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Commitdad0e20

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Mention "PostgreSQL"'s hashes as slower/similar to btree.
1 parent1415a83 commitdad0e20

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3 files changed

+23
-19
lines changed

3 files changed

+23
-19
lines changed

‎doc/src/sgml/diskusage.sgml

Lines changed: 11 additions & 9 deletions
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@@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/diskusage.sgml,v 1.1 2002/06/13 05:15:22 momjian Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/diskusage.sgml,v 1.2 2002/06/21 19:06:44 momjian Exp $
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-->
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<chapter id="diskusage">
@@ -22,10 +22,12 @@ $Header: /cvsroot/pgsql/doc/src/sgml/diskusage.sgml,v 1.1 2002/06/13 05:15:22 mo
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</para>
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<para>
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You can monitor disk space from two places; from inside
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<application>psql</> and from the command line using
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<application>contrib/oid2name</>. Using <application>psql</> you can
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issue queries to see the disk usage for any table:
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You can monitor disk space from three places: from
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<application>psql</> using <command>VACUUM</> information, from
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<application>psql</> using <application>contrib/dbsize</>, and from
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the command line using <application>contrib/oid2name</>. Using
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<application>psql</> on a recently vacuumed (or analyzed) database,
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you can issue queries to see the disk usage of any table:
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<programlisting>
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play=# SELECT relfilenode, relpages
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play-# FROM pg_class
@@ -38,10 +40,10 @@ play-# WHERE relname = 'customer';
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</para>
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<para>
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Each page is typically 8 kilobytes. <literal>relpages</> is only
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updated by <command>VACUUM</> and <command>ANALYZE</>. To show the
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space used by <acronym>TOAST</> tables, use a query based on the heap
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relfilenode:
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Each page is typically 8 kilobytes.(Remember,<literal>relpages</>
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is onlyupdated by <command>VACUUM</> and <command>ANALYZE</>.) To
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show thespace used by <acronym>TOAST</> tables, use a query based on
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the heaprelfilenode shown above:
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<programlisting>
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play=# SELECT relname, relpages
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play-# FROM pg_class

‎doc/src/sgml/indices.sgml

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@@ -1,4 +1,4 @@
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/indices.sgml,v 1.33 2002/06/2116:52:00 momjian Exp $ -->
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/indices.sgml,v 1.34 2002/06/2119:06:44 momjian Exp $ -->
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<chapter id="indexes">
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<title id="indexes-title">Indexes</title>
@@ -181,10 +181,11 @@ CREATE INDEX <replaceable>name</replaceable> ON <replaceable>table</replaceable>
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</synopsis>
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<note>
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<para>
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Testing has shown hash indexes to be similar or slower than btree
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indexes, and the index size and build time for hash indexes is much
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worse. Hash indexes also suffer poor performance under high
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concurrency. For these reasons, hash index use is discouraged.
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Testing has shown PostgreSQL's hash indexes to be similar or slower
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than btree indexes, and the index size and build time for hash
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indexes is much worse. Hash indexes also suffer poor performance
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under high concurrency. For these reasons, hash index use is
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discouraged.
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</para>
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</note>
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</para>

‎doc/src/sgml/ref/create_index.sgml

Lines changed: 6 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_index.sgml,v 1.33 2002/06/2116:52:00 momjian Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_index.sgml,v 1.34 2002/06/2119:06:44 momjian Exp $
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PostgreSQL documentation
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-->
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@@ -330,10 +330,11 @@ ERROR: Cannot create index: 'index_name' already exists.
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the <literal>=</literal> operator.
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</para>
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<para>
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Testing has shown hash indexes to be similar or slower than btree
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indexes, and the index size and build time for hash indexes is much
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worse. Hash indexes also suffer poor performance under high
336-
concurrency. For these reasons, hash index use is discouraged.
333+
Testing has shown PostgreSQL's hash indexes to be similar or slower
334+
than btree indexes, and the index size and build time for hash
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indexes is much worse. Hash indexes also suffer poor performance
336+
under high concurrency. For these reasons, hash index use is
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discouraged.
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</para>
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<para>

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