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343f615e3a
and improperly prevented the main result rel from being closed if it wasn't one of the Append's own result rels. Per report from Hiroshi.
549 lines
15 KiB
C
549 lines
15 KiB
C
/*-------------------------------------------------------------------------
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*
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* nodeAppend.c
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* routines to handle append nodes.
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*
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* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
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* Portions 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/nodeAppend.c,v 1.37 2000/11/09 18:12:53 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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/* INTERFACE ROUTINES
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* ExecInitAppend - initialize the append node
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* ExecProcAppend - retrieve the next tuple from the node
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* ExecEndAppend - shut down the append node
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* ExecReScanAppend - rescan the append node
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*
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* NOTES
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* Each append node contains a list of one or more subplans which
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* must be iteratively processed (forwards or backwards).
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* Tuples are retrieved by executing the 'whichplan'th subplan
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* until the subplan stops returning tuples, at which point that
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* plan is shut down and the next started up.
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*
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* Append nodes don't make use of their left and right
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* subtrees, rather they maintain a list of subplans so
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* a typical append node looks like this in the plan tree:
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*
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* ...
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* /
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* Append -------+------+------+--- nil
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* / \ | | |
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* nil nil ... ... ...
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* subplans
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*
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* Append nodes are currently used for unions, and to support inheritance
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* queries, where several relations need to be scanned.
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* For example, in our standard person/student/employee/student-emp
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* example, where student and employee inherit from person
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* and student-emp inherits from student and employee, the
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* query:
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*
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* retrieve (e.name) from e in person*
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*
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* generates the plan:
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*
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* |
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* Append -------+-------+--------+--------+
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* / \ | | | |
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* nil nil Scan Scan Scan Scan
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* | | | |
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* person employee student student-emp
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*/
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#include "postgres.h"
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#include "access/heapam.h"
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#include "executor/execdebug.h"
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#include "executor/nodeAppend.h"
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#include "parser/parsetree.h"
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static bool exec_append_initialize_next(Append *node);
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/* ----------------------------------------------------------------
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* exec_append_initialize_next
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*
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* Sets up the append node state (i.e. the append state node)
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* for the "next" scan.
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*
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* Returns t iff there is a "next" scan to process.
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* ----------------------------------------------------------------
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*/
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static bool
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exec_append_initialize_next(Append *node)
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{
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EState *estate;
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AppendState *appendstate;
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TupleTableSlot *result_slot;
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List *rangeTable;
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int whichplan;
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int nplans;
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List *inheritrtable;
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RangeTblEntry *rtentry;
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/* ----------------
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* get information from the append node
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* ----------------
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*/
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estate = node->plan.state;
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appendstate = node->appendstate;
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result_slot = appendstate->cstate.cs_ResultTupleSlot;
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rangeTable = estate->es_range_table;
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whichplan = appendstate->as_whichplan;
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nplans = appendstate->as_nplans;
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inheritrtable = node->inheritrtable;
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if (whichplan < 0)
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{
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/* ----------------
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* if scanning in reverse, we start at
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* the last scan in the list and then
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* proceed back to the first.. in any case
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* we inform ExecProcAppend that we are
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* at the end of the line by returning FALSE
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* ----------------
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*/
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appendstate->as_whichplan = 0;
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return FALSE;
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}
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else if (whichplan >= nplans)
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{
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/* ----------------
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* as above, end the scan if we go beyond
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* the last scan in our list..
