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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!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.25. pageinspect — low-level inspection of database pages</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="oldsnapshot.html" title="F.24. old_snapshot — inspect old_snapshot_threshold state" /><link rel="next" href="passwordcheck.html" title="F.26. passwordcheck — verify password strength" /></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.25. pageinspect — low-level inspection of database pages</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="oldsnapshot.html" title="F.24. old_snapshot — inspect old_snapshot_threshold state">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 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="passwordcheck.html" title="F.26. passwordcheck — verify password strength">Next</a></td></tr></table><hr /></div><div class="sect1" id="PAGEINSPECT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.25. pageinspect — low-level inspection of database pages <a href="#PAGEINSPECT" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-GENERAL-FUNCS">F.25.1. General Functions</a></span></dt><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-HEAP-FUNCS">F.25.2. Heap Functions</a></span></dt><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-B-TREE-FUNCS">F.25.3. B-Tree Functions</a></span></dt><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-BRIN-FUNCS">F.25.4. BRIN Functions</a></span></dt><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-GIN-FUNCS">F.25.5. GIN Functions</a></span></dt><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-GIST-FUNCS">F.25.6. GiST Functions</a></span></dt><dt><span class="sect2"><a href="pageinspect.html#PAGEINSPECT-HASH-FUNCS">F.25.7. Hash Functions</a></span></dt></dl></div><a id="id-1.11.7.35.2" class="indexterm"></a><p>3  The <code class="filename">pageinspect</code> module provides functions that allow you to4  inspect the contents of database pages at a low level, which is useful for5  debugging purposes.  All of these functions may be used only by superusers.6 </p><div class="sect2" id="PAGEINSPECT-GENERAL-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.1. General Functions <a href="#PAGEINSPECT-GENERAL-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">7     <code class="function">get_raw_page(relname text, fork text, blkno bigint) returns bytea</code>8     <a id="id-1.11.7.35.4.2.1.1.2" class="indexterm"></a>9    </span></dt><dd><p>10      <code class="function">get_raw_page</code> reads the specified block of the named11      relation and returns a copy as a <code class="type">bytea</code> value.  This allows a12      single time-consistent copy of the block to be obtained.13      <em class="replaceable"><code>fork</code></em> should be <code class="literal">'main'</code> for14      the main data fork, <code class="literal">'fsm'</code> for the15      <a class="link" href="storage-fsm.html" title="73.3. Free Space Map">free space map</a>,16      <code class="literal">'vm'</code> for the17      <a class="link" href="storage-vm.html" title="73.4. Visibility Map">visibility map</a>, or18      <code class="literal">'init'</code> for the initialization fork.19     </p></dd><dt><span class="term">20     <code class="function">get_raw_page(relname text, blkno bigint) returns bytea</code>21    </span></dt><dd><p>22      A shorthand version of <code class="function">get_raw_page</code>, for reading23      from the main fork.  Equivalent to24      <code class="literal">get_raw_page(relname, 'main', blkno)</code>25     </p></dd><dt><span class="term">26     <code class="function">page_header(page bytea) returns record</code>27     <a id="id-1.11.7.35.4.2.3.1.2" class="indexterm"></a>28    </span></dt><dd><p>29      <code class="function">page_header</code> shows fields that are common to all30      <span class="productname">PostgreSQL</span> heap and index pages.31     </p><p>32      A page image obtained with <code class="function">get_raw_page</code> should be33      passed as argument.  For example:34</p><pre class="screen">35test=# SELECT * FROM page_header(get_raw_page('pg_class', 0));36    lsn    | checksum | flags  | lower | upper | special | pagesize | version | prune_xid37-----------+----------+--------+-------+-------+---------+----------+---------+-----------38 0/24A1B50 |        0 |      1 |   232 |   368 |    8192 |     8192 |       4 |         039</pre><p>40      The returned columns correspond to the fields in the41      <code class="structname">PageHeaderData</code> struct.42      See <code class="filename">src/include/storage/bufpage.h</code> for details.43     </p><p>44      The <code class="structfield">checksum</code> field is the checksum stored in45      the page, which might be incorrect if the page is somehow corrupted.  