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Add --sampling-rate option to pgbench.

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This allows logging only some fraction of transactions, greatly reducing
the amount of log generated.

Tomas Vondra, reviewed by Robert Haas and Jeff Janes.
This commit is contained in:
Heikki Linnakangas
2012-10-03 15:37:42 +03:00
parent 7ae1815961
commit e1be1df51f
2 changed files with 67 additions and 11 deletions
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24
doc/src/sgml/pgbench.sgml
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@ -316,6 +316,24 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--sampling-rate</option> <replaceable>rate</></term>
<listitem>
<para>
Sampling rate, used when writing data into the log, to reduce the
amount of log generated. If this option is given, only the specified
fraction of transactions are logged. 1.0 means all transactions will
be logged, 0.05 means only 5% of the transactions will be logged.
</para>
<para>
Remember to take the sampling rate into account when processing the
log file. For example, when computing tps values, you need to multiply
the numbers accordingly (e.g. with 0.01 sample rate, you'll only get
1/100 of the actual tps).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-M</option> <replaceable>querymode</></term>
<listitem>
@ -750,6 +768,12 @@ END;
0 201 2513 0 1175850569 608
0 202 2038 0 1175850569 2663
</screen></para>
<para>
When running a long test on hardware that can handle a lot of transactions,
the log files can become very large. The <option>--sampling-rate</> option
can be used to log only a random sample of transactions.
</para>
</refsect2>
<refsect2>