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diff --git a/doc/src/sgml/html/disk-usage.html b/doc/src/sgml/html/disk-usage.html new file mode 100644 index 0000000..45fba94 --- /dev/null +++ b/doc/src/sgml/html/disk-usage.html @@ -0,0 +1,83 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>29.1. Determining Disk Usage</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="diskusage.html" title="Chapter 29. Monitoring Disk Usage" /><link rel="next" href="disk-full.html" title="29.2. Disk Full Failure" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">29.1. Determining Disk Usage</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="diskusage.html" title="Chapter 29. Monitoring Disk Usage">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="diskusage.html" title="Chapter 29. Monitoring Disk Usage">Up</a></td><th width="60%" align="center">Chapter 29. Monitoring Disk Usage</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="disk-full.html" title="29.2. Disk Full Failure">Next</a></td></tr></table><hr /></div><div class="sect1" id="DISK-USAGE"><div class="titlepage"><div><div><h2 class="title" style="clear: both">29.1. Determining Disk Usage</h2></div></div></div><a id="id-1.6.16.3.2" class="indexterm"></a><p> + Each table has a primary heap disk file where most of the data is + stored. If the table has any columns with potentially-wide values, + there also might be a <acronym class="acronym">TOAST</acronym> file associated with the table, + which is used to store values too wide to fit comfortably in the main + table (see <a class="xref" href="storage-toast.html" title="73.2. TOAST">Section 73.2</a>). There will be one valid index + on the <acronym class="acronym">TOAST</acronym> table, if present. There also might be indexes + associated with the base table. Each table and index is stored in a + separate disk file — possibly more than one file, if the file would + exceed one gigabyte. Naming conventions for these files are described + in <a class="xref" href="storage-file-layout.html" title="73.1. Database File Layout">Section 73.1</a>. + </p><p> + You can monitor disk space in three ways: + using the SQL functions listed in <a class="xref" href="functions-admin.html#FUNCTIONS-ADMIN-DBSIZE" title="Table 9.94. Database Object Size Functions">Table 9.94</a>, + using the <a class="xref" href="oid2name.html" title="oid2name"><span class="refentrytitle">oid2name</span></a> module, or + using manual inspection of the system catalogs. + The SQL functions are the easiest to use and are generally recommended. + The remainder of this section shows how to do it by inspection of the + system catalogs. + </p><p> + Using <span class="application">psql</span> on a recently vacuumed or analyzed database, + you can issue queries to see the disk usage of any table: +</p><pre class="programlisting"> +SELECT pg_relation_filepath(oid), relpages FROM pg_class WHERE relname = 'customer'; + + pg_relation_filepath | relpages +----------------------+---------- + base/16384/16806 | 60 +(1 row) +</pre><p> + Each page is typically 8 kilobytes. (Remember, <code class="structfield">relpages</code> + is only updated by <code class="command">VACUUM</code>, <code class="command">ANALYZE</code>, and + a few DDL commands such as <code class="command">CREATE INDEX</code>.) The file path name + is of interest if you want to examine the table's disk file directly. + </p><p> + To show the space used by <acronym class="acronym">TOAST</acronym> tables, use a query + like the following: +</p><pre class="programlisting"> +SELECT relname, relpages +FROM pg_class, + (SELECT reltoastrelid + FROM pg_class + WHERE relname = 'customer') AS ss +WHERE oid = ss.reltoastrelid OR + oid = (SELECT indexrelid + FROM pg_index + WHERE indrelid = ss.reltoastrelid) +ORDER BY relname; + + relname | relpages +----------------------+---------- + pg_toast_16806 | 0 + pg_toast_16806_index | 1 +</pre><p> + </p><p> + You can easily display index sizes, too: +</p><pre class="programlisting"> +SELECT c2.relname, c2.relpages +FROM pg_class c, pg_class c2, pg_index i +WHERE c.relname = 'customer' AND + c.oid = i.indrelid AND + c2.oid = i.indexrelid +ORDER BY c2.relname; + + relname | relpages +-------------------+---------- + customer_id_index | 26 +</pre><p> + </p><p> + It is easy to find your largest tables and indexes using this + information: +</p><pre class="programlisting"> +SELECT relname, relpages +FROM pg_class +ORDER BY relpages DESC; + + relname | relpages +----------------------+---------- + bigtable | 3290 + customer | 3144 +</pre><p> + </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="diskusage.html" title="Chapter 29. Monitoring Disk Usage">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="diskusage.html" title="Chapter 29. Monitoring Disk Usage">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="disk-full.html" title="29.2. Disk Full Failure">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 29. Monitoring Disk Usage </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 29.2. Disk Full Failure</td></tr></table></div></body></html>
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