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223 lines
4.7 KiB
C
223 lines
4.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* explain.c--
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* Explain the query execution plan
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*
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* Copyright (c) 1994-5, 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/commands/explain.c,v 1.2 1996/10/23 07:40:08 scrappy Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <stdio.h>
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#include "postgres.h"
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#include "parser/catalog_utils.h"
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#include "parser/parse_query.h" /* for MakeTimeRange() */
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#include "nodes/plannodes.h"
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#include "tcop/tcopprot.h"
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#include "utils/elog.h"
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#include "utils/palloc.h"
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#include "lib/stringinfo.h"
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#include "commands/explain.h"
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#include "optimizer/planner.h"
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#include "access/xact.h"
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typedef struct ExplainState {
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/* options */
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int printCost; /* print cost */
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int printNodes; /* do nodeToString() instead */
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/* other states */
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List *rtable; /* range table */
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} ExplainState;
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static char *Explain_PlanToString(Plan *plan, ExplainState *es);
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/*
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* ExplainQuery -
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* print out the execution plan for a given query
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*
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*/
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void
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ExplainQuery(Query *query, List *options, CommandDest dest)
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{
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char *s;
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Plan *plan;
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ExplainState *es;
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int len;
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if (IsAbortedTransactionBlockState()) {
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char *tag = "*ABORT STATE*";
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EndCommand(tag, dest);
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elog(NOTICE, "(transaction aborted): %s",
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"queries ignored until END");
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return;
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}
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/* plan the queries (XXX we've ignored rewrite!!) */
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plan = planner(query);
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/* pg_plan could have failed */
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if (plan == NULL)
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return;
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es = (ExplainState*)malloc(sizeof(ExplainState));
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memset(es, 0, sizeof(ExplainState));
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/* parse options */
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while (options) {
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char *ostr = strVal(lfirst(options));
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if (!strcasecmp(ostr, "cost"))
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es->printCost = 1;
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else if (!strcasecmp(ostr, "full_plan"))
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es->printNodes = 1;
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options = lnext(options);
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}
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es->rtable = query->rtable;
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if (es->printNodes) {
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s = nodeToString(plan);
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} else {
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s = Explain_PlanToString(plan, es);
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}
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/* output the plan */
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len = strlen(s);
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elog(NOTICE, "QUERY PLAN:\n\n%.*s", ELOG_MAXLEN-64, s);
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len -= ELOG_MAXLEN-64;
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while (len > 0) {
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s += ELOG_MAXLEN-64;
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elog(NOTICE, "%.*s", ELOG_MAXLEN-64, s);
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len -= ELOG_MAXLEN-64;
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}
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free(es);
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}
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/*****************************************************************************
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*
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*****************************************************************************/
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/*
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* explain_outNode -
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* converts a Node into ascii string and append it to 'str'
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*/
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static void
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explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
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{
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char *pname;
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char buf[1000];
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int i;
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if (plan==NULL) {
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appendStringInfo(str, "\n");
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return;
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}
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switch(nodeTag(plan)) {
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case T_Result:
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pname = "Result";
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break;
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case T_Append:
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pname = "Append";
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break;
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case T_NestLoop:
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pname = "Nested Loop";
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break;
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case T_MergeJoin:
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pname = "Merge Join";
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break;
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case T_HashJoin:
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pname = "Hash Join";
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break;
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case T_SeqScan:
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pname = "Seq Scan";
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break;
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case T_IndexScan:
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pname = "Index Scan";
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break;
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case T_Temp:
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pname = "Temp Scan";
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break;
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case T_Sort:
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pname = "Sort";
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break;
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case T_Agg:
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pname = "Aggregate";
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break;
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case T_Unique:
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pname = "Unique";
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break;
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case T_Hash:
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pname = "Hash";
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break;
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case T_Tee:
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pname = "Tee";
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break;
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default:
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pname = NULL;
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break;
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}
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for(i=0; i < indent; i++)
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appendStringInfo(str, " ");
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appendStringInfo(str, pname);
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switch(nodeTag(plan)) {
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case T_SeqScan:
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case T_IndexScan:
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if (((Scan*)plan)->scanrelid > 0) {
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RangeTblEntry *rte = nth(((Scan*)plan)->scanrelid-1, es->rtable);
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sprintf(buf, " on %.*s", NAMEDATALEN, rte->refname);
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appendStringInfo(str, buf);
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}
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break;
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default:
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break;
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}
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if (es->printCost) {
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sprintf(buf, " (cost=%.2f size=%d width=%d)",
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plan->cost, plan->plan_size, plan->plan_width);
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appendStringInfo(str, buf);
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}
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appendStringInfo(str, "\n");
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/* lefttree */
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if (outerPlan(plan)) {
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for(i=0; i < indent; i++)
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appendStringInfo(str, " ");
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appendStringInfo(str, " -> ");
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explain_outNode(str, outerPlan(plan), indent+1, es);
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}
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/* righttree */
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if (innerPlan(plan)) {
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for(i=0; i < indent; i++)
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appendStringInfo(str, " ");
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appendStringInfo(str, " -> ");
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explain_outNode(str, innerPlan(plan), indent+1, es);
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}
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return;
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}
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static char *
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Explain_PlanToString(Plan *plan, ExplainState *es)
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{
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StringInfo str;
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char *s;
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if (plan==NULL)
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return "";
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Assert(plan!=NULL);
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str = makeStringInfo();
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explain_outNode(str, plan, 0, es);
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s = str->data;
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pfree(str);
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return s;
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}
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