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Tid access method feature from Hiroshi Inoue, Inoue@tpf.co.jp
This commit is contained in:
Bruce Momjian
550
src/backend/executor/nodeTidscan.c
Normal file
550
src/backend/executor/nodeTidscan.c
Normal file
@ -0,0 +1,550 @@
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/*-------------------------------------------------------------------------
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*
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* nodeTidscan.c
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* Routines to support direct tid scans of relations
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/executor/nodeTidscan.c,v 1.1 1999/11/23 20:06:51 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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/*
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* INTERFACE ROUTINES
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*
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* ExecTidScan scans a relation using tids
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* ExecInitTidScan creates and initializes state info.
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* ExecTidReScan rescans the tid relation.
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* ExecEndTidScan releases all storage.
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* ExecTidMarkPos marks scan position.
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* ExecTidRestrPos restores scan position.
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*
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*/
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#include "postgres.h"
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#include "executor/executor.h"
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#include "executor/execdebug.h"
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#include "executor/nodeTidscan.h"
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#include "optimizer/clauses.h" /* for get_op, get_leftop, get_rightop */
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#include "access/heapam.h"
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#include "parser/parsetree.h"
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static int TidListCreate(List *, ExprContext *, ItemPointer *);
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static TupleTableSlot *TidNext(TidScan *node);
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static int
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TidListCreate(List *evalList, ExprContext *econtext, ItemPointer *tidList)
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{
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List *lst;
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ItemPointer itemptr;
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bool isNull;
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int numTids = 0;
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foreach (lst, evalList)
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{
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itemptr = (ItemPointer)ExecEvalExpr(lfirst(lst), econtext,
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&isNull, (bool *)0);
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if (itemptr && ItemPointerIsValid(itemptr))
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{
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tidList[numTids] = itemptr;
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numTids++;
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}
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}
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return numTids;
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}
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/* ----------------------------------------------------------------
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* TidNext
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*
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* Retrieve a tuple from the TidScan node's currentRelation
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* using the tids in the TidScanState information.
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*
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* ----------------------------------------------------------------
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*/
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static TupleTableSlot *
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TidNext(TidScan *node)
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{
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EState *estate;
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CommonScanState *scanstate;
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TidScanState *tidstate;
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ScanDirection direction;
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Snapshot snapshot;
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Relation heapRelation;
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HeapTuple tuple;
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TupleTableSlot *slot;
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Buffer buffer = InvalidBuffer;
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int numTids;
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bool bBackward;
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int tidNumber;
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ItemPointer *tidList, itemptr;
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/* ----------------
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* extract necessary information from tid scan node
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* ----------------
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*/
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estate = node->scan.plan.state;
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direction = estate->es_direction;
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snapshot = estate->es_snapshot;
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scanstate = node->scan.scanstate;
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tidstate = node->tidstate;
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heapRelation = scanstate->css_currentRelation;
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numTids = tidstate->tss_NumTids;
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tidList = tidstate->tss_TidList;
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slot = scanstate->css_ScanTupleSlot;
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/*
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* Check if we are evaluating PlanQual for tuple of this relation.
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* Additional checking is not good, but no other way for now. We could
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* introduce new nodes for this case and handle TidScan --> NewNode
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* switching in Init/ReScan plan...
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*/
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if (estate->es_evTuple != NULL &&
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estate->es_evTuple[node->scan.scanrelid - 1] != NULL)
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{
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int iptr, numQuals;
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ExecClearTuple(slot);
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if (estate->es_evTupleNull[node->scan.scanrelid - 1])
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return slot; /* return empty slot */
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slot->val = estate->es_evTuple[node->scan.scanrelid - 1];
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slot->ttc_shouldFree = false;
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/* Flag for the next call that no more tuples */
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estate->es_evTupleNull[node->scan.scanrelid - 1] = true;
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return (slot);
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}
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tuple = &(tidstate->tss_htup);
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/* ----------------
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* ok, now that we have what we need, fetch an tid tuple.
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* if scanning this tid succeeded then return the
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* appropriate heap tuple.. else return NULL.
