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PostgreSQL/src/backend/commands/explain.c
Tom Lane 1ee26b7764 Reimplement nodeMaterial to use a temporary BufFile (or even memory, if the 
materialized tupleset is small enough) instead of a temporary relation.
This was something I was thinking of doing anyway for performance, and Jan
says he needs it for TOAST because he doesn't want to cope with toasting
noname relations.  With this change, the 'noname table' support in heap.c
is dead code, and I have accordingly removed it.  Also clean up 'noname'
plan handling in planner --- nonames are either sort or materialize plans,
and it seems less confusing to handle them separately under those names.
2000-06-18 22:44:35 +00:00

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/*
* explain.c
* Explain the query execution plan
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/commands/explain.c,v 1.57 2000/06/18 22:43:58 tgl Exp $
*
*/
#include "postgres.h"
#include "commands/explain.h"
#include "lib/stringinfo.h"
#include "nodes/print.h"
#include "optimizer/planner.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteHandler.h"
#include "utils/relcache.h"
typedef struct ExplainState
{
/* options */
bool printCost; /* print cost */
bool printNodes; /* do nodeToString() instead */
/* other states */
List *rtable; /* range table */
} ExplainState;
static char *Explain_PlanToString(Plan *plan, ExplainState *es);
static void ExplainOneQuery(Query *query, bool verbose, CommandDest dest);
/* Convert a null string pointer into "<>" */
#define stringStringInfo(s) (((s) == NULL) ? "<>" : (s))
/*
* ExplainQuery -
* print out the execution plan for a given query
*
*/
void
ExplainQuery(Query *query, bool verbose, CommandDest dest)
{
List *rewritten;
List *l;
/* rewriter and planner may not work in aborted state? */
if (IsAbortedTransactionBlockState())
{
elog(NOTICE, "(transaction aborted): %s",
"queries ignored until END");
return;
}
/* rewriter and planner will not cope with utility statements */
if (query->commandType == CMD_UTILITY)
{
elog(NOTICE, "Utility statements have no plan structure");
return;
}
/* Rewrite through rule system */
rewritten = QueryRewrite(query);
/* In the case of an INSTEAD NOTHING, tell at least that */
if (rewritten == NIL)
{
elog(NOTICE, "Query rewrites to nothing");
return;
}
/* Explain every plan */
foreach(l, rewritten)
ExplainOneQuery(lfirst(l), verbose, dest);
}
/*
* ExplainOneQuery -
* print out the execution plan for one query
*
*/
static void
ExplainOneQuery(Query *query, bool verbose, CommandDest dest)
{
char *s;
Plan *plan;
ExplainState *es;
/* plan the query */
plan = planner(query);
/* pg_plan could have failed */
if (plan == NULL)
return;
es = (ExplainState *) palloc(sizeof(ExplainState));
MemSet(es, 0, sizeof(ExplainState));
es->printCost = true; /* default */
if (verbose)
es->printNodes = true;
es->rtable = query->rtable;
if (es->printNodes)
{
s = nodeToString(plan);
if (s)
{
elog(NOTICE, "QUERY DUMP:\n\n%s", s);
pfree(s);
}
}
if (es->printCost)
{
s = Explain_PlanToString(plan, es);
if (s)
{
elog(NOTICE, "QUERY PLAN:\n\n%s", s);
pfree(s);
}
}
if (es->printNodes)
pprint(plan); /* display in postmaster log file */
pfree(es);
}
/*****************************************************************************
*
*****************************************************************************/
/*
* explain_outNode -
* converts a Node into ascii string and append it to 'str'
*/
static void
explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
{
List *l;
Relation relation;
char *pname;
int i;
if (plan == NULL)
{
appendStringInfo(str, "\n");
return;
}
switch (nodeTag(plan))
{
case T_Result:
pname = "Result";
break;
case T_Append:
pname = "Append";
break;
case T_NestLoop:
pname = "Nested Loop";
break;
case T_MergeJoin:
pname = "Merge Join";
break;
case T_HashJoin:
