greenplumn nodeMaterial 源码

  • 2022-08-18
  • 浏览 (432)

greenplumn nodeMaterial 代码

文件路径:/src/backend/executor/nodeMaterial.c

/*-------------------------------------------------------------------------
 *
 * nodeMaterial.c
 *	  Routines to handle materialization nodes.
 *
 * Portions Copyright (c) 2005-2008, 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/nodeMaterial.c
 *
 *-------------------------------------------------------------------------
 */
/*
 * INTERFACE ROUTINES
 *		ExecMaterial			- materialize the result of a subplan
 *		ExecInitMaterial		- initialize node and subnodes
 *		ExecEndMaterial			- shutdown node and subnodes
 *
 */
#include "postgres.h"

#include "executor/executor.h"
#include "executor/nodeMaterial.h"
#include "miscadmin.h"

#include "cdb/cdbvars.h"
#include "executor/instrument.h"        /* Instrumentation */

static void ExecMaterialExplainEnd(PlanState *planstate, struct StringInfoData *buf);
static void ExecChildRescan(MaterialState *node);

static void ExecEagerFreeMaterial(MaterialState *node);

/* ----------------------------------------------------------------
 *		ExecMaterial
 *
 *		As long as we are at the end of the data collected in the tuplestore,
 *		we collect one new row from the subplan on each call, and stash it
 *		aside in the tuplestore before returning it.  The tuplestore is
 *		only read if we are asked to scan backwards, rescan, or mark/restore.
 *
 * ----------------------------------------------------------------
 */
static TupleTableSlot *			/* result tuple from subplan */
ExecMaterial(PlanState *pstate)
{
	MaterialState *node = castNode(MaterialState, pstate);
	EState	   *estate;
	ScanDirection dir;
	bool		forward;
	Tuplestorestate *tuplestorestate;
	bool		eof_tuplestore;
	TupleTableSlot *slot;

	CHECK_FOR_INTERRUPTS();

	/*
	 * get state info from node
	 */
	estate = node->ss.ps.state;
	dir = estate->es_direction;
	forward = ScanDirectionIsForward(dir);
	tuplestorestate = node->tuplestorestate;

	/*
	 * If first time through, and we need a tuplestore, initialize it.
	 */
	if (tuplestorestate == NULL && node->eflags != 0)
	{
		tuplestorestate = tuplestore_begin_heap(true, false, PlanStateOperatorMemKB(&node->ss.ps));
		tuplestore_set_eflags(tuplestorestate, node->eflags);
		if (node->eflags & EXEC_FLAG_MARK)
		{
			/*
			 * Allocate a second read pointer to serve as the mark. We know it
			 * must have index 1, so needn't store that.
			 */
			int			ptrno PG_USED_FOR_ASSERTS_ONLY;

			ptrno = tuplestore_alloc_read_pointer(tuplestorestate,
												  node->eflags);
			Assert(ptrno == 1);
		}
		node->tuplestorestate = tuplestorestate;

        /* CDB: Offer extra info for EXPLAIN ANALYZE. */
        if (node->ss.ps.instrument && node->ss.ps.instrument->need_cdb)
        {
            /* Let the tuplestore share our Instrumentation object. */
			tuplestore_set_instrument(tuplestorestate, node->ss.ps.instrument);

            /* Request a callback at end of query. */
            node->ss.ps.cdbexplainfun = ExecMaterialExplainEnd;
        }

		/*
		 * MPP: If requested, fetch all rows from subplan and put them
		 * in the tuplestore.  This decouples a middle slice's receiving
		 * and sending Motion operators to neutralize a deadlock hazard.
		 * MPP TODO: Remove when a better solution is implemented.
		 *
		 * See motion_sanity_walker() for details on how a deadlock may occur.
		 */
		if (((Material *) node->ss.ps.plan)->cdb_strict)
		{
			for (;;)
			{
				TupleTableSlot *outerslot = ExecProcNode(outerPlanState(node));

				if (TupIsNull(outerslot))
					break;

				tuplestore_puttupleslot(tuplestorestate, outerslot);
			}
			node->eof_underlying = true;
			tuplestore_rescan(tuplestorestate);
		}
	}

