, var_no, node->ss_ScanTupleSlot->tts_tupleDescriptor))
node->ps.ps_ProjInfo = NULL;
else
ExecAssignProjectionInfo(&node->ps, node->ss_ScanTupleSlot->tts_tupleDescriptor);
}
/*
* ExecAssignScanProjectionInfoWithVarno
* As above, but caller can specify varno expected in Vars in the tlist.
* This function is called by ExecInitExtensiblePlan to initialize projection info.
* Usually the caller provides a targetlist describing the scan tuples, so we can
* avoid a projection step by setting ps_ProjInfo to NULL. Such as "SELECT * FROM ...".
*/
void ExecAssignScanProjectionInfoWithVarno(ScanState* node, Index var_no)
{
Scan* scan = (Scan*)node->ps.plan;
if (tlist_matches_tupdesc(&node->ps, scan->plan.targetlist, var_no, node->ss_ScanTupleSlot->tts_tupleDescriptor))
node->ps.ps_ProjInfo = NULL;
else
ExecAssignProjectionInfo(&node->ps, node->ss_ScanTupleSlot->tts_tupleDescriptor);
}
bool tlist_matches_tupdesc(PlanState* ps, List* t_list, Index var_no, TupleDesc tup_desc)
{
int num_attrs = tup_desc->natts;
int attr_no;
bool has_oid = false;
ListCell* t_list_item = list_head(t_list);
/* Check the tlist attributes */
for (attr_no = 1; attr_no <= num_attrs; attr_no++) {
Form_pg_attribute att_tup = tup_desc->attrs[attr_no - 1];
Var* var = NULL;
if (t_list_item == NULL)
return false; /* tlist too short */
var = (Var*)((TargetEntry*)lfirst(t_list_item))->expr;
if (var == NULL || !IsA(var, Var))
return false; /* tlist item not a Var */
/* if these Asserts fail, planner messed up */
Assert(var->varno == var_no);
Assert(var->varlevelsup == 0);
if (var->varattno != attr_no)
return false; /* out of order */
if (att_tup->attisdropped)
return false; /* table contains dropped columns */
/*
* Note: usually the Var's type should match the tupdesc exactly, but
* in situations involving unions of columns that have different
* typmods, the Var may have come from above the union and hence have
* typmod -1. This is a legitimate situation since the Var still
* describes the column, just not as exactly as the tupdesc does. We
* could change the planner to prevent it, but it'd then insert
* projection steps just to convert from specific typmod to typmod -1,
* which is pretty silly.
*/
if (var->vartype != att_tup->atttypid || (var->vartypmod != att_tup->atttypmod && var->vartypmod != -1))
return false; /* type mismatch */
t_list_item = lnext(t_list_item);
}
if (t_list_item != NULL)
return false; /* tlist too long */
/*
* If the plan context requires a particular hasoid setting, then that has
* to match, too.
*/
if (ExecContextForcesOids(ps, &has_oid) && has_oid != tup_desc->tdhasoid)
return false;
return true;
}
/*
* ExecScanReScan
*
* This must be called within the ReScan function of any plan node type
* that uses ExecScan().
*/
void ExecScanReScan(ScanState* node)
{
EState* e_state = node->ps.state;
/* Stop projecting any tuples from SRFs in the targetlist */
node->ps.ps_TupFromTlist = false;
/* Rescan EvalPlanQual tuple if we're inside an EvalPlanQual recheck */
if (e_state->es_epqScanDone != NULL) {
Index scan_rel_id = ((Scan*)node->ps.plan)->scanrelid;
Assert(scan_rel_id > 0);
e_state->es_epqScanDone[scan_rel_id - 1] = false;
}
}