greenplumn nodeValuesscan 源码
greenplumn nodeValuesscan 代码
文件路径:/src/backend/executor/nodeValuesscan.c
/*-------------------------------------------------------------------------
*
* nodeValuesscan.c
* Support routines for scanning Values lists
* ("VALUES (...), (...), ..." in rangetable).
*
* Portions Copyright (c) 2006-2008, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/executor/nodeValuesscan.c
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecValuesScan scans a values list.
* ExecValuesNext retrieve next tuple in sequential order.
* ExecInitValuesScan creates and initializes a valuesscan node.
* ExecEndValuesScan releases any storage allocated.
* ExecReScanValuesScan rescans the values list
*/
#include "postgres.h"
#include "executor/executor.h"
#include "executor/nodeValuesscan.h"
#include "jit/jit.h"
#include "utils/expandeddatum.h"
#include "cdb/cdbvars.h"
static TupleTableSlot *ValuesNext(ValuesScanState *node);
/* ----------------------------------------------------------------
* Scan Support
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ValuesNext
*
* This is a workhorse for ExecValuesScan
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ValuesNext(ValuesScanState *node)
{
TupleTableSlot *slot;
EState *estate;
ExprContext *econtext;
ScanDirection direction;
List *exprlist;
/*
* get information from the estate and scan state
*/
estate = node->ss.ps.state;
direction = estate->es_direction;
slot = node->ss.ss_ScanTupleSlot;
econtext = node->rowcontext;
/*
* Get the next tuple. Return NULL if no more tuples.
*/
if (ScanDirectionIsForward(direction))
{
if (node->curr_idx < node->array_len)
node->curr_idx++;
if (node->curr_idx < node->array_len)
exprlist = node->exprlists[node->curr_idx];
else
exprlist = NIL;
}
else
{
if (node->curr_idx >= 0)
node->curr_idx--;
if (node->curr_idx >= 0)
exprlist = node->exprlists[node->curr_idx];
else
exprlist = NIL;
}
/*
* Always clear the result slot; this is appropriate if we are at the end
* of the data, and if we're not, we still need it as the first step of
* the store-virtual-tuple protocol. It seems wise to clear the slot
* before we reset the context it might have pointers into.
*/
ExecClearTuple(slot);
if (exprlist)
{
MemoryContext oldContext;
List *oldsubplans;
List *exprstatelist;
Datum *values;
bool *isnull;
ListCell *lc;
int resind;
int saved_jit_flags;
/*
* Get rid of any prior cycle's leftovers. We use ReScanExprContext
* not just ResetExprContext because we want any registered shutdown
* callbacks to be called.
*/
ReScanExprContext(econtext);
/*
* Build the expression eval state in the econtext's per-tuple memory.
* This is a tad unusual, but we want to delete the eval state again
* when we move to the next row, to avoid growth of memory
* requirements over a long values list.
*/
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/*
* The expressions might contain SubPlans (this is currently only
* possible if there's a sub-select containing a LATERAL reference,
* otherwise sub-selects in a VALUES list should be InitPlans). Those
* subplans will want to hook themselves into our subPlan list, which
* would result in a corrupted list after we delete the eval state. We
* can work around this by saving and restoring the subPlan list.
* (There's no need for the functionality that would be enabled by
* having the list entries, since the SubPlans aren't going to be
* re-executed anyway.)
*/
oldsubplans = node->ss.ps.subPlan;
node->ss.ps.subPlan = NIL;
/*
* As the expressions are only ever used once, disable JIT for them.
* This is worthwhile because it's common to insert significant
* amounts of data via VALUES().
*/
saved_jit_flags = econtext->ecxt_estate->es_jit_flags;
econtext->ecxt_estate->es_jit_flags = PGJIT_NONE;
exprstatelist = ExecInitExprList(exprlist, &node->ss.ps);
econtext->ecxt_estate->es_jit_flags = saved_jit_flags;
node->ss.ps.subPlan = oldsubplans;
/* parser should have checked all sublists are the same length */
Assert(list_length(exprstatelist) == slot->tts_tupleDescriptor->natts);
/*
* Compute the expressions and build a virtual result tuple. We
* already did ExecClearTuple(slot).