	/*
	 * If we are not at the end of the tuplestore, or are going backwards, try
	 * to fetch a tuple from tuplestore.
	 */
	eof_tuplestore = (tuplestorestate == NULL) ||
		tuplestore_ateof(tuplestorestate);

	if (!forward && eof_tuplestore)
	{
		if (!node->eof_underlying)
		{
			/*
			 * When reversing direction at tuplestore EOF, the first
			 * gettupleslot call will fetch the last-added tuple; but we want
			 * to return the one before that, if possible. So do an extra
			 * fetch.
			 */
			if (!tuplestore_advance(tuplestorestate, forward))
				return NULL;	/* the tuplestore must be empty */
		}
		eof_tuplestore = false;
	}

	/*
	 * If we can fetch another tuple from the tuplestore, return it.
	 */
	slot = node->ss.ps.ps_ResultTupleSlot;
	if (!eof_tuplestore)
	{
		if (tuplestore_gettupleslot(tuplestorestate, forward, false, slot))
			return slot;
		if (forward)
			eof_tuplestore = true;
	}

	/*
	 * If necessary, try to fetch another row from the subplan.
	 *
	 * Note: the eof_underlying state variable exists to short-circuit further
	 * subplan calls.  It's not optional, unfortunately, because some plan
	 * node types are not robust about being called again when they've already
	 * returned NULL.
	 *
	 * GPDB: If reusing cached workfiles, there is no need to execute subplan
	 * at all.
	 */
	if (eof_tuplestore && !node->eof_underlying)
	{
		PlanState  *outerNode;
		TupleTableSlot *outerslot;

		/*
		 * We can only get here with forward==true, so no need to worry about
		 * which direction the subplan will go.
		 */
		outerNode = outerPlanState(node);
		outerslot = ExecProcNode(outerNode);
		if (TupIsNull(outerslot))
		{
			node->eof_underlying = true;
			if (!node->delayEagerFree)
			{
				ExecEagerFreeMaterial(node);
			}

			return NULL;
		}

		/*
		 * Append a copy of the returned tuple to tuplestore.  NOTE: because
		 * the tuplestore is certainly in EOF state, its read position will
		 * move forward over the added tuple.  This is what we want.
		 */
		if (tuplestorestate)
			tuplestore_puttupleslot(tuplestorestate, outerslot);

		ExecCopySlot(slot, outerslot);
		return slot;
	}

	if (!node->delayEagerFree)
	{
		ExecEagerFreeMaterial(node);
	}

	/*
	 * Nothing left ...
	 */
	return ExecClearTuple(slot);
}

/* ----------------------------------------------------------------
 *		ExecInitMaterial
 * ----------------------------------------------------------------
 */
MaterialState *
ExecInitMaterial(Material *node, EState *estate, int eflags)
{
	MaterialState *matstate;
	Plan	   *outerPlan;

	/*
	 * create state structure
	 */
	matstate = makeNode(MaterialState);
	matstate->ss.ps.plan = (Plan *) node;
	matstate->ss.ps.state = estate;
	matstate->ss.ps.ExecProcNode = ExecMaterial;

	if (node->cdb_strict)
		eflags |= EXEC_FLAG_REWIND;

	/*
	 * If the Material node was inserted to protect the child node from rescanning, don't
	 * eager free.
	 *
	 * XXX: The planner doesn't always set the flag for Material nodes that are put
	 * directly on top of Motion nodes, so check for that, too. (Or is this for ORCA?)
	 */
	if (node->cdb_shield_child_from_rescans ||
		IsA(outerPlan((Plan *) node), Motion))
	{
		eflags |= EXEC_FLAG_REWIND;
	}

	/*
	 * We must have a tuplestore buffering the subplan output to do backward
	 * scan or mark/restore.  We also prefer to materialize the subplan output
	 * if we might be called on to rewind and replay it many times. However,
	 * if none of these cases apply, we can skip storing the data.
	 */
	matstate->eflags = (eflags & (EXEC_FLAG_REWIND |
								  EXEC_FLAG_BACKWARD |
								  EXEC_FLAG_MARK));

