diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/pgbuffercache.sgml | 75 |
1 files changed, 68 insertions, 7 deletions
diff --git a/doc/src/sgml/pgbuffercache.sgml b/doc/src/sgml/pgbuffercache.sgml index b5050cd7343..ef5732942f7 100644 --- a/doc/src/sgml/pgbuffercache.sgml +++ b/doc/src/sgml/pgbuffercache.sgml @@ -27,14 +27,24 @@ <primary>pg_buffercache_evict</primary> </indexterm> + <indexterm> + <primary>pg_buffercache_evict_relation</primary> + </indexterm> + + <indexterm> + <primary>pg_buffercache_evict_all</primary> + </indexterm> + <para> This module provides the <function>pg_buffercache_pages()</function> function (wrapped in the <structname>pg_buffercache</structname> view), <function>pg_buffercache_numa_pages()</function> function (wrapped in the <structname>pg_buffercache_numa</structname> view), the <function>pg_buffercache_summary()</function> function, the - <function>pg_buffercache_usage_counts()</function> function and - the <function>pg_buffercache_evict()</function> function. + <function>pg_buffercache_usage_counts()</function> function, the + <function>pg_buffercache_evict()</function>, the + <function>pg_buffercache_evict_relation()</function> function and the + <function>pg_buffercache_evict_all()</function> function. </para> <para> @@ -76,6 +86,19 @@ function is restricted to superusers only. </para> + <para> + The <function>pg_buffercache_evict_relation()</function> function allows all + unpinned shared buffers in the relation to be evicted from the buffer pool + given a relation identifier. Use of this function is restricted to + superusers only. + </para> + + <para> + The <function>pg_buffercache_evict_all()</function> function allows all + unpinned shared buffers to be evicted in the buffer pool. Use of this + function is restricted to superusers only. + </para> + <sect2 id="pgbuffercache-pg-buffercache"> <title>The <structname>pg_buffercache</structname> View</title> @@ -452,11 +475,49 @@ <para> The <function>pg_buffercache_evict()</function> function takes a buffer identifier, as shown in the <structfield>bufferid</structfield> column of - the <structname>pg_buffercache</structname> view. It returns true on success, - and false if the buffer wasn't valid, if it couldn't be evicted because it - was pinned, or if it became dirty again after an attempt to write it out. - The result is immediately out of date upon return, as the buffer might - become valid again at any time due to concurrent activity. The function is + the <structname>pg_buffercache</structname> view. It returns information + about whether the buffer was evicted and flushed. The buffer_evicted + column is true on success, and false if the buffer wasn't valid, if it + couldn't be evicted because it was pinned, or if it became dirty again + after an attempt to write it out. The buffer_flushed column is true if the + buffer was flushed. This does not necessarily mean that buffer was flushed + by us, it might be flushed by someone else. The result is immediately out + of date upon return, as the buffer might become valid again at any time due + to concurrent activity. The function is intended for developer testing + only. + </para> + </sect2> + + <sect2 id="pgbuffercache-pg-buffercache-evict-relation"> + <title>The <structname>pg_buffercache_evict_relation</structname> Function</title> + <para> + The <function>pg_buffercache_evict_relation()</function> function is very + similar to the <function>pg_buffercache_evict()</function> function. The + difference is that the <function>pg_buffercache_evict_relation()</function> + takes a relation identifier instead of buffer identifier. It tries to + evict all buffers for all forks in that relation. + + It returns the number of evicted buffers, flushed buffers and the number of + buffers that could not be evicted. Flushed buffers haven't necessarily + been flushed by us, they might have been flushed by someone else. The + result is immediately out of date upon return, as buffers might immediately + be read back in due to concurrent activity. The function is intended for + developer testing only. + </para> + </sect2> + + <sect2 id="pgbuffercache-pg-buffercache-evict-all"> + <title>The <structname>pg_buffercache_evict_all</structname> Function</title> + <para> + The <function>pg_buffercache_evict_all()</function> function is very + similar to the <function>pg_buffercache_evict()</function> function. The + difference is, the <function>pg_buffercache_evict_all()</function> function + does not take an argument; instead it tries to evict all buffers in the + buffer pool. It returns the number of evicted buffers, flushed buffers and + the number of buffers that could not be evicted. Flushed buffers haven't + necessarily been flushed by us, they might have been flushed by someone + else. The result is immediately out of date upon return, as buffers might + immediately be read back in due to concurrent activity. The function is intended for developer testing only. </para> </sect2> |