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* ----------------
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*/
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appendstate->as_whichplan = nplans - 1;
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return FALSE;
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}
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else
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{
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/* ----------------
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* initialize the scan
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* (and update the range table appropriately)
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*
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* (doesn't this leave the range table hosed for anybody upstream
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* of the Append node??? - jolly )
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* ----------------
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*/
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if (node->inheritrelid > 0)
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{
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rtentry = nth(whichplan, inheritrtable);
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Assert(rtentry != NULL);
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rt_store(node->inheritrelid, rangeTable, rtentry);
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}
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if (appendstate->as_junkFilter_list)
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{
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estate->es_junkFilter = (JunkFilter *) nth(whichplan,
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appendstate->as_junkFilter_list);
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}
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if (appendstate->as_result_relation_info_list)
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{
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estate->es_result_relation_info = (RelationInfo *) nth(whichplan,
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appendstate->as_result_relation_info_list);
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}
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result_slot->ttc_whichplan = whichplan;
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return TRUE;
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}
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}
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/* ----------------------------------------------------------------
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* ExecInitAppend
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*
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* Begins all of the subscans of the append node, storing the
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* scan structures in the 'initialized' vector of the append-state
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* structure.
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*
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* (This is potentially wasteful, since the entire result of the
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* append node may not be scanned, but this way all of the
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* structures get allocated in the executor's top level memory
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* block instead of that of the call to ExecProcAppend.)
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*
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* Returns the scan result of the first scan.
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* ----------------------------------------------------------------
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*/
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bool
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ExecInitAppend(Append *node, EState *estate, Plan *parent)
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{
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AppendState *appendstate;
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int nplans;
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List *inheritrtable;
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List *appendplans;
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bool *initialized;
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int i;
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Plan *initNode;
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List *junkList;
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RelationInfo *es_rri = estate->es_result_relation_info;
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bool inherited_result_rel = false;
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CXT1_printf("ExecInitAppend: context is %d\n", CurrentMemoryContext);
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/* ----------------
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* assign execution state to node and get information
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* for append state
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* ----------------
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*/
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node->plan.state = estate;
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appendplans = node->appendplans;
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nplans = length(appendplans);
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inheritrtable = node->inheritrtable;
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initialized = (bool *) palloc(nplans * sizeof(bool));
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MemSet(initialized, 0, nplans * sizeof(bool));
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/* ----------------
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* create new AppendState for our append node
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* ----------------
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*/
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appendstate = makeNode(AppendState);
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appendstate->as_whichplan = 0;
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appendstate->as_nplans = nplans;
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appendstate->as_initialized = initialized;
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node->appendstate = appendstate;
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/* ----------------
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* Miscellaneous initialization
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*
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* Append plans don't have expression contexts because they
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* never call ExecQual or ExecProject.
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* ----------------
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*/
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#define APPEND_NSLOTS 1
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/* ----------------
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* append nodes still have Result slots, which hold pointers
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* to tuples, so we have to initialize them.
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* ----------------
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*/
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ExecInitResultTupleSlot(estate, &appendstate->cstate);
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/*
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* If the inherits rtentry is the result relation, we have to make a
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* result relation info list for all inheritors so we can update their
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* indices and put the result tuples in the right place etc.
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*
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* e.g. replace p (age = p.age + 1) from p in person*
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*/
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if ((es_rri != (RelationInfo *) NULL) &&
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(node->inheritrelid == es_rri->ri_RangeTableIndex))
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{
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List *resultList = NIL;
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Oid initial_reloid = RelationGetRelid(es_rri->ri_RelationDesc);
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List *rtentryP;
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inherited_result_rel = true;
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foreach(rtentryP, inheritrtable)
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{
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RangeTblEntry *rtentry = lfirst(rtentryP);
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Oid reloid = rtentry->relid;
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RelationInfo *rri;
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/*
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* We must recycle the RelationInfo already opened by InitPlan()
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* for the parent rel, else we will leak the associated relcache
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* refcount.
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*/
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if (reloid == initial_reloid)
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{
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Assert(es_rri != NULL); /* check we didn't use it already */
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rri = es_rri;
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es_rri = NULL;
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}
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else
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{
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rri = makeNode(RelationInfo);
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rri->ri_RangeTableIndex = node->inheritrelid;
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rri->ri_RelationDesc = heap_open(reloid, RowExclusiveLock);
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rri->ri_NumIndices = 0;
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rri->ri_IndexRelationDescs = NULL; /* index descs */
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rri->ri_IndexRelationInfo = NULL; /* index key info */
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/*
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* XXX if the operation is a DELETE then we need not open
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* indices, but how to tell that here?
