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   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. pg_buffercache — inspect PostgreSQL buffer cache state</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="passwordcheck.html" title="F.24. passwordcheck — verify password strength" /><link rel="next" href="pgcrypto.html" title="F.26. pgcrypto — cryptographic functions" /></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. pg_buffercache — inspect <span class="productname">PostgreSQL</span>
   3     buffer cache state</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="passwordcheck.html" title="F.24. passwordcheck — verify password strength">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 18.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="pgcrypto.html" title="F.26. pgcrypto — cryptographic functions">Next</a></td></tr></table><hr /></div><div class="sect1" id="PGBUFFERCACHE"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.25. pg_buffercache — inspect <span class="productname">PostgreSQL</span>
   4     buffer cache state <a href="#PGBUFFERCACHE" class="id_link">#</a></h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-PG-BUFFERCACHE">F.25.1. The <code class="structname">pg_buffercache</code> View</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-PG-BUFFERCACHE-NUMA">F.25.2. The <code class="structname">pg_buffercache_numa</code> View</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-SUMMARY">F.25.3. The <code class="function">pg_buffercache_summary()</code> Function</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-USAGE-COUNTS">F.25.4. The <code class="function">pg_buffercache_usage_counts()</code> Function</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-PG-BUFFERCACHE-EVICT">F.25.5. The <code class="function">pg_buffercache_evict()</code> Function</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-PG-BUFFERCACHE-EVICT-RELATION">F.25.6. The <code class="structname">pg_buffercache_evict_relation()</code> Function</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-PG-BUFFERCACHE-EVICT-ALL">F.25.7. The <code class="structname">pg_buffercache_evict_all()</code> Function</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-SAMPLE-OUTPUT">F.25.8. Sample Output</a></span></dt><dt><span class="sect2"><a href="pgbuffercache.html#PGBUFFERCACHE-AUTHORS">F.25.9. Authors</a></span></dt></dl></div><a id="id-1.11.7.35.2" class="indexterm"></a><p>
   5   The <code class="filename">pg_buffercache</code> module provides a means for
   6   examining what's happening in the shared buffer cache in real time.
   7   It also offers a low-level way to evict data from it, for testing
   8   purposes.
   9  </p><a id="id-1.11.7.35.4" class="indexterm"></a><a id="id-1.11.7.35.5" class="indexterm"></a><a id="id-1.11.7.35.6" class="indexterm"></a><a id="id-1.11.7.35.7" class="indexterm"></a><a id="id-1.11.7.35.8" class="indexterm"></a><a id="id-1.11.7.35.9" class="indexterm"></a><a id="id-1.11.7.35.10" class="indexterm"></a><p>
  10   This module provides the <code class="function">pg_buffercache_pages()</code>
  11   function (wrapped in the <code class="structname">pg_buffercache</code> view), the
  12   <code class="function">pg_buffercache_numa_pages()</code> function (wrapped in the
  13   <code class="structname">pg_buffercache_numa</code> view), the
  14   <code class="function">pg_buffercache_summary()</code> function, the
  15   <code class="function">pg_buffercache_usage_counts()</code> function, the
  16   <code class="function">pg_buffercache_evict()</code> function, the
  17   <code class="function">pg_buffercache_evict_relation()</code> function and the
  18   <code class="function">pg_buffercache_evict_all()</code> function.
  19  </p><p>
  20   The <code class="function">pg_buffercache_pages()</code> function returns a set of
  21   records, each row describing the state of one shared buffer entry. The
  22   <code class="structname">pg_buffercache</code> view wraps the function for
  23   convenient use.
  24  </p><p>
  25   The <code class="function">pg_buffercache_numa_pages()</code> function provides
  26   <acronym class="acronym">NUMA</acronym> node mappings for shared buffer entries. This
  27   information is not part of <code class="function">pg_buffercache_pages()</code>
  28   itself, as it is much slower to retrieve.
  29   The <code class="structname">pg_buffercache_numa</code> view wraps the function for
  30   convenient use.
  31  </p><p>
  32   The <code class="function">pg_buffercache_summary()</code> function returns a single
  33   row summarizing the state of the shared buffer cache.
  34  </p><p>
  35   The <code class="function">pg_buffercache_usage_counts()</code> function returns a set
  36   of records, each row describing the number of buffers with a given usage
  37   count.
  38  </p><p>
  39   By default, use of the above functions is restricted to superusers and roles
  40   with privileges of the <code class="literal">pg_monitor</code> role. Access may be
  41   granted to others using <code class="command">GRANT</code>.