If46      data checksums are not enabled for this instance, then the value stored47      is meaningless.48     </p></dd><dt><span class="term">49     <code class="function">page_checksum(page bytea, blkno bigint) returns smallint</code>50     <a id="id-1.11.7.35.4.2.4.1.2" class="indexterm"></a>51    </span></dt><dd><p>52      <code class="function">page_checksum</code> computes the checksum for the page, as if53      it was located at the given block.54     </p><p>55      A page image obtained with <code class="function">get_raw_page</code> should be56      passed as argument.  For example:57</p><pre class="screen">58test=# SELECT page_checksum(get_raw_page('pg_class', 0), 0);59 page_checksum60---------------61         1344362</pre><p>63      Note that the checksum depends on the block number, so matching block64      numbers should be passed (except when doing esoteric debugging).65     </p><p>66      The checksum computed with this function can be compared with67      the <code class="structfield">checksum</code> result field of the68      function <code class="function">page_header</code>.  If data checksums are69      enabled for this instance, then the two values should be equal.70     </p></dd><dt><span class="term">71     <code class="function">fsm_page_contents(page bytea) returns text</code>72     <a id="id-1.11.7.35.4.2.5.1.2" class="indexterm"></a>73    </span></dt><dd><p>74      <code class="function">fsm_page_contents</code> shows the internal node structure75      of an <acronym class="acronym">FSM</acronym> page.  For example:76</p><pre class="screen">77test=# SELECT fsm_page_contents(get_raw_page('pg_class', 'fsm', 0));78</pre><p>79      The output is a multiline string, with one line per node in the binary80      tree within the page.  Only those nodes that are not zero are printed.81      The so-called "next" pointer, which points to the next slot to be82      returned from the page, is also printed.83     </p><p>84      See <code class="filename">src/backend/storage/freespace/README</code> for more85      information on the structure of an <acronym class="acronym">FSM</acronym> page.86     </p></dd></dl></div></div><div class="sect2" id="PAGEINSPECT-HEAP-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.2. Heap Functions <a href="#PAGEINSPECT-HEAP-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">87     <code class="function">heap_page_items(page bytea) returns setof record</code>88     <a id="id-1.11.7.35.5.2.1.1.2" class="indexterm"></a>89    </span></dt><dd><p>90      <code class="function">heap_page_items</code> shows all line pointers on a heap91      page.  For those line pointers that are in use, tuple headers as well92      as tuple raw data are also shown. All tuples are shown, whether or not93      the tuples were visible to an MVCC snapshot at the time the raw page94      was copied.95     </p><p>96      A heap page image obtained with <code class="function">get_raw_page</code> should97      be passed as argument.  For example:98</p><pre class="screen">99test=# SELECT * FROM heap_page_items(get_raw_page('pg_class', 0));100</pre><p>101      See <code class="filename">src/include/storage/itemid.h</code> and102      <code class="filename">src/include/access/htup_details.h</code> for explanations of the fields103      returned.104     </p><p>105      The <code class="function">heap_tuple_infomask_flags</code> function can be106      used to unpack the flag bits of <code class="structfield">t_infomask</code>107      and <code class="structfield">t_infomask2</code> for heap tuples.108     </p></dd><dt><span class="term">109     <code class="function">tuple_data_split(rel_oid oid, t_data bytea, t_infomask integer, t_infomask2 integer, t_bits text [, do_detoast bool]) returns bytea[]</code>110     <a id="id-1.11.7.35.5.2.2.1.2" class="indexterm"></a>111    </span></dt><dd><p>112      <code class="function">tuple_data_split</code> splits tuple data into attributes113      in the same way as backend internals.114</p><pre class="screen">115test=# SELECT tuple_data_split('pg_class'::regclass, t_data, t_infomask, t_infomask2, t_bits) FROM heap_page_items(get_raw_page('pg_class', 0));116</pre><p>117      This function should be called with the same arguments as the return118      attributes of <code class="function">heap_page_items</code>.119     </p><p>120      If <em class="parameter"><code>do_detoast</code></em> is <code class="literal">true</code>,121      attributes will be detoasted as needed. Default value is122      <code