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https://git.postgresql.org/git/postgresql.git
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242 lines
4.5 KiB
C
242 lines
4.5 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 1.15 1997/11/25 21:58:53 momjian 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 <string.h>
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#include <postgres.h>
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#include <nodes/plannodes.h>
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#include <tcop/tcopprot.h>
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#include <lib/stringinfo.h>
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#include <commands/explain.h>
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#include <parser/parse_node.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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{
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/* options */
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bool printCost; /* print cost */
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bool 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, bool verbose, CommandDest dest)
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{
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char *s = NULL,
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*s2;
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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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{
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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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es->printCost = true; /* default */
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if (verbose)
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es->printNodes = true;
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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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if (es->printCost)
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{
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s2 = Explain_PlanToString(plan, es);
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if (s == NULL)
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s = s2;
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else
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{
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strcat(s, "\n\n");
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strcat(s, s2);
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}
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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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{
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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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{
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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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{
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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_Group:
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pname = "Group";
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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 = "";
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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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{
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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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{
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RangeTblEntry *rte = nth(((Scan *) plan)->scanrelid - 1, es->rtable);
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sprintf(buf, " on %s", 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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{
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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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{
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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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{
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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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