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Update storage.sgml to describe the 9.0 tablespace directory layout.

This commit is contained in:
Tom Lane 2010-10-19 21:52:59 -04:00
parent 1c72614be7
commit c33bfb8b9b
1 changed files with 16 additions and 6 deletions
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doc/src/sgml/storage.sgml
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@ -174,8 +174,6 @@ adjusted using the configuration option <option>--with-segsize</option>
when building <productname>PostgreSQL</>.)
In principle, free space map and visibility map forks could require multiple
segments as well, though this is unlikely to happen in practice.
The contents of tables and indexes are discussed further in
<xref linkend="storage-page-layout">.
</para>
<para>
@ -187,15 +185,27 @@ its <acronym>TOAST</> table, if any.
See <xref linkend="storage-toast"> for more information.
</para>
<para>
The contents of tables and indexes are discussed further in
<xref linkend="storage-page-layout">.
</para>
<para>
Tablespaces make the scenario more complicated. Each user-defined tablespace
has a symbolic link inside the <varname>PGDATA</><filename>/pg_tblspc</>
directory, which points to the physical tablespace directory (as specified in
its <command>CREATE TABLESPACE</> command). The symbolic link is named after
directory, which points to the physical tablespace directory (i.e., the
location specified in the tablespace's <command>CREATE TABLESPACE</> command).
This symbolic link is named after
the tablespace's OID. Inside the physical tablespace directory there is
a subdirectory with a name that depends on the <productname>PostgreSQL</>
server version, such as <literal>PG_9.0_201008051</>. (The reason for using
this subdirectory is so that successive versions of the database can use
the same <command>CREATE TABLESPACE</> location value without conflicts.)
Within the version-specific subdirectory, there is
a subdirectory for each database that has elements in the tablespace, named
after the database's OID. Tables within that directory follow the filenode
naming scheme. The <literal>pg_default</> tablespace is not accessed through
after the database's OID. Tables and indexes are stored within that
directory, using the filenode naming scheme.
The <literal>pg_default</> tablespace is not accessed through
<filename>pg_tblspc</>, but corresponds to
<varname>PGDATA</><filename>/base</>. Similarly, the <literal>pg_global</>
tablespace is not accessed through <filename>pg_tblspc</>, but corresponds to