class="literal">false</code>.123     </p></dd><dt><span class="term">124     <code class="function">heap_page_item_attrs(page bytea, rel_oid regclass [, do_detoast bool]) returns setof record</code>125     <a id="id-1.11.7.35.5.2.3.1.2" class="indexterm"></a>126    </span></dt><dd><p>127      <code class="function">heap_page_item_attrs</code> is equivalent to128      <code class="function">heap_page_items</code> except that it returns129      tuple raw data as an array of attributes that can optionally130      be detoasted by <em class="parameter"><code>do_detoast</code></em> which is131      <code class="literal">false</code> by default.132     </p><p>133      A heap page image obtained with <code class="function">get_raw_page</code> should134      be passed as argument.  For example:135</p><pre class="screen">136test=# SELECT * FROM heap_page_item_attrs(get_raw_page('pg_class', 0), 'pg_class'::regclass);137</pre><p>138     </p></dd><dt><span class="term">139     <code class="function">heap_tuple_infomask_flags(t_infomask integer, t_infomask2 integer) returns record</code>140     <a id="id-1.11.7.35.5.2.4.1.2" class="indexterm"></a>141    </span></dt><dd><p>142      <code class="function">heap_tuple_infomask_flags</code> decodes the143      <code class="structfield">t_infomask</code> and144      <code class="structfield">t_infomask2</code> returned by145      <code class="function">heap_page_items</code> into a human-readable146      set of arrays made of flag names, with one column for all147      the flags and one column for combined flags. For example:148</p><pre class="screen">149test=# SELECT t_ctid, raw_flags, combined_flags150         FROM heap_page_items(get_raw_page('pg_class', 0)),151           LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2)152         WHERE t_infomask IS NOT NULL OR t_infomask2 IS NOT NULL;153</pre><p>154      This function should be called with the same arguments as the return155      attributes of <code class="function">heap_page_items</code>.156     </p><p>157      Combined flags are displayed for source-level macros that take into158      account the value of more than one raw bit, such as159      <code class="literal">HEAP_XMIN_FROZEN</code>.160     </p><p>161      See <code class="filename">src/include/access/htup_details.h</code> for162      explanations of the flag names returned.163     </p></dd></dl></div></div><div class="sect2" id="PAGEINSPECT-B-TREE-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.3. B-Tree Functions <a href="#PAGEINSPECT-B-TREE-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">164     <code class="function">bt_metap(relname text) returns record</code>165     <a id="id-1.11.7.35.6.2.1.1.2" class="indexterm"></a>166    </span></dt><dd><p>167      <code class="function">bt_metap</code> returns information about a B-tree168      index's metapage.  For example:169</p><pre class="screen">170test=# SELECT * FROM bt_metap('pg_cast_oid_index');171-[ RECORD 1 ]-------------+-------172magic                     | 340322173version                   | 4174root                      | 1175level                     | 0176fastroot                  | 1177fastlevel                 | 0178last_cleanup_num_delpages | 0179last_cleanup_num_tuples   | 230180allequalimage             | f181</pre><p>182     </p></dd><dt><span class="term">183     <code class="function">bt_page_stats(relname text, blkno bigint) returns record</code>184     <a id="id-1.11.7.35.6.2.2.1.2" class="indexterm"></a>185    </span></dt><dd><p>186      <code class="function">bt_page_stats</code> returns summary information about187      a data page of a B-tree index.  For example:188</p><pre class="screen">189test=# SELECT * FROM bt_page_stats('pg_cast_oid_index', 1);190-[ RECORD 1 ]-+-----191blkno         | 1192type          | l193live_items    | 224194dead_items    | 0195avg_item_size | 16196page_size     | 8192197free_size     | 3668198btpo_prev     | 0199btpo_next     | 0200btpo_level    | 0201btpo_flags    | 3202</pre><p>203     </p></dd><dt><span class="term">204     <code class="function">bt_multi_page_stats(relname text, blkno bigint, blk_count bigint) returns setof record</code>205     <a id="id-1.11.7.35.6.2.3.1.2" class="indexterm"></a>206    </span></dt><dd><p>207      <code class="function">bt_multi_page_stats</code> returns the same information208      as <code class="function">bt_page_stats</code>, but does so for each page of the209      range of pages beginning at <em class="parameter"><code>blkno</code></em> and extending210      for <em class="parameter"><code>blk_count</code></em> pages.211      If <em class="parameter"><code>blk_count</code></em> is negative, all pages212      from <em class="parameter"><code>blkno</code></em> to the end of the index are reported213      on.  