  42  </p><p>
  43   The <code class="function">pg_buffercache_evict()</code> function allows a block to
  44   be evicted from the buffer pool given a buffer identifier.  Use of this
  45   function is restricted to superusers only.
  46  </p><p>
  47   The <code class="function">pg_buffercache_evict_relation()</code> function allows all
  48   unpinned shared buffers in the relation to be evicted from the buffer pool
  49   given a relation identifier.  Use of this function is restricted to
  50   superusers only.
  51  </p><p>
  52   The <code class="function">pg_buffercache_evict_all()</code> function allows all
  53   unpinned shared buffers to be evicted in the buffer pool.  Use of this
  54   function is restricted to superusers only.
  55  </p><div class="sect2" id="PGBUFFERCACHE-PG-BUFFERCACHE"><div class="titlepage"><div><div><h3 class="title">F.25.1. The <code class="structname">pg_buffercache</code> View <a href="#PGBUFFERCACHE-PG-BUFFERCACHE" class="id_link">#</a></h3></div></div></div><p>
  56    The definitions of the columns exposed by the view are shown in <a class="xref" href="pgbuffercache.html#PGBUFFERCACHE-COLUMNS" title="Table F.14. pg_buffercache Columns">Table F.14</a>.
  57   </p><div class="table" id="PGBUFFERCACHE-COLUMNS"><p class="title"><strong>Table F.14. <code class="structname">pg_buffercache</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_buffercache Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
  58        Column Type
  59       </p>
  60       <p>
  61        Description
  62       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
  63        <code class="structfield">bufferid</code> <code class="type">integer</code>
  64       </p>
  65       <p>
  66        ID, in the range 1..<code class="varname">shared_buffers</code>
  67       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  68        <code class="structfield">relfilenode</code> <code class="type">oid</code>
  69        (references <a class="link" href="catalog-pg-class.html" title="52.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">relfilenode</code>)
  70       </p>
  71       <p>
  72        Filenode number of the relation
  73       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  74        <code class="structfield">reltablespace</code> <code class="type">oid</code>
  75        (references <a class="link" href="catalog-pg-tablespace.html" title="52.56. pg_tablespace"><code class="structname">pg_tablespace</code></a>.<code class="structfield">oid</code>)
  76       </p>
  77       <p>
  78        Tablespace OID of the relation
  79       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  80        <code class="structfield">reldatabase</code> <code class="type">oid</code>
  81        (references <a class="link" href="catalog-pg-database.html" title="52.15. pg_database"><code class="structname">pg_database</code></a>.<code class="structfield">oid</code>)
  82       </p>
  83       <p>
  84        Database OID of the relation
  85       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  86        <code class="structfield">relforknumber</code> <code class="type">smallint</code>
  87       </p>
  88       <p>
  89        Fork number within the relation;  see
  90        <code class="filename">common/relpath.h</code>
  91       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  92        <code class="structfield">relblocknumber</code> <code class="type">bigint</code>
  93       </p>
  94       <p>
  95        Page number within the relation
  96       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  97        <code class="structfield">isdirty</code> <code class="type">boolean</code>
  98       </p>
  99       <p>
 100        Is the page dirty?
 101       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 102        <code class="structfield">usagecount</code> <code class="type">smallint</code>
 103       </p>
 104       <p>
 105        Clock-sweep access count
 106       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 107        <code class="structfield">pinning_backends</code> <code class="type">integer</code>
 108       </p>
 109       <p>
 110        Number of backends pinning this buffer
 111       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
 112    There is one row for each buffer in the shared cache. Unused buffers are
 113    shown with all fields null except <code class="structfield">bufferid</code>.  Shared system
 114    catalogs are shown as belonging to database zero.
 115   </p><p>
 116    Because the cache is shared by all the databases, there will normally be
 117    pages from relations not belonging to the current database.  This means
 118    that there may not be matching join rows in <code class="structname">pg_class</code> for
 119    some rows, or that there could even be incorrect joins.  If you are
 120    trying to join against <code class="structname">pg_class</code>, it's a good idea to
 121    restrict the join to rows having <code class="structfield">reldatabase</code> equal to
 122    the current database's OID or zero.
 123   </p><p>
 124    Since buffer manager locks are not taken to copy the buffer state data that
 125    the view will display, accessing <code class="structname">pg_buffercache</code> view
 126    has less impact on normal buffer activity but it doesn't provide a consistent
 127    set of results across all buffers.  However, we ensure that the information of
 128    each buffer is self-consistent.
