rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Tweak labeling of plan qual conditions for more consistency.

This commit is contained in:
Tom Lane 2002-03-24 17:11:37 +00:00
parent 7100cbc1c4
commit ea10ec1b69
3 changed files with 20 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

24
doc/src/sgml/perform.sgml
View File

@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/perform.sgml,v 1.19 2002/03/24 04:31:05 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/perform.sgml,v 1.20 2002/03/24 17:11:37 tgl Exp $
-->
<chapter id="performance-tips">
@ -116,7 +116,7 @@ SELECT * FROM pg_class WHERE relname = 'tenk1';
</para>
<para>
Now let's modify the query to add a qualification clause:
Now let's modify the query to add a WHERE condition:
<programlisting>
regression=# EXPLAIN SELECT * FROM tenk1 WHERE unique1 &lt; 1000;
@ -142,14 +142,14 @@ regression=# EXPLAIN SELECT * FROM tenk1 WHERE unique1 &lt; 1000;
</para>
<para>
Modify the query to restrict the qualification even more:
Modify the query to restrict the condition even more:
<programlisting>
regression=# EXPLAIN SELECT * FROM tenk1 WHERE unique1 &lt; 50;
QUERY PLAN
-------------------------------------------------------------------------------
Index Scan using tenk1_unique1 on tenk1 (cost=0.00..179.33 rows=49 width=148)
Index Filter: (unique1 &lt; 50)
Index Cond: (unique1 &lt; 50)
</programlisting>
and you will see that if we make the WHERE condition selective
@ -161,7 +161,7 @@ regression=# EXPLAIN SELECT * FROM tenk1 WHERE unique1 &lt; 50;
</para>
<para>
Add another condition to the qualification:
Add another clause to the WHERE condition:
<programlisting>
regression=# EXPLAIN SELECT * FROM tenk1 WHERE unique1 &lt; 50 AND
@ -169,7 +169,7 @@ regression-# stringu1 = 'xxx';
QUERY PLAN
-------------------------------------------------------------------------------
Index Scan using tenk1_unique1 on tenk1 (cost=0.00..179.45 rows=1 width=148)
Index Filter: (unique1 &lt; 50)
Index Cond: (unique1 &lt; 50)
Filter: (stringu1 = 'xxx'::name)
</programlisting>
@ -193,10 +193,10 @@ regression-# AND t1.unique2 = t2.unique2;
Nested Loop (cost=0.00..327.02 rows=49 width=296)
-&gt; Index Scan using tenk1_unique1 on tenk1 t1
(cost=0.00..179.33 rows=49 width=148)
Index Filter: (unique1 &lt; 50)
Index Cond: (unique1 &lt; 50)
-&gt; Index Scan using tenk2_unique2 on tenk2 t2
(cost=0.00..3.01 rows=1 width=148)
Index Filter: ("outer".unique2 = t2.unique2)
Index Cond: ("outer".unique2 = t2.unique2)
</programlisting>
</para>
@ -208,7 +208,7 @@ regression-# AND t1.unique2 = t2.unique2;
affect row count of the outer scan. For the inner scan, the unique2 value of the
current
outer-scan tuple is plugged into the inner index scan
to produce an index qualification like
to produce an index condition like
<literal>t2.unique2 = <replaceable>constant</replaceable></literal>. So we get the
same inner-scan plan and costs that we'd get from, say, <literal>explain select
* from tenk2 where unique2 = 42</literal>. The costs of the loop node are then set
@ -246,7 +246,7 @@ regression-# AND t1.unique2 = t2.unique2;
-&gt; Hash (cost=179.33..179.33 rows=49 width=148)
-&gt; Index Scan using tenk1_unique1 on tenk1 t1
(cost=0.00..179.33 rows=49 width=148)
Index Filter: (unique1 &lt; 50)
Index Cond: (unique1 &lt; 50)
</programlisting>
This plan proposes to extract the 50 interesting rows of <classname>tenk1</classname>
@ -279,11 +279,11 @@ regression-# WHERE t1.unique1 &lt; 50 AND t1.unique2 = t2.unique2;
-&gt; Index Scan using tenk1_unique1 on tenk1 t1
(cost=0.00..179.33 rows=49 width=148)
(actual time=0.63..8.91 rows=50 loops=1)
Index Filter: (unique1 &lt; 50)
Index Cond: (unique1 &lt; 50)
-&gt; Index Scan using tenk2_unique2 on tenk2 t2
(cost=0.00..3.01 rows=1 width=148)
(actual time=0.29..0.32 rows=1 loops=50)
Index Filter: ("outer".unique2 = t2.unique2)
Index Cond: ("outer".unique2 = t2.unique2)
Total runtime: 31.60 msec
</screen>

6
doc/src/sgml/ref/explain.sgml
View File

@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/explain.sgml,v 1.18 2002/03/24 16:57:29 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/explain.sgml,v 1.19 2002/03/24 17:11:37 tgl Exp $
PostgreSQL documentation
-->
@ -209,7 +209,7 @@ EXPLAIN SELECT * FROM foo WHERE i = 4;
QUERY PLAN
--------------------------------------------------------------
Index Scan using fi on foo (cost=0.00..5.98 rows=1 width=4)
Index Filter: (i = 4)
Index Cond: (i = 4)
(2 rows)
</computeroutput>
</programlisting>
@ -226,7 +226,7 @@ EXPLAIN SELECT sum(i) FROM foo WHERE i &lt; 10;
---------------------------------------------------------------------
Aggregate (cost=23.93..23.93 rows=1 width=4)
-&gt; Index Scan using fi on foo (cost=0.00..23.92 rows=6 width=4)
Index Filter: (i &lt; 10)
Index Cond: (i &lt; 10)
(3 rows)
</computeroutput>
</programlisting>

10
src/backend/commands/explain.c
View File

@ -5,7 +5,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* $Header: /cvsroot/pgsql/src/backend/commands/explain.c,v 1.74 2002/03/24 04:31:07 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/explain.c,v 1.75 2002/03/24 17:11:36 tgl Exp $
*
*/
@ -389,7 +389,7 @@ explain_outNode(StringInfo str, Plan *plan, Plan *outer_plan,
{
case T_IndexScan:
show_scan_qual(((IndexScan *) plan)->indxqualorig, true,
"Index Filter",
"Index Cond",
((Scan *) plan)->scanrelid,
outer_plan,
str, indent, es);
@ -409,7 +409,7 @@ explain_outNode(StringInfo str, Plan *plan, Plan *outer_plan,
break;
case T_NestLoop:
show_upper_qual(((NestLoop *) plan)->join.joinqual,
"Join Cond",
"Join Filter",
"outer", OUTER, outerPlan(plan),
"inner", INNER, innerPlan(plan),
str, indent, es);
@ -426,7 +426,7 @@ explain_outNode(StringInfo str, Plan *plan, Plan *outer_plan,
"inner", INNER, innerPlan(plan),
str, indent, es);
show_upper_qual(((MergeJoin *) plan)->join.joinqual,
"Join Cond",
"Join Filter",
"outer", OUTER, outerPlan(plan),
"inner", INNER, innerPlan(plan),
str, indent, es);
@ -443,7 +443,7 @@ explain_outNode(StringInfo str, Plan *plan, Plan *outer_plan,
"inner", INNER, innerPlan(plan),
str, indent, es);
show_upper_qual(((HashJoin *) plan)->join.joinqual,
"Join Cond",
"Join Filter",
"outer", OUTER, outerPlan(plan),
"inner", INNER, innerPlan(plan),
str, indent, es);