For example:214</p><pre class="screen">215test=# SELECT * FROM bt_multi_page_stats('pg_proc_oid_index', 5, 2);216-[ RECORD 1 ]-+-----217blkno         | 5218type          | l219live_items    | 367220dead_items    | 0221avg_item_size | 16222page_size     | 8192223free_size     | 808224btpo_prev     | 4225btpo_next     | 6226btpo_level    | 0227btpo_flags    | 1228-[ RECORD 2 ]-+-----229blkno         | 6230type          | l231live_items    | 367232dead_items    | 0233avg_item_size | 16234page_size     | 8192235free_size     | 808236btpo_prev     | 5237btpo_next     | 7238btpo_level    | 0239btpo_flags    | 1240</pre><p>241     </p></dd><dt><span class="term">242     <code class="function">bt_page_items(relname text, blkno bigint) returns setof record</code>243     <a id="id-1.11.7.35.6.2.4.1.2" class="indexterm"></a>244    </span></dt><dd><p>245      <code class="function">bt_page_items</code> returns detailed information about246      all of the items on a B-tree index page.  For example:247</p><pre class="screen">248test=# SELECT itemoffset, ctid, itemlen, nulls, vars, data, dead, htid, tids[0:2] AS some_tids249        FROM bt_page_items('tenk2_hundred', 5);250 itemoffset |   ctid    | itemlen | nulls | vars |          data           | dead |  htid  |      some_tids251------------+-----------+---------+-------+------+-------------------------+------+--------+---------------------252          1 | (16,1)    |      16 | f     | f    | 30 00 00 00 00 00 00 00 |      |        |253          2 | (16,8292) |     616 | f     | f    | 24 00 00 00 00 00 00 00 | f    | (1,6)  | {"(1,6)","(10,22)"}254          3 | (16,8292) |     616 | f     | f    | 25 00 00 00 00 00 00 00 | f    | (1,18) | {"(1,18)","(4,22)"}255          4 | (16,8292) |     616 | f     | f    | 26 00 00 00 00 00 00 00 | f    | (4,18) | {"(4,18)","(6,17)"}256          5 | (16,8292) |     616 | f     | f    | 27 00 00 00 00 00 00 00 | f    | (1,2)  | {"(1,2)","(1,19)"}257          6 | (16,8292) |     616 | f     | f    | 28 00 00 00 00 00 00 00 | f    | (2,24) | {"(2,24)","(4,11)"}258          7 | (16,8292) |     616 | f     | f    | 29 00 00 00 00 00 00 00 | f    | (2,17) | {"(2,17)","(11,2)"}259          8 | (16,8292) |     616 | f     | f    | 2a 00 00 00 00 00 00 00 | f    | (0,25) | {"(0,25)","(3,20)"}260          9 | (16,8292) |     616 | f     | f    | 2b 00 00 00 00 00 00 00 | f    | (0,10) | {"(0,10)","(0,14)"}261         10 | (16,8292) |     616 | f     | f    | 2c 00 00 00 00 00 00 00 | f    | (1,3)  | {"(1,3)","(3,9)"}262         11 | (16,8292) |     616 | f     | f    | 2d 00 00 00 00 00 00 00 | f    | (6,28) | {"(6,28)","(11,1)"}263         12 | (16,8292) |     616 | f     | f    | 2e 00 00 00 00 00 00 00 | f    | (0,27) | {"(0,27)","(1,13)"}264         13 | (16,8292) |     616 | f     | f    | 2f 00 00 00 00 00 00 00 | f    | (4,17) | {"(4,17)","(4,21)"}265(13 rows)266</pre><p>267      This is a B-tree leaf page.  All tuples that point to the table268      happen to be posting list tuples (all of which store a total of269      100 6 byte TIDs).  There is also a <span class="quote">“<span class="quote">high key</span>”</span> tuple270      at <code class="literal">itemoffset</code> number 1.271      <code class="structfield">ctid</code> is used to store encoded272      information about each tuple in this example, though leaf page273      tuples often store a heap TID directly in the274      <code class="structfield">ctid</code> field instead.275      <code class="structfield">tids</code> is the list of TIDs stored as a276      posting list.277     </p><p>278      In an internal page (not shown), the block number part of279      <code class="structfield">ctid</code> is a <span class="quote">“<span class="quote">downlink</span>”</span>,280      which is a block number of another page in the index itself.281      The offset part (the second number) of282      <code class="structfield">ctid</code> stores encoded information about283      the tuple, such as the number of columns present (suffix284      truncation may have removed unneeded suffix columns).  Truncated285      columns are treated as having the value <span class="quote">“<span class="quote">minus286       infinity</span>”</span>.287     </p><p>288      <code class="structfield">htid</code> shows a heap TID for the tuple,289      regardless of the underlying tuple representation.  This value290      may match <code class="structfield">ctid</code>, or may be decoded291      from the alternative representations used by posting list tuples292      and tuples from internal pages.  