greenplumn nodeValuesscan 源码

  • 2022-08-18
  • 浏览 (623)

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;
}

相关信息

greenplumn 源码目录

相关文章

greenplumn execAmi 源码

greenplumn execCurrent 源码

greenplumn execExpr 源码

greenplumn execExprInterp 源码

greenplumn execGrouping 源码

greenplumn execIndexing 源码

greenplumn execJunk 源码

greenplumn execMain 源码

greenplumn execParallel 源码

greenplumn execPartition 源码

0  赞