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*/
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if (rri->ri_RelationDesc->rd_rel->relhasindex)
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ExecOpenIndices(rri);
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}
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/*
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* NB: the as_result_relation_info_list must be in the same
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* order as the rtentry list otherwise update or delete on
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* inheritance hierarchies won't work.
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*/
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resultList = lappend(resultList, rri);
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}
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appendstate->as_result_relation_info_list = resultList;
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/* Check that we recycled InitPlan()'s RelationInfo */
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Assert(es_rri == NULL);
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/* Just for paranoia's sake, clear link until we set it properly */
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estate->es_result_relation_info = NULL;
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}
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/* ----------------
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* call ExecInitNode on each of the plans in our list
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* and save the results into the array "initialized"
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* ----------------
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*/
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junkList = NIL;
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for (i = 0; i < nplans; i++)
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{
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/* ----------------
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* NOTE: we first modify range table in
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* exec_append_initialize_next() and
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* then initialize the subnode,
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* since it may use the range table.
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* ----------------
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*/
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appendstate->as_whichplan = i;
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exec_append_initialize_next(node);
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initNode = (Plan *) nth(i, appendplans);
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initialized[i] = ExecInitNode(initNode, estate, (Plan *) node);
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/* ---------------
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* Each targetlist in the subplan may need its own junk filter
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*
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* This is true only when the reln being replaced/deleted is
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* the one that we're looking at the subclasses of
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* ---------------
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*/
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if (inherited_result_rel)
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{
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JunkFilter *j = ExecInitJunkFilter(initNode->targetlist,
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ExecGetTupType(initNode));
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junkList = lappend(junkList, j);
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}
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}
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appendstate->as_junkFilter_list = junkList;
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if (junkList != NIL)
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estate->es_junkFilter = (JunkFilter *) lfirst(junkList);
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/* ----------------
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* initialize the return type from the appropriate subplan.
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* ----------------
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*/
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initNode = (Plan *) nth(0, appendplans);
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ExecAssignResultType(&appendstate->cstate, ExecGetTupType(initNode));
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appendstate->cstate.cs_ProjInfo = NULL;
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/* ----------------
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* return the result from the first subplan's initialization
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* ----------------
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*/
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appendstate->as_whichplan = 0;
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exec_append_initialize_next(node);
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return TRUE;
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}
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int
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ExecCountSlotsAppend(Append *node)
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{
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List *plan;
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List *appendplans = node->appendplans;
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int nSlots = 0;
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foreach(plan, appendplans)
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nSlots += ExecCountSlotsNode((Plan *) lfirst(plan));
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return nSlots + APPEND_NSLOTS;
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}
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/* ----------------------------------------------------------------
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* ExecProcAppend
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*
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* Handles the iteration over the multiple scans.
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*
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* NOTE: Can't call this ExecAppend, that name is used in execMain.
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* ----------------------------------------------------------------
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*/
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TupleTableSlot *
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ExecProcAppend(Append *node)
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{
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EState *estate;
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AppendState *appendstate;
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int whichplan;
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List *appendplans;
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Plan *subnode;
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TupleTableSlot *result;
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TupleTableSlot *result_slot;
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ScanDirection direction;
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/* ----------------
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* get information from the node
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* ----------------
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*/
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appendstate = node->appendstate;
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estate = node->plan.state;
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direction = estate->es_direction;
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appendplans = node->appendplans;
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whichplan = appendstate->as_whichplan;
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result_slot = appendstate->cstate.cs_ResultTupleSlot;
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/* ----------------
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* figure out which subplan we are currently processing
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* ----------------
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*/
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subnode = (Plan *) nth(whichplan, appendplans);
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if (subnode == NULL)
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elog(DEBUG, "ExecProcAppend: subnode is NULL");
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/* ----------------
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* get a tuple from the subplan
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* ----------------
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*/
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result = ExecProcNode(subnode, (Plan *) node);
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if (!TupIsNull(result))
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{
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/* ----------------
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* if the subplan gave us something then place a copy of
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* whatever we get into our result slot and return it.