Tuples in internal pages293      usually have the implementation level heap TID column truncated294      away, which is represented as a NULL295      <code class="structfield">htid</code> value.296     </p><p>297      Note that the first item on any non-rightmost page (any page with298      a non-zero value in the <code class="structfield">btpo_next</code> field) is the299      page's <span class="quote">“<span class="quote">high key</span>”</span>, meaning its <code class="structfield">data</code>300      serves as an upper bound on all items appearing on the page, while301      its <code class="structfield">ctid</code> field does not point to302      another block.  Also, on internal pages, the first real data303      item (the first item that is not a high key) reliably has every304      column truncated away, leaving no actual value in its305      <code class="structfield">data</code> field.  Such an item does have a306      valid downlink in its <code class="structfield">ctid</code> field,307      however.308     </p><p>309      For more details about the structure of B-tree indexes, see310      <a class="xref" href="btree-implementation.html#BTREE-STRUCTURE" title="67.4.1. B-Tree Structure">Section 67.4.1</a>.  For more details about311      deduplication and posting lists, see <a class="xref" href="btree-implementation.html#BTREE-DEDUPLICATION" title="67.4.3. Deduplication">Section 67.4.3</a>.312     </p></dd><dt><span class="term">313     <code class="function">bt_page_items(page bytea) returns setof record</code>314     <a id="id-1.11.7.35.6.2.5.1.2" class="indexterm"></a>315    </span></dt><dd><p>316      It is also possible to pass a page to <code class="function">bt_page_items</code>317      as a <code class="type">bytea</code> value.  A page image obtained318      with <code class="function">get_raw_page</code> should be passed as argument.  So319      the last example could also be rewritten like this:320</p><pre class="screen">321test=# SELECT itemoffset, ctid, itemlen, nulls, vars, data, dead, htid, tids[0:2] AS some_tids322        FROM bt_page_items(get_raw_page('tenk2_hundred', 5));323 itemoffset |   ctid    | itemlen | nulls | vars |          data           | dead |  htid  |      some_tids324------------+-----------+---------+-------+------+-------------------------+------+--------+---------------------325          1 | (16,1)    |      16 | f     | f    | 30 00 00 00 00 00 00 00 |      |        |326          2 | (16,8292) |     616 | f     | f    | 24 00 00 00 00 00 00 00 | f    | (1,6)  | {"(1,6)","(10,22)"}327          3 | (16,8292) |     616 | f     | f    | 25 00 00 00 00 00 00 00 | f    | (1,18) | {"(1,18)","(4,22)"}328          4 | (16,8292) |     616 | f     | f    | 26 00 00 00 00 00 00 00 | f    | (4,18) | {"(4,18)","(6,17)"}329          5 | (16,8292) |     616 | f     | f    | 27 00 00 00 00 00 00 00 | f    | (1,2)  | {"(1,2)","(1,19)"}330          6 | (16,8292) |     616 | f     | f    | 28 00 00 00 00 00 00 00 | f    | (2,24) | {"(2,24)","(4,11)"}331          7 | (16,8292) |     616 | f     | f    | 29 00 00 00 00 00 00 00 | f    | (2,17) | {"(2,17)","(11,2)"}332          8 | (16,8292) |     616 | f     | f    | 2a 00 00 00 00 00 00 00 | f    | (0,25) | {"(0,25)","(3,20)"}333          9 | (16,8292) |     616 | f     | f    | 2b 00 00 00 00 00 00 00 | f    | (0,10) | {"(0,10)","(0,14)"}334         10 | (16,8292) |     616 | f     | f    | 2c 00 00 00 00 00 00 00 | f    | (1,3)  | {"(1,3)","(3,9)"}335         11 | (16,8292) |     616 | f     | f    | 2d 00 00 00 00 00 00 00 | f    | (6,28) | {"(6,28)","(11,1)"}336         12 | (16,8292) |     616 | f     | f    | 2e 00 00 00 00 00 00 00 | f    | (0,27) | {"(0,27)","(1,13)"}337         13 | (16,8292) |     616 | f     | f    | 2f 00 00 00 00 00 00 00 | f    | (4,17) | {"(4,17)","(4,21)"}338(13 rows)339</pre><p>340      All the other details are the same as explained in the previous item.341     </p></dd></dl></div></div><div class="sect2" id="PAGEINSPECT-BRIN-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.4. BRIN Functions <a href="#PAGEINSPECT-BRIN-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">342     <code class="function">brin_page_type(page bytea) returns text</code>343     <a id="id-1.11.7.35.7.2.1.1.2" class="indexterm"></a>344    </span></dt><dd><p>345      <code class="function">brin_page_type</code> returns the page type of the given346      <acronym class="acronym">BRIN</acronym> index page, or throws an error if the page is347      not a valid <acronym class="acronym">BRIN</acronym> page.  