pname = "Hash Join";
break;
case T_SeqScan:
pname = "Seq Scan";
break;
case T_IndexScan:
pname = "Index Scan";
break;
case T_Material:
pname = "Materialize";
break;
case T_Sort:
pname = "Sort";
break;
case T_Group:
pname = "Group";
break;
case T_Agg:
pname = "Aggregate";
break;
case T_Unique:
pname = "Unique";
break;
case T_Hash:
pname = "Hash";
break;
case T_TidScan:
pname = "Tid Scan";
break;
default:
pname = "???";
break;
}
appendStringInfo(str, pname);
switch (nodeTag(plan))
{
case T_IndexScan:
if (ScanDirectionIsBackward(((IndexScan *) plan)->indxorderdir))
appendStringInfo(str, " Backward");
appendStringInfo(str, " using ");
i = 0;
foreach(l, ((IndexScan *) plan)->indxid)
{
relation = RelationIdGetRelation(lfirsti(l));
Assert(relation);
appendStringInfo(str, "%s%s",
(++i > 1) ? ", " : "",
stringStringInfo(RelationGetRelationName(relation)));
/* drop relcache refcount from RelationIdGetRelation */
RelationDecrementReferenceCount(relation);
}
/* FALL THRU */
case T_SeqScan:
case T_TidScan:
if (((Scan *) plan)->scanrelid > 0)
{
RangeTblEntry *rte = nth(((Scan *) plan)->scanrelid - 1, es->rtable);
appendStringInfo(str, " on %s",
stringStringInfo(rte->relname));
if (rte->ref != NULL)
{
if ((strcmp(rte->ref->relname, rte->relname) != 0)
|| (length(rte->ref->attrs) > 0))
{
appendStringInfo(str, " %s",
stringStringInfo(rte->ref->relname));
if (length(rte->ref->attrs) > 0)
{
List *c;
int firstEntry = true;
appendStringInfo(str, " (");
foreach(c, rte->ref->attrs)
{
if (!firstEntry)
{
appendStringInfo(str, ", ");
firstEntry = false;
}
appendStringInfo(str, "%s", strVal(lfirst(c)));
}
appendStringInfo(str, ")");
}
}
}
}
break;
default:
break;
}
if (es->printCost)
{
appendStringInfo(str, " (cost=%.2f..%.2f rows=%.0f width=%d)",
plan->startup_cost, plan->total_cost,
plan->plan_rows, plan->plan_width);
}
appendStringInfo(str, "\n");
/* initPlan-s */
if (plan->initPlan)
{
List *saved_rtable = es->rtable;
List *lst;
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " InitPlan\n");
foreach(lst, plan->initPlan)
{
es->rtable = ((SubPlan *) lfirst(lst))->rtable;
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " -> ");
explain_outNode(str, ((SubPlan *) lfirst(lst))->plan, indent + 2, es);
}
es->rtable = saved_rtable;
}
/* lefttree */
if (outerPlan(plan))
{
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " -> ");
explain_outNode(str, outerPlan(plan), indent + 3, es);
}
/* righttree */
if (innerPlan(plan))
{
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " -> ");
explain_outNode(str, innerPlan(plan), indent + 3, es);
}
/* subPlan-s */
if (plan->subPlan)
{
List *saved_rtable = es->rtable;
List *lst;
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " SubPlan\n");
foreach(lst, plan->subPlan)
{
es->rtable = ((SubPlan *) lfirst(lst))->rtable;
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " -> ");
explain_outNode(str, ((SubPlan *) lfirst(lst))->plan, indent + 4, es);
}
es->rtable = saved_rtable;
}
if (nodeTag(plan) == T_Append)
{
List *saved_rtable = es->rtable;
List *lst;
int whichplan = 0;
Append *appendplan = (Append *) plan;
foreach(lst, appendplan->appendplans)
{
Plan *subnode = (Plan *) lfirst(lst);
if (appendplan->inheritrelid > 0)
{
RangeTblEntry *rtentry;
rtentry = nth(whichplan, appendplan->inheritrtable);
Assert(rtentry != NULL);
rt_store(appendplan->inheritrelid, es->rtable, rtentry);
}
else
es->rtable = nth(whichplan, appendplan->unionrtables);
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " -> ");
explain_outNode(str, subnode, indent + 4, es);
whichplan++;
}
es->rtable = saved_rtable;
}
}
static char *
Explain_PlanToString(Plan *plan, ExplainState *es)
{
StringInfoData str;
/* see stringinfo.h for an explanation of this maneuver */
initStringInfo(&str);
if (plan != NULL)
explain_outNode(&str, plan, 0, es);
return str.data;
}
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