	/*
	 * Tuplestore's interpretation of the flag bits is subtly different from
	 * the general executor meaning: it doesn't think BACKWARD necessarily
	 * means "backwards all the way to start".  If told to support BACKWARD we
	 * must include REWIND in the tuplestore eflags, else tuplestore_trim
	 * might throw away too much.
	 */
	if (eflags & EXEC_FLAG_BACKWARD)
		matstate->eflags |= EXEC_FLAG_REWIND;

	matstate->eof_underlying = false;
	matstate->tuplestorestate = NULL;
	matstate->ts_destroyed = false;

	/*
	 * Miscellaneous initialization
	 *
	 * Materialization nodes don't need ExprContexts because they never call
	 * ExecQual or ExecProject.
	 */

	/*
	 * If eflag contains EXEC_FLAG_REWIND or EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK,
	 * then this node is not eager free safe.
	 */
	matstate->delayEagerFree =
		((eflags & (EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)) != 0);

	/*
	 * initialize child nodes
	 *
	 * We shield the child node from the need to support BACKWARD, or
	 * MARK/RESTORE.
	 */
	eflags &= ~(EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);

	/*
	 * If Materialize does not have any external parameters, then it
	 * can shield the child node from being rescanned as well, hence
	 * we can clear the EXEC_FLAG_REWIND as well. If there are parameters,
	 * don't clear the REWIND flag, as the child will be rewound.
	 */
	if (node->plan.allParam == NULL || node->plan.extParam == NULL)
	{
		eflags &= ~EXEC_FLAG_REWIND;
	}

	outerPlan = outerPlan(node);
	/*
	 * A very basic check to see if the optimizer requires the material to do a projection.
	 * Ideally, this check would recursively compare all the target list expressions. However,
	 * such a check is tricky because of the varno mismatch (outer plan may have a varno that
	 * index into range table, while the material may refer to the same relation as "outer" varno)
	 * [JIRA: MPP-25365]
	 */
	if (list_length(node->plan.targetlist) != list_length(outerPlan->targetlist))
		elog(ERROR, "Material operator does not support projection");
	outerPlanState(matstate) = ExecInitNode(outerPlan, estate, eflags);

	/*
	 * Initialize result type and slot. No need to initialize projection info
	 * because this node doesn't do projections.
	 *
	 * material nodes only return tuples from their materialized relation.
	 */
	ExecInitResultTupleSlotTL(&matstate->ss.ps, &TTSOpsMinimalTuple);
	matstate->ss.ps.ps_ProjInfo = NULL;

	/*
	 * initialize tuple type.
	 */
	ExecCreateScanSlotFromOuterPlan(estate, &matstate->ss, &TTSOpsMinimalTuple);

	return matstate;
}

/*
 * ExecMaterialExplainEnd
 *      Called before ExecutorEnd to finish EXPLAIN ANALYZE reporting.
 *
 * Some of the cleanup that ordinarily would occur during ExecEndMaterial()
 * needs to be done earlier in order to report statistics to EXPLAIN ANALYZE.
 * Note that ExecEndMaterial() will be called again during ExecutorEnd().
 */
static void
ExecMaterialExplainEnd(PlanState *planstate, struct StringInfoData *buf)
{
	ExecEagerFreeMaterial((MaterialState*)planstate);
}                               /* ExecMaterialExplainEnd */


/* ----------------------------------------------------------------
 *		ExecEndMaterial
 * ----------------------------------------------------------------
 */
void
ExecEndMaterial(MaterialState *node)
{
	/*
	 * clean out the tuple table
	 */
	ExecClearTuple(node->ss.ss_ScanTupleSlot);

	/*
	 * Release tuplestore resources
	 */
	if (node->tuplestorestate != NULL)
	{
		tuplestore_end(node->tuplestorestate);
		node->ts_destroyed = true;
	}
	node->tuplestorestate = NULL;

	/*
	 * shut down the subplan
	 */
	ExecEndNode(outerPlanState(node));
}

/* ----------------------------------------------------------------
 *		ExecMaterialMarkPos
 *
 *		Calls tuplestore to save the current position in the stored file.
 * ----------------------------------------------------------------
 */
void
ExecMaterialMarkPos(MaterialState *node)
{
	Assert(node->eflags & EXEC_FLAG_MARK);

	/*
	 * if we haven't materialized yet, just return.
	 */
	if (!node->tuplestorestate)
		return;

	/*
	 * copy the active read pointer to the mark.
	 */
	tuplestore_copy_read_pointer(node->tuplestorestate, 0, 1);