 129   </p></div><div class="sect2" id="PGBUFFERCACHE-PG-BUFFERCACHE-NUMA"><div class="titlepage"><div><div><h3 class="title">F.25.2. The <code class="structname">pg_buffercache_numa</code> View <a href="#PGBUFFERCACHE-PG-BUFFERCACHE-NUMA" class="id_link">#</a></h3></div></div></div><p>
 130    The definitions of the columns exposed by the view are shown in <a class="xref" href="pgbuffercache.html#PGBUFFERCACHE-NUMA-COLUMNS" title="Table F.15. pg_buffercache_numa Columns">Table F.15</a>.
 131   </p><div class="table" id="PGBUFFERCACHE-NUMA-COLUMNS"><p class="title"><strong>Table F.15. <code class="structname">pg_buffercache_numa</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_buffercache_numa Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
 132        Column Type
 133       </p>
 134       <p>
 135        Description
 136       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
 137        <code class="structfield">bufferid</code> <code class="type">integer</code>
 138       </p>
 139       <p>
 140        ID, in the range 1..<code class="varname">shared_buffers</code>
 141       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 142        <code class="structfield">os_page_num</code> <code class="type">bigint</code>
 143       </p>
 144       <p>
 145        number of OS memory page for this buffer
 146       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 147        <code class="structfield">numa_node</code> <code class="type">int</code>
 148       </p>
 149       <p>
 150        ID of <acronym class="acronym">NUMA</acronym> node
 151       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
 152    As <acronym class="acronym">NUMA</acronym> node ID inquiry for each page requires memory pages
 153    to be paged-in, the first execution of this function can take a noticeable
 154    amount of time. In all the cases (first execution or not), retrieving this
 155    information is costly and querying the view at a high frequency is not recommended.
 156   </p><div class="warning"><h3 class="title">Warning</h3><p>
 157       When determining the <acronym class="acronym">NUMA</acronym> node, the view touches
 158       all memory pages for the shared memory segment. This will force
 159       allocation of the shared memory, if it wasn't allocated already,
 160       and the memory may get allocated in a single <acronym class="acronym">NUMA</acronym>
 161       node (depending on system configuration).
 162     </p></div></div><div class="sect2" id="PGBUFFERCACHE-SUMMARY"><div class="titlepage"><div><div><h3 class="title">F.25.3. The <code class="function">pg_buffercache_summary()</code> Function <a href="#PGBUFFERCACHE-SUMMARY" class="id_link">#</a></h3></div></div></div><p>
 163    The definitions of the columns exposed by the function are shown in <a class="xref" href="pgbuffercache.html#PGBUFFERCACHE-SUMMARY-COLUMNS" title="Table F.16. pg_buffercache_summary() Output Columns">Table F.16</a>.
 164   </p><div class="table" id="PGBUFFERCACHE-SUMMARY-COLUMNS"><p class="title"><strong>Table F.16. <code class="function">pg_buffercache_summary()</code> Output Columns</strong></p><div class="table-contents"><table class="table" summary="pg_buffercache_summary() Output Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
 165        Column Type
 166       </p>
 167       <p>
 168        Description
 169       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
 170        <code class="structfield">buffers_used</code> <code class="type">int4</code>
 171       </p>
 172       <p>
 173        Number of used shared buffers
 174       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 175        <code class="structfield">buffers_unused</code> <code class="type">int4</code>
 176       </p>
 177       <p>
 178        Number of unused shared buffers
 179       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 180        <code class="structfield">buffers_dirty</code> <code class="type">int4</code>
 181       </p>
 182       <p>
 183        Number of dirty shared buffers
 184       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 185        <code class="structfield">buffers_pinned</code> <code class="type">int4</code>
 186       </p>
 187       <p>
 188        Number of pinned shared buffers
 189       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 190        <code class="structfield">usagecount_avg</code> <code class="type">float8</code>
 191       </p>
 192       <p>
 193        Average usage count of used shared buffers
 194       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
 195    The <code class="function">pg_buffercache_summary()</code> function returns a
 196    single row summarizing the state of all shared buffers. Similar and more
 197    detailed information is provided by the
 198    <code class="structname">pg_buffercache</code> view, but
 199    <code class="function">pg_buffercache_summary()</code> is significantly cheaper.
 200   </p><p>
 201    Like the <code class="structname">pg_buffercache</code> view,
 202    <code class="function">pg_buffercache_summary()</code> does not acquire buffer
 203    manager locks. Therefore concurrent activity can lead to minor inaccuracies
 204    in the result.
