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pageinspect: Support hash indexes.

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Patch by Jesper Pedersen and Ashutosh Sharma, with some error handling
improvements by me.  Tests from Peter Eisentraut.  Reviewed by Álvaro
Herrera, Michael Paquier, Jesper Pedersen, Jeff Janes, Peter
Eisentraut, Amit Kapila, Mithun Cy, and me.

Discussion: http://postgr.es/m/e2ac6c58-b93f-9dd9-f4e6-d6d30add7fdf@redhat.com
This commit is contained in:
Robert Haas
2017-02-02 14:12:58 -05:00
parent acd73ad1a1
commit 08bf6e5295
9 changed files with 995 additions and 10 deletions
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144
doc/src/sgml/pageinspect.sgml
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@ -486,6 +486,150 @@ test=# SELECT first_tid, nbytes, tids[0:5] AS some_tids
(170,30) | 376 | {"(170,30)","(170,31)","(170,32)","(170,33)","(170,34)"}
(173,44) | 197 | {"(173,44)","(173,45)","(173,46)","(173,47)","(173,48)"}
(7 rows)
</screen>
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2>
<sect2>
<title>Hash Functions</title>
<variablelist>
<varlistentry>
<term>
<function>hash_page_type(page bytea) returns text</function>
<indexterm>
<primary>hash_page_type</primary>
</indexterm>
</term>
<listitem>
<para>
<function>hash_page_type</function> returns page type of
the given <acronym>HASH</acronym> index page. For example:
<screen>
test=# SELECT hash_page_type(get_raw_page('con_hash_index', 0));
hash_page_type
----------------
metapage
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>hash_page_stats(page bytea) returns setof record</function>
<indexterm>
<primary>hash_page_stats</primary>
</indexterm>
</term>
<listitem>
<para>
<function>hash_page_stats</function> returns information about
a bucket or overflow page of a <acronym>HASH</acronym> index.
For example:
<screen>
test=# SELECT * FROM hash_page_stats(get_raw_page('con_hash_index', 1));
-[ RECORD 1 ]---+-----------
live_items | 407
dead_items | 0
page_size | 8192
free_size | 8
hasho_prevblkno | 4294967295
hasho_nextblkno | 8474
hasho_bucket | 0
hasho_flag | 66
hasho_page_id | 65408
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>hash_page_items(page bytea) returns setof record</function>
<indexterm>
<primary>hash_page_items</primary>
</indexterm>
</term>
<listitem>
<para>
<function>hash_page_items</function> returns information about
the data stored in a bucket or overflow page of a <acronym>HASH</acronym>
index page. For example:
<screen>
test=# SELECT * FROM hash_page_items(get_raw_page('con_hash_index', 1)) LIMIT 5;
itemoffset | ctid | data
------------+-----------+------------
1 | (899,77) | 1053474816
2 | (897,29) | 1053474816
3 | (894,207) | 1053474816
4 | (892,159) | 1053474816
5 | (890,111) | 1053474816
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>hash_bitmap_info(index oid, blkno int) returns record</function>
<indexterm>
<primary>hash_bitmap_info</primary>
</indexterm>
</term>
<listitem>
<para>
<function>hash_bitmap_info</function> shows the status of a bit
in the bitmap page for a particular overflow page of <acronym>HASH</acronym>
index. For example:
<screen>
test=# SELECT * FROM hash_bitmap_info('con_hash_index', 2052);
bitmapblkno | bitmapbit | bitstatus
-------------+-----------+-----------
65 | 3 | t
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>hash_metapage_info(page bytea) returns record</function>
<indexterm>
<primary>hash_metapage_info</primary>
</indexterm>
</term>
<listitem>
<para>
<function>hash_metapage_info</function> returns information stored
in meta page of a <acronym>HASH</acronym> index. For example:
<screen>
test=# SELECT * FROM hash_metapage_info(get_raw_page('con_hash_index', 0));
-[ RECORD 1 ]-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
magic | 105121344
version | 2
ntuples | 500500
ffactor | 40
bsize | 8152
bmsize | 4096
bmshift | 15
maxbucket | 12512
highmask | 16383
lowmask | 8191
ovflpoint | 14
firstfree | 1204
nmaps | 1
procid | 450
spares | {0,0,0,0,0,0,1,1,1,1,1,4,59,704,1204,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
mapp | {65,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}
</screen>
</para>
</listitem>