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Add functions to 'pageinspect' to inspect GiST indexes.

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Author: Andrey Borodin and me
Discussion: https://www.postgresql.org/message-id/3E4F9093-A1B5-4DF8-A292-0B48692E3954%40yandex-team.ru
This commit is contained in:
Heikki Linnakangas
2021-01-13 10:33:33 +02:00
parent df10ac625c
commit 756ab29124
7 changed files with 527 additions and 3 deletions
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89
doc/src/sgml/pageinspect.sgml
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@ -671,6 +671,95 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
</variablelist>
</sect2>
<sect2>
<title>GiST Functions</title>
<variablelist>
<varlistentry>
<term>
<function>gist_page_opaque_info(page bytea) returns record</function>
<indexterm>
<primary>gist_page_opaque_info</primary>
</indexterm>
</term>
<listitem>
<para>
<function>gist_page_opaque_info</function> returns information about
a <acronym>GiST</acronym> index opaque area, like the NSN, rightlink and
page type.
For example:
<screen>
test=# SELECT * FROM gist_page_opaque_info(get_raw_page('test_gist_idx', 2));
lsn | nsn | rightlink | flags
-----+-----+-----------+--------
0/1 | 0/0 | 1 | {leaf}
(1 row)
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>gist_page_items(page bytea, index oid) returns setof record</function>
<indexterm>
<primary>gist_page_items</primary>
</indexterm>
</term>
<listitem>
<para>
<function>gist_page_items</function> returns information about
the data stored in a page of <acronym>GiST</acronym> index. For example:
<screen>
test=# SELECT * FROM gist_page_items(get_raw_page('test_gist_idx', 0), 'test_gist_idx');
itemoffset | ctid | itemlen | keys
------------+-----------+---------+-------------------
1 | (1,65535) | 40 | (p)=((166,166))
2 | (2,65535) | 40 | (p)=((332,332))
3 | (3,65535) | 40 | (p)=((498,498))
4 | (4,65535) | 40 | (p)=((664,664))
5 | (5,65535) | 40 | (p)=((830,830))
6 | (6,65535) | 40 | (p)=((996,996))
7 | (7,65535) | 40 | (p)=((1000,1000))
(7 rows)
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>gist_page_items_bytea(page bytea) returns setof record</function>
<indexterm>
<primary>gist_page_items_bytea</primary>
</indexterm>
</term>
<listitem>
<para>
Same as <function>gist_page_items</function>, but returns the key data as a raw
bytea blob. For example:
<screen>
test=# SELECT * FROM gist_page_items_bytea(get_raw_page('test_gist_idx', 0));
itemoffset | ctid | itemlen | key_data
------------+-----------+---------+------------------------------------------------------------------------------------
1 | (1,65535) | 40 | \x00000100ffff28000000000000c064400000000000c06440000000000000f03f000000000000f03f
2 | (2,65535) | 40 | \x00000200ffff28000000000000c074400000000000c074400000000000e064400000000000e06440
3 | (3,65535) | 40 | \x00000300ffff28000000000000207f400000000000207f400000000000d074400000000000d07440
4 | (4,65535) | 40 | \x00000400ffff28000000000000c084400000000000c084400000000000307f400000000000307f40
5 | (5,65535) | 40 | \x00000500ffff28000000000000f089400000000000f089400000000000c884400000000000c88440
6 | (6,65535) | 40 | \x00000600ffff28000000000000208f400000000000208f400000000000f889400000000000f88940
7 | (7,65535) | 40 | \x00000700ffff28000000000000408f400000000000408f400000000000288f400000000000288f40
(7 rows)
</screen>
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>
<sect2>
<title>Hash Functions</title>