For example:348</p><pre class="screen">349test=# SELECT brin_page_type(get_raw_page('brinidx', 0));350 brin_page_type351----------------352 meta353</pre><p>354     </p></dd><dt><span class="term">355     <code class="function">brin_metapage_info(page bytea) returns record</code>356     <a id="id-1.11.7.35.7.2.2.1.2" class="indexterm"></a>357    </span></dt><dd><p>358      <code class="function">brin_metapage_info</code> returns assorted information359      about a <acronym class="acronym">BRIN</acronym> index metapage.  For example:360</p><pre class="screen">361test=# SELECT * FROM brin_metapage_info(get_raw_page('brinidx', 0));362   magic    | version | pagesperrange | lastrevmappage363------------+---------+---------------+----------------364 0xA8109CFA |       1 |             4 |              2365</pre><p>366     </p></dd><dt><span class="term">367     <code class="function">brin_revmap_data(page bytea) returns setof tid</code>368     <a id="id-1.11.7.35.7.2.3.1.2" class="indexterm"></a>369    </span></dt><dd><p>370      <code class="function">brin_revmap_data</code> returns the list of tuple371      identifiers in a <acronym class="acronym">BRIN</acronym> index range map page.372      For example:373</p><pre class="screen">374test=# SELECT * FROM brin_revmap_data(get_raw_page('brinidx', 2)) LIMIT 5;375  pages376---------377 (6,137)378 (6,138)379 (6,139)380 (6,140)381 (6,141)382</pre><p>383     </p></dd><dt><span class="term">384     <code class="function">brin_page_items(page bytea, index oid) returns setof record</code>385     <a id="id-1.11.7.35.7.2.4.1.2" class="indexterm"></a>386    </span></dt><dd><p>387      <code class="function">brin_page_items</code> returns the data stored in the388      <acronym class="acronym">BRIN</acronym> data page.  For example:389</p><pre class="screen">390test=# SELECT * FROM brin_page_items(get_raw_page('brinidx', 5),391                                     'brinidx')392       ORDER BY blknum, attnum LIMIT 6;393 itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty |    value394------------+--------+--------+----------+----------+-------------+-------+--------------395        137 |      0 |      1 | t        | f        | f           | f     |396        137 |      0 |      2 | f        | f        | f           | f     | {1 .. 88}397        138 |      4 |      1 | t        | f        | f           | f     |398        138 |      4 |      2 | f        | f        | f           | f     | {89 .. 176}399        139 |      8 |      1 | t        | f        | f           | f     |400        139 |      8 |      2 | f        | f        | f           | f     | {177 .. 264}401</pre><p>402      The returned columns correspond to the fields in the403      <code class="structname">BrinMemTuple</code> and <code class="structname">BrinValues</code> structs.404      See <code class="filename">src/include/access/brin_tuple.h</code> for details.405     </p></dd></dl></div></div><div class="sect2" id="PAGEINSPECT-GIN-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.5. GIN Functions <a href="#PAGEINSPECT-GIN-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">406     <code class="function">gin_metapage_info(page bytea) returns record</code>407     <a id="id-1.11.7.35.8.2.1.1.2" class="indexterm"></a>408    </span></dt><dd><p>409      <code class="function">gin_metapage_info</code> returns information about410      a <acronym class="acronym">GIN</acronym> index metapage.  For example:411</p><pre class="screen">412test=# SELECT * FROM gin_metapage_info(get_raw_page('gin_index', 0));413-[ RECORD 1 ]----+-----------414pending_head     | 4294967295415pending_tail     | 4294967295416tail_free_size   | 0417n_pending_pages  | 0418n_pending_tuples | 0419n_total_pages    | 7420n_entry_pages    | 6421n_data_pages     | 0422n_entries        | 693423version          | 2424</pre><p>425     </p></dd><dt><span class="term">426     <code class="function">gin_page_opaque_info(page bytea) returns record</code>427     <a id="id-1.11.7.35.8.2.2.1.2" class="indexterm"></a>428    </span></dt><dd><p>429      <code class="function">gin_page_opaque_info</code> returns information about430      a <acronym class="acronym">GIN</acronym> index opaque area, like the page type.431      For example:432</p><pre class="screen">433test=# SELECT * FROM gin_page_opaque_info(get_raw_page('gin_index', 2));434 rightlink | maxoff |         flags435-----------+--------+------------------------436         5 |      0 | {data,leaf,compressed}437(1 row)438</pre><p>439     </p></dd><dt><span class="term">440     <code class="function">gin_leafpage_items(page bytea) returns setof record</code>441     <a id="id-1.11.7.35.8.2.3.1.2" class="indexterm"></a>442    </span></dt><dd><p>443      <code class="function">gin_leafpage_items</code> returns information about444      the data stored in a <acronym class="acronym">GIN</acronym> leaf page.  