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Code Issues Releases Wiki Activity

Rename explain's "size" to "rows".

This commit is contained in:
Bruce Momjian 1999-04-23 21:23:49 +00:00
parent 35b168656b
commit fc08814e00
3 changed files with 14 additions and 11 deletions
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4
doc/src/sgml/ref/explain.sgml
View File

@ -102,6 +102,8 @@ Description
<PARA>
This command outputs details about the supplied query.
The default output is the computed query cost.
The cost value is only meaningful to the optimizer in comparing
various query plans.
VERBOSE displays the full query plan and cost to your screen,
and pretty-prints the plan to the postmaster log file.
</para>
@ -135,7 +137,7 @@ To show a query plan for a simple query:
postgres=> explain select * from foo;
NOTICE: QUERY PLAN:
Seq Scan on foo (cost=0.00 size=0 width=4)
Seq Scan on foo (cost=0.00 rows=0 width=4)
EXPLAIN
</ProgramListing>

4
src/backend/commands/explain.c
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@ -4,7 +4,7 @@
*
* Copyright (c) 1994-5, Regents of the University of California
*
* $Id: explain.c,v 1.33 1999/03/23 16:50:46 momjian Exp $
* $Id: explain.c,v 1.34 1999/04/23 21:23:48 momjian Exp $
*
*/
#include <stdio.h>
@ -234,7 +234,7 @@ explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
}
if (es->printCost)
{
appendStringInfo(str, " (cost=%.2f size=%d width=%d)",
appendStringInfo(str, " (cost=%.2f rows=%d width=%d)",
plan->cost, plan->plan_size, plan->plan_width);
}
appendStringInfo(str, "\n");

17
src/man/explain.l
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@ -1,6 +1,6 @@
.\" This is -*-nroff-*-
.\" XXX standard disclaimer belongs here....
.\" $Header: /cvsroot/pgsql/src/man/Attic/explain.l,v 1.10 1998/08/04 15:00:28 momjian Exp $
.\" $Header: /cvsroot/pgsql/src/man/Attic/explain.l,v 1.11 1999/04/23 21:23:49 momjian Exp $
.TH EXPLAIN SQL 06/12/97 PostgreSQL PostgreSQL
.SH NAME
explain - explains statement execution details
@ -10,21 +10,22 @@ explain - explains statement execution details
.fi
.SH DESCRIPTION
This command outputs details about the supplied query. The default
output is the computed query cost. \f2verbose\f1 displays the full query
plan and cost to your screen, and pretty-prints the plan to the postmaster
log file.
output is the computed query cost. The cost value is only meaningful to
the optimizer in comparing various query plans. \f2verbose\f1 displays
the full query plan and cost to your screen, and pretty-prints the plan
to the postmaster log file.
.SH EXAMPLES
In the examples, the table has a single column of float4.
\fBcost\fR is the cost of scanning a base/join relation,
\fBsize\fR is the expected number of tuples from a scan,
\fBrows\fR is the expected number of rows from a scan,
\fBwidth\fR is the length of a tuple.
.nf
tgl=> explain select a from test\g
NOTICE:QUERY PLAN:
Seq Scan on test (cost=0.00 size=0 width=4)
Seq Scan on test (cost=0.00 rows=0 width=4)
EXPLAIN
tgl=> explain verbose select sum(a) from test;
@ -41,8 +42,8 @@ NOTICE:QUERY PLAN:
:expr {VAR :varno 1 :varattno 1 :vartype 700 :varnoold 1 :varoattno 1}})
:qpqual <> :lefttree <> :righttree <> :scanrelid 1} :righttree <> :numagg 1 }
Aggregate (cost=0.00 size=0 width=0)
-> Seq Scan on test (cost=0.00 size=0 width=4)
Aggregate (cost=0.00 rows=0 width=0)
-> Seq Scan on test (cost=0.00 rows=0 width=4)
.fi
The Postgres optimizer has chosen to use a sequential scan to retrieve rows from