 205   </p></div><div class="sect2" id="PGBUFFERCACHE-USAGE-COUNTS"><div class="titlepage"><div><div><h3 class="title">F.25.4. The <code class="function">pg_buffercache_usage_counts()</code> Function <a href="#PGBUFFERCACHE-USAGE-COUNTS" class="id_link">#</a></h3></div></div></div><p>
 206    The definitions of the columns exposed by the function are shown in
 207    <a class="xref" href="pgbuffercache.html#PGBUFFERCACHE_USAGE_COUNTS-COLUMNS" title="Table F.17. pg_buffercache_usage_counts() Output Columns">Table F.17</a>.
 208   </p><div class="table" id="PGBUFFERCACHE_USAGE_COUNTS-COLUMNS"><p class="title"><strong>Table F.17. <code class="function">pg_buffercache_usage_counts()</code> Output Columns</strong></p><div class="table-contents"><table class="table" summary="pg_buffercache_usage_counts() Output Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">
 209        Column Type
 210       </p>
 211       <p>
 212        Description
 213       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
 214        <code class="structfield">usage_count</code> <code class="type">int4</code>
 215       </p>
 216       <p>
 217        A possible buffer usage count
 218       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 219        <code class="structfield">buffers</code> <code class="type">int4</code>
 220       </p>
 221       <p>
 222        Number of buffers with the usage count
 223       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 224        <code class="structfield">dirty</code> <code class="type">int4</code>
 225       </p>
 226       <p>
 227        Number of dirty buffers with the usage count
 228       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 229        <code class="structfield">pinned</code> <code class="type">int4</code>
 230       </p>
 231       <p>
 232        Number of pinned buffers with the usage count
 233       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
 234    The <code class="function">pg_buffercache_usage_counts()</code> function returns a
 235    set of rows summarizing the states of all shared buffers, aggregated over
 236    the possible usage count values.  Similar and more detailed information is
 237    provided by the <code class="structname">pg_buffercache</code> view, but
 238    <code class="function">pg_buffercache_usage_counts()</code> is significantly cheaper.
 239   </p><p>
 240    Like the <code class="structname">pg_buffercache</code> view,
 241    <code class="function">pg_buffercache_usage_counts()</code> does not acquire buffer
 242    manager locks. Therefore concurrent activity can lead to minor inaccuracies
 243    in the result.
 244   </p></div><div class="sect2" id="PGBUFFERCACHE-PG-BUFFERCACHE-EVICT"><div class="titlepage"><div><div><h3 class="title">F.25.5. The <code class="function">pg_buffercache_evict()</code> Function <a href="#PGBUFFERCACHE-PG-BUFFERCACHE-EVICT" class="id_link">#</a></h3></div></div></div><p>
 245    The <code class="function">pg_buffercache_evict()</code> function takes a buffer
 246    identifier, as shown in the <code class="structfield">bufferid</code> column of
 247    the <code class="structname">pg_buffercache</code> view.  It returns information
 248    about whether the buffer was evicted and flushed.  The buffer_evicted
 249    column is true on success, and false if the buffer wasn't valid, if it
 250    couldn't be evicted because it was pinned, or if it became dirty again
 251    after an attempt to write it out.  The buffer_flushed column is true if the
 252    buffer was flushed.  This does not necessarily mean that buffer was flushed
 253    by us, it might be flushed by someone else.  The result is immediately out
 254    of date upon return, as the buffer might become valid again at any time due
 255    to concurrent activity. The function is intended for developer testing
 256    only.
 257   </p></div><div class="sect2" id="PGBUFFERCACHE-PG-BUFFERCACHE-EVICT-RELATION"><div class="titlepage"><div><div><h3 class="title">F.25.6. The <code class="structname">pg_buffercache_evict_relation()</code> Function <a href="#PGBUFFERCACHE-PG-BUFFERCACHE-EVICT-RELATION" class="id_link">#</a></h3></div></div></div><p>
 258    The <code class="function">pg_buffercache_evict_relation()</code> function is very
 259    similar to the <code class="function">pg_buffercache_evict()</code> function.  The
 260    difference is that the <code class="function">pg_buffercache_evict_relation()</code>
 261    takes a relation identifier instead of buffer identifier.  It tries to
 262    evict all buffers for all forks in that relation.
 263
 264    It returns the number of evicted buffers, flushed buffers and the number of
 265    buffers that could not be evicted.  Flushed buffers haven't necessarily
 266    been flushed by us, they might have been flushed by someone else.  The
 267    result is immediately out of date upon return, as buffers might immediately
 268    be read back in due to concurrent activity.  The function is intended for
 269    developer testing only.
