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postgres/src/backend/executor/nodeTee.c

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/*-------------------------------------------------------------------------
*
* nodeTee.c--
*
*
* Copyright (c) 1994, Regents of the University of California
*
* DESCRIPTION
* This code provides support for a tee node, which allows multiple
* parent in a megaplan.
*
* INTERFACE ROUTINES
* ExecTee
* ExecInitTee
* ExecEndTee
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/Attic/nodeTee.c,v 1.5 1996/11/10 03:00:08 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <sys/file.h>
#include "postgres.h"
#include "utils/palloc.h"
#include "utils/relcache.h"
#include "utils/mcxt.h"
#include "storage/bufmgr.h" /* for IncrBufferRefCount */
#include "storage/smgr.h"
#include "optimizer/internal.h"
#include "executor/executor.h"
#include "executor/nodeTee.h"
#include "catalog/catalog.h"
#include "catalog/heap.h"
#include "tcop/pquery.h"
#include "access/heapam.h"
/* ------------------------------------------------------------------
* ExecInitTee
*
* Create tee state
*
* ------------------------------------------------------------------
*/
bool
ExecInitTee(Tee* node, EState *currentEstate, Plan * parent)
{
TeeState *teeState;
Plan *outerPlan;
int len;
Relation bufferRel;
TupleDesc tupType;
EState *estate;
/* it is possible that the Tee has already been initialized
since it can be reached by multiple parents.
If it is already initialized, simply return and do
not initialize the children nodes again
*/
if (node->plan.state)
return TRUE;
/* ----------------
* assign the node's execution state
* ----------------
*/
/* make a new executor state, because we have a different
es_range_table */
/* node->plan.state = estate;*/
estate = CreateExecutorState();
estate->es_direction = currentEstate->es_direction;
estate->es_BaseId = currentEstate->es_BaseId;
estate->es_BaseId = currentEstate->es_BaseId;
estate->es_tupleTable = currentEstate->es_tupleTable;
estate->es_refcount = currentEstate->es_refcount;
estate->es_junkFilter = currentEstate->es_junkFilter;
/* use the range table for Tee subplan since the range tables
for the two parents may be different */
if (node->rtentries)
estate->es_range_table = node->rtentries;
else
estate->es_range_table = currentEstate->es_range_table;
node->plan.state = estate;
/* ----------------
* create teeState structure
* ----------------
*/
teeState = makeNode(TeeState);
teeState->tee_leftPlace = 0;
teeState->tee_rightPlace = 0;
teeState->tee_lastPlace = 0;
teeState->tee_bufferRel = NULL;
teeState->tee_leftScanDesc = NULL;
teeState->tee_rightScanDesc = NULL;
node->teestate = teeState;
/* ----------------
* Miscellanious initialization
*
* + assign node's base_id
* + assign debugging hooks and
* + create expression context for node
* ----------------
*/
ExecAssignNodeBaseInfo(estate, &(teeState->cstate), parent);
ExecAssignExprContext(estate, &(teeState->cstate));
#define TEE_NSLOTS 2
/* ----------------
* initialize tuple slots
* ----------------
*/
ExecInitResultTupleSlot(estate, &(teeState->cstate));
/* initialize child nodes */
outerPlan = outerPlan((Plan*) node);
ExecInitNode(outerPlan, estate, (Plan*) node);
/* ----------------
* the tuple type info is from the outer plan of this node
* the result type is also the same as the outerplan
*/
ExecAssignResultTypeFromOuterPlan((Plan*) node, &(teeState->cstate));
ExecAssignProjectionInfo((Plan*)node, &teeState->cstate);
/* ---------------------------------------
initialize temporary relation to buffer tuples
*/
tupType = ExecGetResultType(&(teeState->cstate));
len = ExecTargetListLength(((Plan*)node)->targetlist);
/* bufferRel = ExecCreatR(len, tupType, _TEMP_RELATION_ID_); */
/* create a catalogued relation even though this is a temporary relation */
/* cleanup of catalogued relations is easier to do */
if (node->teeTableName[0] != '\0') {
Relation r;
teeState->tee_bufferRelname = pstrdup(node->teeTableName);
/* we are given an tee table name,
if a relation by that name exists, then we open it,
else we create it and then open it */
r = RelationNameGetRelation(teeState->tee_bufferRelname);
if (RelationIsValid(r))
bufferRel = heap_openr(teeState->tee_bufferRelname);
else
bufferRel = heap_open(heap_create(teeState->tee_bufferRelname,
/*FIX */ NULL,
'n',
DEFAULT_SMGR,
tupType));
}
else {
sprintf(teeState->tee_bufferRelname,
"ttemp_%d", /* 'ttemp' for 'tee' temporary*/
newoid());
/* bufferRel = ExecCreatR(len, tupType, _TEMP_RELATION_ID); */
bufferRel = heap_open(heap_create(teeState->tee_bufferRelname,
NULL, /*XXX */
'n',
DEFAULT_SMGR,
tupType));
}
teeState->tee_bufferRel = bufferRel;
/*initialize a memory context for allocating thing like scan descriptors */
/* we do this so that on cleanup of the tee, we can free things.