	/*
	 * since we may have advanced the mark, try to truncate the tuplestore.
	 */
	tuplestore_trim(node->tuplestorestate);
}

/* ----------------------------------------------------------------
 *		ExecMaterialRestrPos
 *
 *		Calls tuplestore to restore the last saved file position.
 * ----------------------------------------------------------------
 */
void
ExecMaterialRestrPos(MaterialState *node)
{
	Assert(node->eflags & EXEC_FLAG_MARK);

	/*
	 * if we haven't materialized yet, just return.
	 */
	if (!node->tuplestorestate)
		return;

	/*
	 * copy the mark to the active read pointer.
	 */
	tuplestore_copy_read_pointer(node->tuplestorestate, 1, 0);
}

/*
 * ExecChildRescan
 *      Helper function for rescanning child of materialize node
 */
static void
ExecChildRescan(MaterialState *node)
{
	Assert(node);
	/*
	 * if parameters of subplan have changed, then subplan will be rescanned by
	 * first ExecProcNode. Otherwise, we need to rescan subplan here
	 */
	if (node->ss.ps.lefttree->chgParam == NULL)
		ExecReScan(node->ss.ps.lefttree);

	node->eof_underlying = false;
}

/* ----------------------------------------------------------------
 *		ExecReScanMaterial
 *
 *		Rescans the materialized relation.
 * ----------------------------------------------------------------
 */
void
ExecReScanMaterial(MaterialState *node)
{
	PlanState  *outerPlan = outerPlanState(node);

	ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);

	if (node->eflags != 0)
	{
		/*
		 * If tuple store is empty, then either we have not materialized yet
		 * or tuple store was destroyed after a previous execution of materialize.
		 */
		if (!node->tuplestorestate)
		{
			/*
			 *  If tuple store was destroyed before, then materialize is part of subquery
			 *  execution, and we need to rescan child (MPP-15087).
			 */
			if (node->ts_destroyed)
			{
				ExecChildRescan(node);
			}
			return;
		}

		/*
		 * If subnode is to be rescanned then we forget previous stored
		 * results; we have to re-read the subplan and re-store.  Also, if we
		 * told tuplestore it needn't support rescan, we lose and must
		 * re-read.  (This last should not happen in common cases; else our
		 * caller lied by not passing EXEC_FLAG_REWIND to us.)
		 *
		 * Otherwise we can just rewind and rescan the stored output. The
		 * state of the subnode does not change.
		 */
		if (outerPlan->chgParam != NULL ||
			(node->eflags & EXEC_FLAG_REWIND) == 0)
		{
			tuplestore_end(node->tuplestorestate);
			node->tuplestorestate = NULL;
			node->ts_destroyed = true;
			if (outerPlan->chgParam == NULL)
				ExecReScan(outerPlan);
			node->eof_underlying = false;
		}
		else
			tuplestore_rescan(node->tuplestorestate);
	}
	else
	{
		/* In this case we are just passing on the subquery's output */

		/*
		 * if chgParam of subnode is not null then plan will be re-scanned by
		 * first ExecProcNode.
		 */
		if (outerPlan->chgParam == NULL)
			ExecReScan(outerPlan);
		node->eof_underlying = false;
	}
}

static void
ExecEagerFreeMaterial(MaterialState *node)
{
	/*
	 * Release tuplestore resources
	 */
	if (node->tuplestorestate)
	{
		tuplestore_end(node->tuplestorestate);
		node->ts_destroyed = true;
	}
	node->tuplestorestate = NULL;
}

void
ExecSquelchMaterial(MaterialState *node)
{
	/*
	 * If this Material is shielding the underlying nodes from rescanning (for
	 * example, if there is a Motion node below), then keep the tuplestore.
	 * Also, don't recurse to the subtree in that case, because we might need
	 * to read more tuples from it after a ReScan. Most likely we have already
	 * read all the tuples from the underlying node in that case, but it's
	 * possible that ExecMaterial hasn't been called even once yet, and we
	 * haven't created the tuplestore yet.
	 */
	if (!node->delayEagerFree)
	{
		ExecEagerFreeMaterial(node);
		ExecSquelchNode(outerPlanState(node));
	}
}

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