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Correct description of PageHeaderData layout in documentation

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Back-patch to 9.3 where PageHeaderData layout was changed.

Michael Paquier
This commit is contained in:
Fujii Masao 2015-09-11 13:02:15 +09:00
parent 683bfbdb99
commit 5b0317b5af
1 changed files with 13 additions and 13 deletions
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doc/src/sgml/storage.sgml
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@ -758,18 +758,18 @@ data. Empty in ordinary tables.</entry>
<para> <para>
The first 24 bytes of each page consists of a page header The first 24 bytes of each page consists of a page header
(PageHeaderData). Its format is detailed in <xref (<structname>PageHeaderData</>). Its format is detailed in <xref
linkend="pageheaderdata-table">. The first two fields track the most linkend="pageheaderdata-table">. The first field tracks the most
recent WAL entry related to this page. Next is a 2-byte field recent WAL entry related to this page. The second field contains
containing flag bits. This is followed by three 2-byte integer fields the page checksum if <xref linkend="app-initdb-data-checksums"> are
(<structfield>pd_lower</structfield>, <structfield>pd_upper</structfield>, enabled. Next is a 2-byte field containing flag bits. This is followed
and <structfield>pd_special</structfield>). These contain byte offsets by three 2-byte integer fields (<structfield>pd_lower</structfield>,
from the page start to the start <structfield>pd_upper</structfield>, and
of unallocated space, to the end of unallocated space, and to the start of <structfield>pd_special</structfield>). These contain byte offsets
the special space. from the page start to the start of unallocated space, to the end of
The next 2 bytes of the page header, unallocated space, and to the start of the special space. The next 2
<structfield>pd_pagesize_version</structfield>, store both the page size bytes of the page header, <structfield>pd_pagesize_version</structfield>,
and a version indicator. Beginning with store both the page size and a version indicator. Beginning with
<productname>PostgreSQL</productname> 8.3 the version number is 4; <productname>PostgreSQL</productname> 8.3 the version number is 4;
<productname>PostgreSQL</productname> 8.1 and 8.2 used version number 3; <productname>PostgreSQL</productname> 8.1 and 8.2 used version number 3;
<productname>PostgreSQL</productname> 8.0 used version number 2; <productname>PostgreSQL</productname> 8.0 used version number 2;
@ -799,7 +799,7 @@ data. Empty in ordinary tables.</entry>
<tbody> <tbody>
<row> <row>
<entry>pd_lsn</entry> <entry>pd_lsn</entry>
<entry>XLogRecPtr</entry> <entry>PageXLogRecPtr</entry>
<entry>8 bytes</entry> <entry>8 bytes</entry>
<entry>LSN: next byte after last byte of xlog record for last change <entry>LSN: next byte after last byte of xlog record for last change
to this page</entry> to this page</entry>