if we didn't have our own memory context, we would be in the memory
context of the portal that we happen to be using at the moment */
teeState->tee_mcxt = (MemoryContext)CreateGlobalMemory(teeState->tee_bufferRelname);
/* don't initialize the scan descriptors here
because it's not good to initialize scan descriptors on empty
rels. Wait until the scan descriptors are needed
before initializing them. */
teeState->tee_leftScanDesc = NULL;
teeState->tee_rightScanDesc = NULL;
return TRUE;
}
int
ExecCountSlotsTee(Tee *node)
{
/* Tee nodes can't have innerPlans */
return ExecCountSlotsNode(outerPlan(node)) + TEE_NSLOTS;
}
/* ----------------------------------------------------------------
initTeeScanDescs
initializes the left and right scandescs on the temporary
relation of a Tee node
must open two separate scan descriptors,
because the left and right scans may be at different points
* ----------------------------------------------------------------
*/
static void
initTeeScanDescs(Tee* node)
{
TeeState *teeState;
Relation bufferRel;
ScanDirection dir;
MemoryContext orig;
teeState = node->teestate;
if (teeState->tee_leftScanDesc && teeState->tee_rightScanDesc)
return;
orig = CurrentMemoryContext;
MemoryContextSwitchTo(teeState->tee_mcxt);
bufferRel = teeState->tee_bufferRel;
dir = ((Plan*)node)->state->es_direction; /* backwards not handled yet XXX */
if (teeState->tee_leftScanDesc == NULL)
{
teeState->tee_leftScanDesc = heap_beginscan(bufferRel,
ScanDirectionIsBackward(dir),
NowTimeQual, /* time qual */
0, /* num scan keys */
NULL /* scan keys */
);
}
if (teeState->tee_rightScanDesc == NULL)
{
teeState->tee_rightScanDesc = heap_beginscan(bufferRel,
ScanDirectionIsBackward(dir),
NowTimeQual, /* time qual */
0, /* num scan keys */
NULL /* scan keys */
);
}
MemoryContextSwitchTo(orig);
}
/* ----------------------------------------------------------------
* ExecTee(node)
*
*
* A Tee serves to connect a subplan to multiple parents.
* the subplan is always the outplan of the Tee node.
*
* The Tee gets requests from either leftParent or rightParent,
* fetches the result tuple from the child, and then
* stored the result into a temporary relation (serving as a queue).
* leftPlace and rightPlace keep track of where the left and rightParents
* are.
* If a parent requests a tuple and that parent is not at the end
* of the temporary relation, then the request is satisfied from
* the queue instead of by executing the child plan
*
* ----------------------------------------------------------------
*/
TupleTableSlot*
ExecTee(Tee *node, Plan *parent)
{
EState *estate;
TeeState *teeState;
int leftPlace, rightPlace, lastPlace;
int branch;
TupleTableSlot* result;
TupleTableSlot* slot;
Plan *childNode;
ScanDirection dir;
HeapTuple heapTuple;
Relation bufferRel;
HeapScanDesc scanDesc;
Buffer buffer;
estate = ((Plan*)node)->state;
teeState = node->teestate;
leftPlace = teeState->tee_leftPlace;
rightPlace = teeState->tee_rightPlace;
lastPlace = teeState->tee_lastPlace;
bufferRel = teeState->tee_bufferRel;
childNode = outerPlan(node);
dir = estate->es_direction;
/* XXX doesn't handle backwards direction yet */
if (parent == node->leftParent) {
branch = leftPlace;
}
else
if ( (parent == node->rightParent) || (parent == (Plan*) node))
/* the tee node could be the root node of the plan,
in which case, we treat it like a right-parent pull*/
{
branch = rightPlace;
}
else
{
elog(WARN,"A Tee node can only be executed from its left or right parent\n");
return NULL;
}
if (branch == lastPlace)
{ /* we're at the end of the queue already,
- get a new tuple from the child plan,
- store it in the queue,
- increment lastPlace,
- increment leftPlace or rightPlace as appropriate,
- and return result
*/
slot = ExecProcNode(childNode, (Plan*)node);
if (!TupIsNull(slot))
{
heapTuple = slot->val;
/* insert into temporary relation */
heap_insert(bufferRel, heapTuple);
/* once there is data in the temporary relation,
ensure that the left and right scandescs are initialized */
initTeeScanDescs(node);
scanDesc = (parent == node->leftParent) ?