For example:445</p><pre class="screen">446test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids447        FROM gin_leafpage_items(get_raw_page('gin_test_idx', 2));448 first_tid | nbytes |                        some_tids449-----------+--------+----------------------------------------------------------450 (8,41)    |    244 | {"(8,41)","(8,43)","(8,44)","(8,45)","(8,46)"}451 (10,45)   |    248 | {"(10,45)","(10,46)","(10,47)","(10,48)","(10,49)"}452 (12,52)   |    248 | {"(12,52)","(12,53)","(12,54)","(12,55)","(12,56)"}453 (14,59)   |    320 | {"(14,59)","(14,60)","(14,61)","(14,62)","(14,63)"}454 (167,16)  |    376 | {"(167,16)","(167,17)","(167,18)","(167,19)","(167,20)"}455 (170,30)  |    376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}456 (173,44)  |    197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}457(7 rows)458</pre><p>459     </p></dd></dl></div></div><div class="sect2" id="PAGEINSPECT-GIST-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.6. GiST Functions <a href="#PAGEINSPECT-GIST-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">460     <code class="function">gist_page_opaque_info(page bytea) returns record</code>461     <a id="id-1.11.7.35.9.2.1.1.2" class="indexterm"></a>462    </span></dt><dd><p>463      <code class="function">gist_page_opaque_info</code> returns information from464      a <acronym class="acronym">GiST</acronym> index page's opaque area, such as the NSN,465      rightlink and page type.466      For example:467</p><pre class="screen">468test=# SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 2));469 lsn | nsn | rightlink | flags470-----+-----+-----------+--------471 0/1 | 0/0 |         1 | {leaf}472(1 row)473</pre><p>474     </p></dd><dt><span class="term">475     <code class="function">gist_page_items(page bytea, index_oid regclass) returns setof record</code>476     <a id="id-1.11.7.35.9.2.2.1.2" class="indexterm"></a>477    </span></dt><dd><p>478      <code class="function">gist_page_items</code> returns information about479      the data stored in a page of a <acronym class="acronym">GiST</acronym> index.  For example:480</p><pre class="screen">481test=# SELECT * FROM gist_page_items(get_raw_page('test_gist_idx', 0), 'test_gist_idx');482 itemoffset |   ctid    | itemlen | dead |             keys483------------+-----------+---------+------+-------------------------------484          1 | (1,65535) |      40 | f    | (p)=("(185,185),(1,1)")485          2 | (2,65535) |      40 | f    | (p)=("(370,370),(186,186)")486          3 | (3,65535) |      40 | f    | (p)=("(555,555),(371,371)")487          4 | (4,65535) |      40 | f    | (p)=("(740,740),(556,556)")488          5 | (5,65535) |      40 | f    | (p)=("(870,870),(741,741)")489          6 | (6,65535) |      40 | f    | (p)=("(1000,1000),(871,871)")490(6 rows)491</pre><p>492     </p></dd><dt><span class="term">493     <code class="function">gist_page_items_bytea(page bytea) returns setof record</code>494     <a id="id-1.11.7.35.9.2.3.1.2" class="indexterm"></a>495    </span></dt><dd><p>496      Same as <code class="function">gist_page_items</code>, but returns the key data497      as a raw <code class="type">bytea</code> blob.  Since it does not attempt to decode498      the key, it does not need to know which index is involved.  For499      example:500</p><pre class="screen">501test=# SELECT * FROM gist_page_items_bytea(get_raw_page('test_gist_idx', 0));502 itemoffset |   ctid    | itemlen | dead |                                      key_data503------------+-----------+---------+------+-----------------------------------------​-------------------------------------------504          1 | (1,65535) |      40 | f    | \x00000100ffff28000000000000c0644000000000​00c06440000000000000f03f000000000000f03f505          2 | (2,65535) |      40 | f    | \x00000200ffff28000000000000c0744000000000​00c074400000000000e064400000000000e06440506          3 | (3,65535) |      40 | f    | \x00000300ffff28000000000000207f4000000000​00207f400000000000d074400000000000d07440507          4 | (4,65535) |      40 | f    | \x00000400ffff28000000000000c0844000000000​00c084400000000000307f400000000000307f40508          5 | (5,65535) |      40 | f    | \x00000500ffff28000000000000f0894000000000​00f089400000000000c884400000000000c88440509          6 | (6,65535) |      40 | f    | \x00000600ffff28000000000000208f4000000000​00208f400000000000f889400000000000f88940510          7 | (7,65535) |      40 | f    | \x00000700ffff28000000000000408f4000000000​00408f400000000000288f400000000000288f40511(7 rows)512</pre><p>513     </p></dd></dl></div></div><div class="sect2" id="PAGEINSPECT-HASH-FUNCS"><div class="titlepage"><div><div><h3 class="title">F.25.7. Hash Functions <a href="#PAGEINSPECT-HASH-FUNCS" class="id_link">#</a></h3></div></div></div><div class="variablelist"><dl class="variablelist"><dt><span class="term">514     <code class="function">hash_page_type(page bytea) returns text</code>515     <a id="id-1.11.7.35.10.2.1.1.2" class="indexterm"></a>516    </span></dt><dd><p>517      <code class="function">hash_page_type</code> returns page type of518      the given <acronym class="acronym">HASH</acronym> index page.  