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* ----------------
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*/
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bBackward = ScanDirectionIsBackward(direction);
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if (bBackward)
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{
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tidNumber = numTids - tidstate->tss_TidPtr - 1;
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if (tidNumber < 0)
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{
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tidNumber = 0;
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tidstate->tss_TidPtr = numTids - 1;
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}
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}
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else
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{
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if ((tidNumber = tidstate->tss_TidPtr) < 0)
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{
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tidNumber = 0;
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tidstate->tss_TidPtr = 0;
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}
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}
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while (tidNumber < numTids)
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{
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bool slot_is_valid = false;
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itemptr = tidList[tidstate->tss_TidPtr];
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tuple->t_data = NULL;
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if (itemptr)
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{
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tuple->t_self = *(itemptr);
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heap_fetch(heapRelation, snapshot, tuple, &buffer);
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}
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if (tuple->t_data != NULL)
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{
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bool prev_matches = false;
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int prev_tid;
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/* ----------------
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* store the scanned tuple in the scan tuple slot of
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* the scan state. Eventually we will only do this and not
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* return a tuple. Note: we pass 'false' because tuples
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* returned by amgetnext are pointers onto disk pages and
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* were not created with palloc() and so should not be pfree()'d.
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* ----------------
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*/
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ExecStoreTuple(tuple, /* tuple to store */
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slot, /* slot to store in */
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buffer, /* buffer associated with tuple */
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false); /* don't pfree */
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/*
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* At this point we have an extra pin on the buffer,
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* because ExecStoreTuple incremented the pin count.
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* Drop our local pin.
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*/
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ReleaseBuffer(buffer);
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/*
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* We must check to see if the current tuple would have
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* been matched by an earlier tid, so we don't double
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* report it. We do this by passing the tuple through
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* ExecQual and look for failure with all previous
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* qualifications.
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*/
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for (prev_tid = 0; prev_tid < tidstate->tss_TidPtr;
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prev_tid++)
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{
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if (ItemPointerEquals(tidList[prev_tid], &tuple->t_self))
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{
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prev_matches = true;
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break;
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}
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}
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if (!prev_matches)
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slot_is_valid = true;
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else
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ExecClearTuple(slot);
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}
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else if (BufferIsValid(buffer))
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ReleaseBuffer(buffer);
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tidNumber++;
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if (bBackward)
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tidstate->tss_TidPtr--;
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else
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tidstate->tss_TidPtr++;
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if (slot_is_valid)
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return slot;
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}
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/* ----------------
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* if we get here it means the tid scan failed so we
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* are at the end of the scan..
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* ----------------
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*/
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return ExecClearTuple(slot);
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}
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/* ----------------------------------------------------------------
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* ExecTidScan(node)
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*
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* Scans the relation using tids and returns
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* the next qualifying tuple in the direction specified.
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* It calls ExecScan() and passes it the access methods which returns
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* the next tuple using the tids.
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*
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* Conditions:
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* -- the "cursor" maintained by the AMI is positioned at the tuple
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* returned previously.
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*
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* Initial States:
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* -- the relation indicated is opened for scanning so that the
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* "cursor" is positioned before the first qualifying tuple.
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* -- tidPtr points to the first tid.
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* -- state variable ruleFlag = nil.
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* ----------------------------------------------------------------
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*/
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TupleTableSlot *
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ExecTidScan(TidScan *node)
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{
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/* ----------------
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* use TidNext as access method
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* ----------------
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*/
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return ExecScan(&node->scan, TidNext);
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}
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/* ----------------------------------------------------------------
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* ExecTidReScan(node)
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* ----------------------------------------------------------------
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*/
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void
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ExecTidReScan(TidScan *node, ExprContext *exprCtxt, Plan *parent)
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{
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EState *estate;
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TidScanState *tidstate;
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Plan *outerPlan;
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ItemPointer *tidList;
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tidstate = node->tidstate;
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estate = node->scan.plan.state;
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tidstate->tss_TidPtr = -1;
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tidList = tidstate->tss_TidList;
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if ((outerPlan = outerPlan((Plan *) node)) != NULL)
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{
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/* we are scanning a subplan */
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outerPlan = outerPlan((Plan *) node);
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ExecReScan(outerPlan, exprCtxt, parent);
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}
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else
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/* otherwise, we are scanning a relation */
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{
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/* If this is re-scanning of PlanQual ... */
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if (estate->es_evTuple != NULL &&
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estate->es_evTuple[node->scan.scanrelid - 1] != NULL)
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{
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estate->es_evTupleNull[node->scan.scanrelid - 1] = false;
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return;
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}
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/* it's possible in subselects */
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if (exprCtxt == NULL)
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exprCtxt = node->scan.scanstate->cstate.cs_ExprContext;
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node->scan.scanstate->cstate.cs_ExprContext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
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tidstate->tss_NumTids = TidListCreate(node->tideval, exprCtxt, tidList);
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}
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/* ----------------
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* perhaps return something meaningful
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* ----------------
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*/
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return;
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}
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/* ----------------------------------------------------------------
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* ExecEndTidScan
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*
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* Releases any storage allocated through C routines.
