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authorTom Lane <tgl@sss.pgh.pa.us>2002-03-24 17:11:37 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2002-03-24 17:11:37 +0000
commitea10ec1b69c0aba24c1dc4570f40e976a42bfddb (patch)
treebafed68bf8ad65b9d71cc5530ac5d328480a74d0 /doc/src
parent7100cbc1c42f4a20ef14721336b6857b4b489f2f (diff)
downloadpostgresql-ea10ec1b69c0aba24c1dc4570f40e976a42bfddb.tar.gz
postgresql-ea10ec1b69c0aba24c1dc4570f40e976a42bfddb.zip
Tweak labeling of plan qual conditions for more consistency.
Diffstat (limited to 'doc/src')
-rw-r--r--doc/src/sgml/perform.sgml24
-rw-r--r--doc/src/sgml/ref/explain.sgml6
2 files changed, 15 insertions, 15 deletions
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 6b13d6ae3af..17c8a348d0f 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -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>
diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml
index e8ef9fc76f4..46c6c8c955b 100644
--- a/doc/src/sgml/ref/explain.sgml
+++ b/doc/src/sgml/ref/explain.sgml
@@ -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>