teeState->tee_leftScanDesc : teeState->tee_rightScanDesc;
{
/* move the scandesc forward so we don't re-read this tuple later */
HeapTuple throwAway;
/* Buffer buffer;*/
throwAway = heap_getnext(scanDesc,
ScanDirectionIsBackward(dir),
/* &buffer */
(Buffer*)NULL);
}
/* set the shouldFree field of the child's slot so that
when the child's slot is free'd, this tuple isn't free'd also */
/* does this mean this tuple has to be garbage collected later??*/
slot->ttc_shouldFree = false;
teeState->tee_lastPlace = lastPlace + 1;
}
result = slot;
}
else
{/* the desired data already exists in the temporary relation */
scanDesc = (parent == node->leftParent) ?
teeState->tee_leftScanDesc : teeState->tee_rightScanDesc;
heapTuple = heap_getnext(scanDesc,
ScanDirectionIsBackward(dir),
&buffer);
/* Increase the pin count on the buffer page, because the
tuple stored in the slot also points to it (as well as
the scan descriptor). If we don't, ExecStoreTuple will
decrease the pin count on the next iteration. */
if (buffer != InvalidBuffer)
IncrBufferRefCount(buffer);
slot = teeState->cstate.cs_ResultTupleSlot;
slot->ttc_tupleDescriptor = RelationGetTupleDescriptor(bufferRel);
result = ExecStoreTuple(heapTuple,/* tuple to store */
slot, /* slot to store in */
buffer,/* this tuple's buffer */
false); /* don't free stuff from heap_getnext */
}
if (parent == node->leftParent)
{
teeState->tee_leftPlace = leftPlace+1;
}
else
{
teeState->tee_rightPlace = rightPlace+1;
}
return result;
}
/* ----------------------------------------------------------------
* ExecTeeReScan(node)
*
* Rescans the relation.
* ----------------------------------------------------------------
*/
void
ExecTeeReScan(Tee *node, ExprContext *exprCtxt, Plan *parent)
{
EState *estate;
TeeState *teeState;
ScanDirection dir;
estate = ((Plan*)node)->state;
teeState = node->teestate;
dir = estate->es_direction;
/* XXX doesn't handle backwards direction yet */
if (parent == node->leftParent) {
if (teeState->tee_leftScanDesc)
{
heap_rescan(teeState->tee_leftScanDesc,
ScanDirectionIsBackward(dir),
NULL);
teeState->tee_leftPlace = 0;
}
}
else
{
if (teeState->tee_rightScanDesc)
{
heap_rescan(teeState->tee_leftScanDesc,
ScanDirectionIsBackward(dir),
NULL);
teeState->tee_rightPlace = 0;
}
}
}
/* ---------------------------------------------------------------------
* ExecEndTee
*
* End the Tee node, and free up any storage
* since a Tee node can be downstream of multiple parent nodes,
* only free when both parents are done
* --------------------------------------------------------------------
*/
void
ExecEndTee(Tee* node, Plan* parent)
{
EState *estate;
TeeState *teeState;
int leftPlace, rightPlace, lastPlace;
Relation bufferRel;
MemoryContext orig;
estate = ((Plan*)node)->state;
teeState = node->teestate;
leftPlace = teeState->tee_leftPlace;
rightPlace = teeState->tee_rightPlace;
lastPlace = teeState->tee_lastPlace;
if (!node->leftParent || parent == node->leftParent)
leftPlace = -1;
if (!node->rightParent || parent == node->rightParent)
rightPlace = -1;
if (parent == (Plan*)node)
rightPlace = leftPlace = -1;
teeState->tee_leftPlace = leftPlace;
teeState->tee_rightPlace = rightPlace;
if ( (leftPlace == -1) && (rightPlace == -1) )
{
/* remove the temporary relations */
/* and close the scan descriptors */
bufferRel = teeState->tee_bufferRel;
if (bufferRel) {
heap_destroyr(bufferRel);
teeState->tee_bufferRel = NULL;
if (teeState->tee_mcxt) {
orig = CurrentMemoryContext;
MemoryContextSwitchTo(teeState->tee_mcxt);
}
else
orig = 0;
if (teeState->tee_leftScanDesc)
{
heap_endscan(teeState->tee_leftScanDesc);
teeState->tee_leftScanDesc = NULL;
}
if (teeState->tee_rightScanDesc)
{
heap_endscan(teeState->tee_rightScanDesc);
teeState->tee_rightScanDesc = NULL;
}
if (teeState->tee_mcxt) {
MemoryContextSwitchTo(orig);
teeState->tee_mcxt = NULL;
}
}
}
}
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