 270   </p></div><div class="sect2" id="PGBUFFERCACHE-PG-BUFFERCACHE-EVICT-ALL"><div class="titlepage"><div><div><h3 class="title">F.25.7. The <code class="structname">pg_buffercache_evict_all()</code> Function <a href="#PGBUFFERCACHE-PG-BUFFERCACHE-EVICT-ALL" class="id_link">#</a></h3></div></div></div><p>
 271    The <code class="function">pg_buffercache_evict_all()</code> function is very
 272    similar to the <code class="function">pg_buffercache_evict()</code> function.  The
 273    difference is, the <code class="function">pg_buffercache_evict_all()</code> function
 274    does not take an argument; instead it tries to evict all buffers in the
 275    buffer pool.  It returns the number of evicted buffers, flushed buffers and
 276    the number of buffers that could not be evicted.  Flushed buffers haven't
 277    necessarily been flushed by us, they might have been flushed by someone
 278    else.  The result is immediately out of date upon return, as buffers might
 279    immediately be read back in due to concurrent activity.  The function is
 280    intended for developer testing only.
 281   </p></div><div class="sect2" id="PGBUFFERCACHE-SAMPLE-OUTPUT"><div class="titlepage"><div><div><h3 class="title">F.25.8. Sample Output <a href="#PGBUFFERCACHE-SAMPLE-OUTPUT" class="id_link">#</a></h3></div></div></div><pre class="screen">
 282 regression=# SELECT n.nspname, c.relname, count(*) AS buffers
 283              FROM pg_buffercache b JOIN pg_class c
 284              ON b.relfilenode = pg_relation_filenode(c.oid) AND
 285                 b.reldatabase IN (0, (SELECT oid FROM pg_database
 286                                       WHERE datname = current_database()))
 287              JOIN pg_namespace n ON n.oid = c.relnamespace
 288              GROUP BY n.nspname, c.relname
 289              ORDER BY 3 DESC
 290              LIMIT 10;
 291
 292   nspname   |        relname         | buffers
 293 ------------+------------------------+---------
 294  public     | delete_test_table      |     593
 295  public     | delete_test_table_pkey |     494
 296  pg_catalog | pg_attribute           |     472
 297  public     | quad_poly_tbl          |     353
 298  public     | tenk2                  |     349
 299  public     | tenk1                  |     349
 300  public     | gin_test_idx           |     306
 301  pg_catalog | pg_largeobject         |     206
 302  public     | gin_test_tbl           |     188
 303  public     | spgist_text_tbl        |     182
 304 (10 rows)
 305
 306
 307 regression=# SELECT * FROM pg_buffercache_summary();
 308  buffers_used | buffers_unused | buffers_dirty | buffers_pinned | usagecount_avg
 309 --------------+----------------+---------------+----------------+----------------
 310           248 |        2096904 |            39 |              0 |       3.141129
 311 (1 row)
 312
 313
 314 regression=# SELECT * FROM pg_buffercache_usage_counts();
 315  usage_count | buffers | dirty | pinned
 316 -------------+---------+-------+--------
 317            0 |   14650 |     0 |      0
 318            1 |    1436 |   671 |      0
 319            2 |     102 |    88 |      0
 320            3 |      23 |    21 |      0
 321            4 |       9 |     7 |      0
 322            5 |     164 |   106 |      0
 323 (6 rows)
 324 </pre></div><div class="sect2" id="PGBUFFERCACHE-AUTHORS"><div class="titlepage"><div><div><h3 class="title">F.25.9. Authors <a href="#PGBUFFERCACHE-AUTHORS" class="id_link">#</a></h3></div></div></div><p>
 325    Mark Kirkwood <code class="email">&lt;<a class="email" href="mailto:markir@paradise.net.nz">markir@paradise.net.nz</a>&gt;</code>
 326   </p><p>
 327    Design suggestions: Neil Conway <code class="email">&lt;<a class="email" href="mailto:neilc@samurai.com">neilc@samurai.com</a>&gt;</code>
 328   </p><p>
 329    Debugging advice: Tom Lane <code class="email">&lt;<a class="email" href="mailto:tgl@sss.pgh.pa.us">tgl@sss.pgh.pa.us</a>&gt;</code>
 330   </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="passwordcheck.html" title="F.24. passwordcheck — verify password strength">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="pgcrypto.html" title="F.26. pgcrypto — cryptographic functions">Next</a></td></tr><tr><td width="40%" align="left" valign="top">F.24. passwordcheck — verify password strength </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="40%" align="right" valign="top"> F.26. pgcrypto — cryptographic functions</td></tr></table></div></body></html>