Tom Lane wrote:
> It'd clearly be worth our while to mention boosting sort_mem as a
> helpful thing to do during bulk data load --- it should speed up
> btree index creation too. I don't think that tip appears anywhere
> in the docs at the moment.
Added recently, see last sentence:
<term><varname>sort_mem</varname> (<type>integer</type>)</term>
<listitem>
<para>
Specifies the amount of memory to be used by internal sort operations and
hash tables before switching to temporary disk files. The value is
specified in kilobytes, and defaults to 1024 kilobytes (1 MB).
Note that for a complex query, several sort or hash operations might be
running in parallel; each one will be allowed to use as much memory
as this value specifies before it starts to put data into temporary
files. Also, several running sessions could be doing
sort operations simultaneously. So the total memory used could be many
times the value of <varname>sort_mem</varname>. Sort operations are used
by <literal>ORDER BY</>, merge joins, and <command>CREATE INDEX</>.
Hash tables are used in hash joins, hash-based aggregation, and
hash-based processing of <literal>IN</> subqueries. Because
<command>CREATE INDEX</> is used when restoring a database, it might
be good to temporarily increase this value during a restore.
</para>
--
Bruce Momjian | http://candle.pha.pa.us
[EMAIL PROTECTED] | (610) 359-1001
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