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Add some code to EXPLAIN to show the targetlist (ie, output columns) 

of each plan node.  For the moment this is debug support only and is
not enabled unless EXPLAIN_PRINT_TLISTS is defined at build time.
Later I'll see about the idea of letting EXPLAIN VERBOSE do it.
This commit is contained in:
Tom Lane 2008-04-17 18:30:18 +00:00
parent d1cbd26ded
commit c5e4e91a96
1 changed files with 57 additions and 2 deletions
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59
src/backend/commands/explain.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.171 2008/03/26 18:48:59 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.172 2008/04/17 18:30:18 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -61,6 +61,8 @@ static void explain_outNode(StringInfo str,
Plan *plan, PlanState *planstate,
Plan *outer_plan,
int indent, ExplainState *es);
static void show_plan_tlist(Plan *plan,
StringInfo str, int indent, ExplainState *es);
static void show_scan_qual(List *qual, const char *qlabel,
int scanrelid, Plan *outer_plan, Plan *inner_plan,
StringInfo str, int indent, ExplainState *es);
@ -443,7 +445,7 @@ explain_outNode(StringInfo str,
Plan *outer_plan,
int indent, ExplainState *es)
{
char *pname;
const char *pname;
int i;
if (plan == NULL)
@ -744,6 +746,9 @@ explain_outNode(StringInfo str,
appendStringInfo(str, " (never executed)");
appendStringInfoChar(str, '\n');
/* target list */
show_plan_tlist(plan, str, indent, es);
/* quals, sort keys, etc */
switch (nodeTag(plan))
{
@ -1043,6 +1048,56 @@ explain_outNode(StringInfo str,
}
}
/*
* Show the targetlist of a plan node
*/
static void
show_plan_tlist(Plan *plan,
StringInfo str, int indent, ExplainState *es)
{
#ifdef EXPLAIN_PRINT_TLISTS
List *context;
bool useprefix;
ListCell *lc;
int i;
/* No work if empty tlist (this occurs eg in bitmap indexscans) */
if (plan->targetlist == NIL)
return;
/* The tlist of an Append isn't real helpful, so suppress it */
if (IsA(plan, Append))
return;
/* Set up deparsing context */
context = deparse_context_for_plan((Node *) outerPlan(plan),
(Node *) innerPlan(plan),
es->rtable);
useprefix = list_length(es->rtable) > 1;
/* Emit line prefix */
for (i = 0; i < indent; i++)
appendStringInfo(str, " ");
appendStringInfo(str, " Output: ");
/* Deparse each non-junk result column */
i = 0;
foreach(lc, plan->targetlist)
{
TargetEntry *tle = (TargetEntry *) lfirst(lc);
if (tle->resjunk)
continue;
if (i++ > 0)
appendStringInfo(str, ", ");
appendStringInfoString(str,
deparse_expression((Node *) tle->expr, context,
useprefix, false));
}
appendStringInfoChar(str, '\n');
#endif /* EXPLAIN_PRINT_TLISTS */
}
/*
* Show a qualifier expression for a scan plan node
*