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Improve pageinspect module

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Now pageinspect can show data stored in the heap tuple.

Nikolay Shaplov
This commit is contained in:
Teodor Sigaev
2015-11-25 16:31:55 +03:00
parent 13b30c16f3
commit d6061f83a1
5 changed files with 411 additions and 19 deletions
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57
doc/src/sgml/pageinspect.sgml
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@ -93,9 +93,10 @@ test=# SELECT * FROM page_header(get_raw_page('pg_class', 0));
<listitem>
<para>
<function>heap_page_items</function> shows all line pointers on a heap
page. For those line pointers that are in use, tuple headers are also
shown. All tuples are shown, whether or not the tuples were visible to
an MVCC snapshot at the time the raw page was copied.
page. For those line pointers that are in use, tuple headers as well
as tuple raw data are also shown. All tuples are shown, whether or not
the tuples were visible to an MVCC snapshot at the time the raw page
was copied.
</para>
<para>
A heap page image obtained with <function>get_raw_page</function> should
@ -110,6 +111,56 @@ test=# SELECT * FROM heap_page_items(get_raw_page('pg_class', 0));
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>tuple_data_split(rel_oid, t_data bytea, t_infomask integer, t_infomask2 integer, t_bits text [, do_detoast bool]) returns bytea[]</function>
<indexterm>
<primary>tuple_data_split</primary>
</indexterm>
</term>
<listitem>
<para>
<function>tuple_data_split</function> splits tuple data into attributes
in the same way as backend internals.
<screen>
test=# SELECT tuple_data_split('pg_class'::regclass, t_data, t_infomask, t_infomask2, t_bits) FROM heap_page_items(get_raw_page('pg_class', 0));
</screen>
This function should be called with the same arguments as the return
attributes of <function>heap_page_items</function>.
</para>
<para>
If <parameter>do_detoast</parameter> is <literal>true</literal>,
attribute that will be detoasted as needed. Default value is
<literal>false</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>heap_page_item_attrs(rel_oid, t_data bytea, [, do_detoast bool]) returns bytea[]</function>
<indexterm>
<primary>heap_page_item_attrs</primary>
</indexterm>
</term>
<listitem>
<para>
<function>heap_page_item_attrs</function> is equivalent to
<function>heap_page_items</function> except that it returns
tuple raw data as an array of attributes that can optionally
be detoasted by <parameter>do_detoast</parameter> which is
<literal>false</literal> by default.
</para>
<para>
A heap page image obtained with <function>get_raw_page</function> should
be passed as argument. For example:
<screen>
test=# SELECT * FROM heap_page_item_attrs(get_raw_page('pg_class', 0), 'pg_class'::regclass);
</screen>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<function>bt_metap(relname text) returns record</function>