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Allow dynamic allocation of shared memory segments.

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Patch by myself and Amit Kapila.  Design help from Noah Misch.  Review
by Andres Freund.
This commit is contained in:
Robert Haas
2013-10-09 21:05:02 -04:00
parent f566515192
commit 0ac5e5a7e1
18 changed files with 2470 additions and 29 deletions
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26
doc/src/sgml/config.sgml
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@ -1194,6 +1194,32 @@ include 'filename'
</listitem>
</varlistentry>
<varlistentry id="guc-dynamic-shared-memory-type" xreflabel="dynamic_shared_memory_type">
<term><varname>dynamic_shared_memory_type</varname> (<type>enum</type>)</term>
<indexterm>
<primary><varname>dynamic_shared_memory_type</> configuration parameter</primary>
</indexterm>
<listitem>
<para>
Specifies the dynamic shared memory implementation that the server
should use. Possible values are <literal>posix</> (for POSIX shared
memory allocated using <literal>shm_open</>), <literal>sysv</literal>
(for System V shared memory allocated via <literal>shmget</>),
<literal>windows</> (for Windows shared memory), <literal>mmap</>
(to simulate shared memory using memory-mapped files stored in the
data directory), and <literal>none</> (to disable this feature).
Not all values are supported on all platforms; the first supported
option is the default for that platform. The use of the
<literal>mmap</> option, which is not the default on any platform,
is generally discouraged because the operating system may write
modified pages back to disk repeatedly, increasing system I/O load;
however, it may be useful for debugging, when the
<literal>pg_dynshmem</> directory is stored on a RAM disk, or when
other shared memory facilities are not available.
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>