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| author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-13 13:44:03 +0000 |
|---|---|---|
| committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-13 13:44:03 +0000 |
| commit | 293913568e6a7a86fd1479e1cff8e2ecb58d6568 (patch) | |
| tree | fc3b469a3ec5ab71b36ea97cc7aaddb838423a0c /doc/src/sgml/html/pgsurgery.html | |
| parent | Initial commit. (diff) | |
| download | postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.tar.xz postgresql-16-293913568e6a7a86fd1479e1cff8e2ecb58d6568.zip | |
Adding upstream version 16.2.upstream/16.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/src/sgml/html/pgsurgery.html')
| -rw-r--r-- | doc/src/sgml/html/pgsurgery.html | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/doc/src/sgml/html/pgsurgery.html b/doc/src/sgml/html/pgsurgery.html new file mode 100644 index 0000000..1fc89a8 --- /dev/null +++ b/doc/src/sgml/html/pgsurgery.html @@ -0,0 +1,69 @@ +<?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>F.34. pg_surgery — perform low-level surgery on relation data</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="pgstattuple.html" title="F.33. pgstattuple — obtain tuple-level statistics" /><link rel="next" href="pgtrgm.html" title="F.35. pg_trgm — support for similarity of text using trigram matching" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">F.34. pg_surgery — perform low-level surgery on relation data</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="pgstattuple.html" title="F.33. pgstattuple — obtain tuple-level statistics">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="contrib.html" title="Appendix F. Additional Supplied Modules and Extensions">Up</a></td><th width="60%" align="center">Appendix F. Additional Supplied Modules and Extensions</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="pgtrgm.html" title="F.35. pg_trgm — support for similarity of text using trigram matching">Next</a></td></tr></table><hr /></div><div class="sect1" id="PGSURGERY"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.34. pg_surgery — perform low-level surgery on relation data <a href="#PGSURGERY" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="pgsurgery.html#PGSURGERY-FUNCS">F.34.1. Functions</a></span></dt><dt><span class="sect2"><a href="pgsurgery.html#PGSURGERY-AUTHORS">F.34.2. Authors</a></span></dt></dl></div><a id="id-1.11.7.44.2" class="indexterm"></a><p> + The <code class="filename">pg_surgery</code> module provides various functions to + perform surgery on a damaged relation. These functions are unsafe by design + and using them may corrupt (or further corrupt) your database. For example, + these functions can easily be used to make a table inconsistent with its + own indexes, to cause <code class="literal">UNIQUE</code> or + <code class="literal">FOREIGN KEY</code> constraint violations, or even to make + tuples visible which, when read, will cause a database server crash. + They should be used with great caution and only as a last resort. + </p><div class="sect2" id="PGSURGERY-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.34.1. Functions <a href="#PGSURGERY-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term"> + <code class="function">heap_force_kill(regclass, tid[]) returns void</code> + </span></dt><dd><p> + <code class="function">heap_force_kill</code> marks <span class="quote">“<span class="quote">used</span>”</span> line + pointers as <span class="quote">“<span class="quote">dead</span>”</span> without examining the tuples. The + intended use of this function is to forcibly remove tuples that are not + otherwise accessible. For example: +</p><pre class="programlisting"> +test=> select * from t1 where ctid = '(0, 1)'; +ERROR: could not access status of transaction 4007513275 +DETAIL: Could not open file "pg_xact/0EED": No such file or directory. + +test=# select heap_force_kill('t1'::regclass, ARRAY['(0, 1)']::tid[]); + heap_force_kill +----------------- + +(1 row) + +test=# select * from t1 where ctid = '(0, 1)'; +(0 rows) + +</pre><p> + </p></dd><dt><span class="term"> + <code class="function">heap_force_freeze(regclass, tid[]) returns void</code> + </span></dt><dd><p> + <code class="function">heap_force_freeze</code> marks tuples as frozen without + examining the tuple data. The intended use of this function is to + make accessible tuples which are inaccessible due to corrupted + visibility information, or which prevent the table from being + successfully vacuumed due to corrupted visibility information. + For example: +</p><pre class="programlisting"> +test=> vacuum t1; +ERROR: found xmin 507 from before relfrozenxid 515 +CONTEXT: while scanning block 0 of relation "public.t1" + +test=# select ctid from t1 where xmin = 507; + ctid +------- + (0,3) +(1 row) + +test=# select heap_force_freeze('t1'::regclass, ARRAY['(0, 3)']::tid[]); + heap_force_freeze +------------------- + +(1 row) + +test=# select ctid from t1 where xmin = 2; + ctid +------- + (0,3) +(1 row) + +</pre><p> + </p></dd></dl></div></div><div class="sect2" id="PGSURGERY-AUTHORS"><div class="titlepage"><div><div><h3 class="title">F.34.2. Authors <a href="#PGSURGERY-AUTHORS" class="id_link">#</a></h3></div></div></div><p> + Ashutosh Sharma <code class="email"><<a class="email" href="mailto:ashu.coek88@gmail.com">ashu.coek88@gmail.com</a>></code> + </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pgstattuple.html" title="F.33. pgstattuple — obtain tuple-level statistics">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="contrib.html" title="Appendix F. Additional Supplied Modules and Extensions">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="pgtrgm.html" title="F.35. pg_trgm — support for similarity of text using trigram matching">Next</a></td></tr><tr><td width="40%" align="left" valign="top">F.33. pgstattuple — obtain tuple-level statistics </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.2 Documentation">Home</a></td><td width="40%" align="right" valign="top"> F.35. pg_trgm — + support for similarity of text using trigram matching</td></tr></table></div></body></html>
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