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* Returns nothing.
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* ----------------------------------------------------------------
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*/
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void
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ExecEndTidScan(TidScan *node)
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{
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CommonScanState *scanstate;
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TidScanState *tidstate;
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scanstate = node->scan.scanstate;
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tidstate = node->tidstate;
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if (tidstate && tidstate->tss_TidList)
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pfree(tidstate->tss_TidList);
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/* ----------------
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* extract information from the node
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* ----------------
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*/
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/* ----------------
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* Free the projection info and the scan attribute info
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*
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* Note: we don't ExecFreeResultType(scanstate)
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* because the rule manager depends on the tupType
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* returned by ExecMain(). So for now, this
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* is freed at end-transaction time. -cim 6/2/91
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* ----------------
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*/
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ExecFreeProjectionInfo(&scanstate->cstate);
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/* ----------------
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* close the heap and tid relations
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* ----------------
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*/
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ExecCloseR((Plan *) node);
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/* ----------------
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* clear out tuple table slots
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* ----------------
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*/
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ExecClearTuple(scanstate->cstate.cs_ResultTupleSlot);
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ExecClearTuple(scanstate->css_ScanTupleSlot);
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/* ExecClearTuple(scanstate->css_RawTupleSlot); */
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}
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/* ----------------------------------------------------------------
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* ExecTidMarkPos
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*
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* Marks scan position by marking the current tid.
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* Returns nothing.
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* ----------------------------------------------------------------
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*/
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void
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ExecTidMarkPos(TidScan *node)
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{
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TidScanState *tidstate;
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tidstate = node->tidstate;
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tidstate->tss_MarkTidPtr = tidstate->tss_TidPtr;
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}
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/* ----------------------------------------------------------------
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* ExecTidRestrPos
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*
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* Restores scan position by restoring the current tid.
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* Returns nothing.
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*
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* XXX Assumes previously marked scan position belongs to current tid
|
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* ----------------------------------------------------------------
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*/
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void
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ExecTidRestrPos(TidScan *node)
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{
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TidScanState *tidstate;
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tidstate = node->tidstate;
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tidstate->tss_TidPtr = tidstate->tss_MarkTidPtr;
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}
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/* ----------------------------------------------------------------
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* ExecInitTidScan
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*
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* Initializes the tid scan's state information, creates
|
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* scan keys, and opens the base and tid relations.
|
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*
|
||||
* Parameters:
|
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* node: TidNode node produced by the planner.
|
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* estate: the execution state initialized in InitPlan.
|
||||
* ----------------------------------------------------------------
|
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*/
|
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bool
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ExecInitTidScan(TidScan *node, EState *estate, Plan *parent)
|
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{
|
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TidScanState *tidstate;
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CommonScanState *scanstate;
|
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ItemPointer *tidList;
|
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int numTids;
|
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int tidPtr;
|
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List *rangeTable;
|
||||
RangeTblEntry *rtentry;
|
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Oid relid;
|
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Oid reloid;
|
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|
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Relation currentRelation;
|
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int baseid;
|
||||
|
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List *execParam = NULL;
|
||||
|
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/* ----------------
|
||||
* assign execution state to node
|
||||
* ----------------
|
||||
*/
|
||||
node->scan.plan.state = estate;
|
||||
|
||||
/* --------------------------------
|
||||
* Part 1) initialize scan state
|
||||
*
|
||||
* create new CommonScanState for node
|
||||
* --------------------------------
|
||||
*/
|
||||
scanstate = makeNode(CommonScanState);
|
||||
/*
|
||||
scanstate->ss_ProcOuterFlag = false;
|
||||
scanstate->ss_OldRelId = 0;
|
||||
*/
|
||||
|
||||
node->scan.scanstate = scanstate;
|
||||
|
||||
/* ----------------
|
||||
* assign node's base_id .. we don't use AssignNodeBaseid() because
|
||||
* the increment is done later on after we assign the tid scan's
|
||||
* scanstate. see below.
