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Document brin_summarize_new_pages

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Pointer out by Jeff Janes
This commit is contained in:
Alvaro Herrera
2015-12-28 15:28:19 -03:00
parent 54aaafe95f
commit ac443d1034
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20
doc/src/sgml/brin.sgml
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@@ -58,6 +58,26 @@
store more index entries), but at the same time the summary data stored can
be more precise and more data blocks can be skipped during an index scan.
</para>
<sect2 id="brin-operation">
<title>Index Maintenance</title>
<para>
At the time of creation, all existing index pages are scanned and a
summary index tuple is created for each range, including the
possibly-incomplete range at the end.
As new pages are filled with data, page ranges that are already
summarized will cause the summary information to be updated with data
from the new tuples.
When a new page is created that does not fall within the last
summarized range, that range does not automatically acquire a summary
tuple; those tuples remain unsummarized until a summarization run is
invoked later, creating initial summaries.
This process can be invoked manually using the
<function>brin_summarize_new_pages(regclass)</function> function,
or automatically when <command>VACUUM</command> processes the table.
</para>
</sect2>
</sect1>
<sect1 id="brin-builtin-opclasses">

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doc/src/sgml/func.sgml
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@@ -17912,6 +17912,48 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
</sect2>
<sect2 id="functions-admin-index">
<title>Index Maintenance Functions</title>
<indexterm>
<primary>brin_summarize_new_values</primary>
</indexterm>
<para>
<xref linkend="functions-admin-index-table"> shows the functions
available for index maintenance tasks.
</para>
<table id="functions-admin-index-table">
<title>Index Maintenance Functions</title>
<tgroup cols="3">
<thead>
<row><entry>Name</entry> <entry>Return Type</entry> <entry>Description</entry></row>
</thead>
<tbody>
<row>
<entry>
<literal><function>brin_summarize_new_values(<parameter>index_oid</> <type>regclass</>)</function></literal>
</entry>
<entry><type>integer</type></entry>
<entry>summarize page ranges not already summarized</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
<function>brin_summarize_new_values</> receives a BRIN index OID as
argument and inspects the index to find page ranges in the base table
that are not currently summarized by the index; for any such range
it creates a new summary index tuple by scanning the table pages.
It returns the number of new page range summaries that were inserted
into the index.
</para>
</sect2>
<sect2 id="functions-admin-genfile">
<title>Generic File Access Functions</title>