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- <!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>7.6. LIMIT and OFFSET</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 V1.79.1" /><link rel="prev" href="queries-order.html" title="7.5. Sorting Rows" /><link rel="next" href="queries-values.html" title="7.7. VALUES Lists" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">7.6. <code xmlns="http://www.w3.org/1999/xhtml" class="literal">LIMIT</code> and <code xmlns="http://www.w3.org/1999/xhtml" class="literal">OFFSET</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="queries-order.html" title="7.5. Sorting Rows">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="queries.html" title="Chapter 7. Queries">Up</a></td><th width="60%" align="center">Chapter 7. Queries</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="queries-values.html" title="7.7. VALUES Lists">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="QUERIES-LIMIT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">7.6. <code class="literal">LIMIT</code> and <code class="literal">OFFSET</code></h2></div></div></div><a id="id-1.5.6.10.2" class="indexterm"></a><a id="id-1.5.6.10.3" class="indexterm"></a><p>
- <code class="literal">LIMIT</code> and <code class="literal">OFFSET</code> allow you to retrieve just
- a portion of the rows that are generated by the rest of the query:
- </p><pre class="synopsis">
- SELECT <em class="replaceable"><code>select_list</code></em>
- FROM <em class="replaceable"><code>table_expression</code></em>
- [<span class="optional"> ORDER BY ... </span>]
- [<span class="optional"> LIMIT { <em class="replaceable"><code>number</code></em> | ALL } </span>] [<span class="optional"> OFFSET <em class="replaceable"><code>number</code></em> </span>]
- </pre><p>
- </p><p>
- If a limit count is given, no more than that many rows will be
- returned (but possibly fewer, if the query itself yields fewer rows).
- <code class="literal">LIMIT ALL</code> is the same as omitting the <code class="literal">LIMIT</code>
- clause, as is <code class="literal">LIMIT</code> with a NULL argument.
- </p><p>
- <code class="literal">OFFSET</code> says to skip that many rows before beginning to
- return rows. <code class="literal">OFFSET 0</code> is the same as omitting the
- <code class="literal">OFFSET</code> clause, as is <code class="literal">OFFSET</code> with a NULL argument.
- </p><p>
- If both <code class="literal">OFFSET</code>
- and <code class="literal">LIMIT</code> appear, then <code class="literal">OFFSET</code> rows are
- skipped before starting to count the <code class="literal">LIMIT</code> rows that
- are returned.
- </p><p>
- When using <code class="literal">LIMIT</code>, it is important to use an
- <code class="literal">ORDER BY</code> clause that constrains the result rows into a
- unique order. Otherwise you will get an unpredictable subset of
- the query's rows. You might be asking for the tenth through
- twentieth rows, but tenth through twentieth in what ordering? The
- ordering is unknown, unless you specified <code class="literal">ORDER BY</code>.
- </p><p>
- The query optimizer takes <code class="literal">LIMIT</code> into account when
- generating query plans, so you are very likely to get different
- plans (yielding different row orders) depending on what you give
- for <code class="literal">LIMIT</code> and <code class="literal">OFFSET</code>. Thus, using
- different <code class="literal">LIMIT</code>/<code class="literal">OFFSET</code> values to select
- different subsets of a query result <span class="emphasis"><em>will give
- inconsistent results</em></span> unless you enforce a predictable
- result ordering with <code class="literal">ORDER BY</code>. This is not a bug; it
- is an inherent consequence of the fact that SQL does not promise to
- deliver the results of a query in any particular order unless
- <code class="literal">ORDER BY</code> is used to constrain the order.
- </p><p>
- The rows skipped by an <code class="literal">OFFSET</code> clause still have to be
- computed inside the server; therefore a large <code class="literal">OFFSET</code>
- might be inefficient.
- </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="queries-order.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="queries.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="queries-values.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">7.5. Sorting Rows </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 7.7. <code class="literal">VALUES</code> Lists</td></tr></table></div></body></html>
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