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*
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* Note we rely on the subplan to retain ownership of the
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* tuple for as long as we need it --- we don't copy it.
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* ----------------
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*/
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return ExecStoreTuple(result->val, result_slot, InvalidBuffer, false);
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}
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else
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{
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/* ----------------
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* .. go on to the "next" subplan in the appropriate
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* direction and try processing again (recursively)
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* ----------------
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*/
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whichplan = appendstate->as_whichplan;
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if (ScanDirectionIsForward(direction))
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appendstate->as_whichplan = whichplan + 1;
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else
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appendstate->as_whichplan = whichplan - 1;
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/* ----------------
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* return something from next node or an empty slot
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* all of our subplans have been exhausted.
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* ----------------
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*/
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if (exec_append_initialize_next(node))
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{
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ExecSetSlotDescriptorIsNew(result_slot, true);
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return ExecProcAppend(node);
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}
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else
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return ExecClearTuple(result_slot);
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}
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}
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/* ----------------------------------------------------------------
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* ExecEndAppend
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*
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* Shuts down the subscans of the append node.
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*
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* Returns nothing of interest.
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* ----------------------------------------------------------------
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*/
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void
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ExecEndAppend(Append *node)
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{
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EState *estate;
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AppendState *appendstate;
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int nplans;
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List *appendplans;
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bool *initialized;
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int i;
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List *resultRelationInfoList;
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/* ----------------
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* get information from the node
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* ----------------
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*/
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appendstate = node->appendstate;
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estate = node->plan.state;
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appendplans = node->appendplans;
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nplans = appendstate->as_nplans;
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initialized = appendstate->as_initialized;
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/* ----------------
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* shut down each of the subscans
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* ----------------
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*/
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for (i = 0; i < nplans; i++)
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{
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if (initialized[i])
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ExecEndNode((Plan *) nth(i, appendplans), (Plan *) node);
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}
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/* ----------------
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* close out the different result relations
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*
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* NB: this must agree with what EndPlan() does to close a result rel
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* ----------------
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*/
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resultRelationInfoList = appendstate->as_result_relation_info_list;
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while (resultRelationInfoList != NIL)
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{
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RelationInfo *resultRelationInfo;
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resultRelationInfo = (RelationInfo *) lfirst(resultRelationInfoList);
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heap_close(resultRelationInfo->ri_RelationDesc, NoLock);
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/* close indices on the result relation, too */
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ExecCloseIndices(resultRelationInfo);
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/*
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* estate may (or may not) be pointing at one of my result relations.
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* If so, make sure EndPlan() doesn't try to close it again!
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*/
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if (estate->es_result_relation_info == resultRelationInfo)
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estate->es_result_relation_info = NULL;
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pfree(resultRelationInfo);
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resultRelationInfoList = lnext(resultRelationInfoList);
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}
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appendstate->as_result_relation_info_list = NIL;
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/*
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* XXX should free appendstate->as_junkfilter_list here
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*/
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}
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void
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ExecReScanAppend(Append *node, ExprContext *exprCtxt, Plan *parent)
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{
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AppendState *appendstate = node->appendstate;
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int nplans = length(node->appendplans);
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int i;
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for (i = 0; i < nplans; i++)
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{
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Plan *rescanNode;
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appendstate->as_whichplan = i;
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rescanNode = (Plan *) nth(i, node->appendplans);
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if (rescanNode->chgParam == NULL)
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{
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exec_append_initialize_next(node);
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ExecReScan((Plan *) rescanNode, exprCtxt, (Plan *) node);
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}
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}
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appendstate->as_whichplan = 0;
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exec_append_initialize_next(node);
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}
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