|
||||
* ----------------
|
||||
*/
|
||||
baseid = estate->es_BaseId;
|
||||
/* scanstate->csstate.cstate.bnode.base_id = baseid; */
|
||||
scanstate->cstate.cs_base_id = baseid;
|
||||
|
||||
/* ----------------
|
||||
* create expression context for node
|
||||
* ----------------
|
||||
*/
|
||||
ExecAssignExprContext(estate, &scanstate->cstate);
|
||||
|
||||
#define TIDSCAN_NSLOTS 3
|
||||
/* ----------------
|
||||
* tuple table initialization
|
||||
* ----------------
|
||||
*/
|
||||
ExecInitResultTupleSlot(estate, &scanstate->cstate);
|
||||
ExecInitScanTupleSlot(estate, scanstate);
|
||||
/* ExecInitRawTupleSlot(estate, scanstate); */
|
||||
|
||||
/* ----------------
|
||||
* initialize projection info. result type comes from scan desc
|
||||
* below..
|
||||
* ----------------
|
||||
*/
|
||||
ExecAssignProjectionInfo((Plan *) node, &scanstate->cstate);
|
||||
|
||||
/* --------------------------------
|
||||
* Part 2) initialize tid scan state
|
||||
*
|
||||
* create new TidScanState for node
|
||||
* --------------------------------
|
||||
*/
|
||||
tidstate = makeNode(TidScanState);
|
||||
node->tidstate = tidstate;
|
||||
|
||||
/* ----------------
|
||||
* assign base id to tid scan state also
|
||||
* ----------------
|
||||
*/
|
||||
tidstate->cstate.cs_base_id = baseid;
|
||||
baseid++;
|
||||
estate->es_BaseId = baseid;
|
||||
|
||||
/* ----------------
|
||||
* get the tid node information
|
||||
* ----------------
|
||||
*/
|
||||
tidList = (ItemPointer *)palloc(length(node->tideval) * sizeof(ItemPointer));
|
||||
numTids = 0;
|
||||
if (!node->needRescan)
|
||||
numTids = TidListCreate(node->tideval, scanstate->cstate.cs_ExprContext, tidList);
|
||||
tidPtr = -1;
|
||||
|
||||
CXT1_printf("ExecInitTidScan: context is %d\n", CurrentMemoryContext);
|
||||
|
||||
tidstate->tss_NumTids = numTids;
|
||||
tidstate->tss_TidPtr = tidPtr;
|
||||
tidstate->tss_TidList = tidList;
|
||||
|
||||
/* ----------------
|
||||
* get the range table and direction information
|
||||
* from the execution state (these are needed to
|
||||
* open the relations).
|
||||
* ----------------
|
||||
*/
|
||||
rangeTable = estate->es_range_table;
|
||||
|
||||
/* ----------------
|
||||
* open the base relation
|
||||
* ----------------
|
||||
*/
|
||||
relid = node->scan.scanrelid;
|
||||
rtentry = rt_fetch(relid, rangeTable);
|
||||
reloid = rtentry->relid;
|
||||
|
||||
currentRelation = heap_open(reloid, AccessShareLock);
|
||||
if (currentRelation == NULL)
|
||||
elog(ERROR, "ExecInitTidScan heap_open failed.");
|
||||
scanstate->css_currentRelation = currentRelation;
|
||||
scanstate->css_currentScanDesc = 0;
|
||||
|
||||
/* ----------------
|
||||
* get the scan type from the relation descriptor.
|
||||
* ----------------
|
||||
*/
|
||||
ExecAssignScanType(scanstate, RelationGetDescr(currentRelation));
|
||||
ExecAssignResultTypeFromTL((Plan *) node, &scanstate->cstate);
|
||||
|
||||
/* ----------------
|
||||
* tid scans don't have subtrees..
|
||||
* ----------------
|
||||
*/
|
||||
/* scanstate->ss_ProcOuterFlag = false; */
|
||||
|
||||
tidstate->cstate.cs_TupFromTlist = false;
|
||||
|
||||
/*
|
||||
* if there are some PARAM_EXEC in skankeys then force tid rescan on
|
||||
* first scan.
|
||||
*/
|
||||
((Plan *) node)->chgParam = execParam;
|
||||
|
||||
/* ----------------
|
||||
* all done.
|
||||
* ----------------
|
||||
*/
|
||||
return TRUE;
|
||||
}
|
||||
|
||||
int
|
||||
ExecCountSlotsTidScan(TidScan *node)
|
||||
{
|
||||
return ExecCountSlotsNode(outerPlan((Plan *) node)) +
|
||||
ExecCountSlotsNode(innerPlan((Plan *) node)) + TIDSCAN_NSLOTS;
|
||||
}
|
||||
Reference in New Issue
Block a user