For example:519</p><pre class="screen">520test=# SELECT hash_page_type(get_raw_page('con_hash_index', 0));521 hash_page_type522----------------523 metapage524</pre><p>525     </p></dd><dt><span class="term">526     <code class="function">hash_page_stats(page bytea) returns setof record</code>527     <a id="id-1.11.7.35.10.2.2.1.2" class="indexterm"></a>528    </span></dt><dd><p>529      <code class="function">hash_page_stats</code> returns information about530      a bucket or overflow page of a <acronym class="acronym">HASH</acronym> index.531      For example:532</p><pre class="screen">533test=# SELECT * FROM hash_page_stats(get_raw_page('con_hash_index', 1));534-[ RECORD 1 ]---+-----------535live_items      | 407536dead_items      | 0537page_size       | 8192538free_size       | 8539hasho_prevblkno | 4096540hasho_nextblkno | 8474541hasho_bucket    | 0542hasho_flag      | 66543hasho_page_id   | 65408544</pre><p>545     </p></dd><dt><span class="term">546     <code class="function">hash_page_items(page bytea) returns setof record</code>547     <a id="id-1.11.7.35.10.2.3.1.2" class="indexterm"></a>548    </span></dt><dd><p>549      <code class="function">hash_page_items</code> returns information about550      the data stored in a bucket or overflow page of a <acronym class="acronym">HASH</acronym>551      index page.  For example:552</p><pre class="screen">553test=# SELECT * FROM hash_page_items(get_raw_page('con_hash_index', 1)) LIMIT 5;554 itemoffset |   ctid    |    data555------------+-----------+------------556          1 | (899,77)  | 1053474816557          2 | (897,29)  | 1053474816558          3 | (894,207) | 1053474816559          4 | (892,159) | 1053474816560          5 | (890,111) | 1053474816561</pre><p>562     </p></dd><dt><span class="term">563     <code class="function">hash_bitmap_info(index oid, blkno bigint) returns record</code>564     <a id="id-1.11.7.35.10.2.4.1.2" class="indexterm"></a>565    </span></dt><dd><p>566      <code class="function">hash_bitmap_info</code> shows the status of a bit567      in the bitmap page for a particular overflow page of <acronym class="acronym">HASH</acronym>568      index. For example:569</p><pre class="screen">570test=# SELECT * FROM hash_bitmap_info('con_hash_index', 2052);571 bitmapblkno | bitmapbit | bitstatus572-------------+-----------+-----------573          65 |         3 | t574</pre><p>575     </p></dd><dt><span class="term">576     <code class="function">hash_metapage_info(page bytea) returns record</code>577     <a id="id-1.11.7.35.10.2.5.1.2" class="indexterm"></a>578    </span></dt><dd><p>579      <code class="function">hash_metapage_info</code> returns information stored580      in the meta page of a <acronym class="acronym">HASH</acronym> index.  For example:581</p><pre class="screen">582test=# SELECT magic, version, ntuples, ffactor, bsize, bmsize, bmshift,583test-#     maxbucket, highmask, lowmask, ovflpoint, firstfree, nmaps, procid,584test-#     regexp_replace(spares::text, '(,0)*}', '}') as spares,585test-#     regexp_replace(mapp::text, '(,0)*}', '}') as mapp586test-# FROM hash_metapage_info(get_raw_page('con_hash_index', 0));587-[ RECORD 1 ]-------------------------------------------------​------------------------------588magic     | 105121344589version   | 4590ntuples   | 500500591ffactor   | 40592bsize     | 8152593bmsize    | 4096594bmshift   | 15595maxbucket | 12512596highmask  | 16383597lowmask   | 8191598ovflpoint | 28599firstfree | 1204600nmaps     | 1601procid    | 450602spares    | {0,0,0,0,0,0,1,1,1,1,1,1,1,1,3,4,4,4,45,55,58,59,​508,567,628,704,1193,1202,1204}603mapp      | {65}604</pre><p>605     </p></dd></dl></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="oldsnapshot.html" title="F.24. old_snapshot — inspect old_snapshot_threshold state">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="passwordcheck.html" title="F.26. passwordcheck — verify password strength">Next</a></td></tr><tr><td width="40%" align="left" valign="top">F.24. old_snapshot — inspect <code class="literal">old_snapshot_threshold</code> state </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> F.26. passwordcheck — verify password strength</td></tr></table></div></body></html>
codekingpro/portable-devtools · Team Ai