*/
values = slot->tts_values;
isnull = slot->tts_isnull;
resind = 0;
foreach(lc, exprstatelist)
{
ExprState *estate = (ExprState *) lfirst(lc);
Form_pg_attribute attr = TupleDescAttr(slot->tts_tupleDescriptor,
resind);
values[resind] = ExecEvalExpr(estate,
econtext,
&isnull[resind]);
/*
* We must force any R/W expanded datums to read-only state, in
* case they are multiply referenced in the plan node's output
* expressions, or in case we skip the output projection and the
* output column is multiply referenced in higher plan nodes.
*/
values[resind] = MakeExpandedObjectReadOnly(values[resind],
isnull[resind],
attr->attlen);
resind++;
}
MemoryContextSwitchTo(oldContext);
/*
* And return the virtual tuple.
*/
ExecStoreVirtualTuple(slot);
}
return slot;
}
/*
* ValuesRecheck -- access method routine to recheck a tuple in EvalPlanQual
*/
static bool
ValuesRecheck(ValuesScanState *node, TupleTableSlot *slot)
{
/* nothing to check */
return true;
}
/* ----------------------------------------------------------------
* ExecValuesScan(node)
*
* Scans the values lists sequentially and returns the next qualifying
* tuple.
* We call the ExecScan() routine and pass it the appropriate
* access method functions.
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ExecValuesScan(PlanState *pstate)
{
ValuesScanState *node = castNode(ValuesScanState, pstate);
return ExecScan(&node->ss,
(ExecScanAccessMtd) ValuesNext,
(ExecScanRecheckMtd) ValuesRecheck);
}
/* ----------------------------------------------------------------
* ExecInitValuesScan
* ----------------------------------------------------------------
*/
ValuesScanState *
ExecInitValuesScan(ValuesScan *node, EState *estate, int eflags)
{
ValuesScanState *scanstate;
TupleDesc tupdesc;
ListCell *vtl;
int i;
PlanState *planstate;
/*
* ValuesScan should not have any children.
*/
Assert(outerPlan(node) == NULL);
Assert(innerPlan(node) == NULL);
/*
* create new ScanState for node
*/
scanstate = makeNode(ValuesScanState);
scanstate->ss.ps.plan = (Plan *) node;
scanstate->ss.ps.state = estate;
scanstate->ss.ps.ExecProcNode = ExecValuesScan;
/*
* Miscellaneous initialization
*/
planstate = &scanstate->ss.ps;
/*
* Create expression contexts. We need two, one for per-sublist
* processing and one for execScan.c to use for quals and projections. We
* cheat a little by using ExecAssignExprContext() to build both.
*/
ExecAssignExprContext(estate, planstate);
scanstate->rowcontext = planstate->ps_ExprContext;
ExecAssignExprContext(estate, planstate);
/*
* Get info about values list, initialize scan slot with it.
*/
tupdesc = ExecTypeFromExprList((List *) linitial(node->values_lists));
ExecInitScanTupleSlot(estate, &scanstate->ss, tupdesc, &TTSOpsVirtual);
/*
* Initialize result type and projection.
*/
ExecInitResultTypeTL(&scanstate->ss.ps);
ExecAssignScanProjectionInfo(&scanstate->ss);
/*
* initialize child expressions
*/
scanstate->ss.ps.qual =
ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
/*
* Other node-specific setup
*/
scanstate->curr_idx = -1;
scanstate->array_len = list_length(node->values_lists);
/* convert list of sublists into array of sublists for easy addressing */
scanstate->exprlists = (List **)
palloc(scanstate->array_len * sizeof(List *));
i = 0;
foreach(vtl, node->values_lists)
{
scanstate->exprlists[i++] = (List *) lfirst(vtl);
}
return scanstate;
}
/* ----------------------------------------------------------------
* ExecEndValuesScan
*
* frees any storage allocated through C routines.
* ----------------------------------------------------------------
*/
void
ExecEndValuesScan(ValuesScanState *node)
{
/*
* Free both exprcontexts
*/
ExecFreeExprContext(&node->ss.ps);
node->ss.ps.ps_ExprContext = node->rowcontext;
ExecFreeExprContext(&node->ss.ps);
/*
* clean out the tuple table
*/
if (node->ss.ps.ps_ResultTupleSlot)
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
ExecClearTuple(node->ss.ss_ScanTupleSlot);
}
/* ----------------------------------------------------------------
* ExecReScanValuesScan
*
* Rescans the relation.
* ----------------------------------------------------------------
*/
void
ExecReScanValuesScan(ValuesScanState *node)
{
if (node->ss.ps.ps_ResultTupleSlot)
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
ExecScanReScan(&node->ss);
node->curr_idx = -1;
}
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