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Redesign pageinspect function printing infomask bits

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After more discussion, the new function added by ddbd5d8 could have been
designed in a better way.  Based on an idea from Álvaro, instead of
returning one column which includes both the raw and combined flags, use
two columns, with one for the raw flags and one for the combined flags.

This also takes care of some issues with HEAP_LOCKED_UPGRADED and
HEAP_XMAX_IS_LOCKED_ONLY which are not really combined flags as they
depend on conditions defined by other raw bits, as mentioned by Amit.

While on it, fix an extra issue with combined flags.  A combined flag
was returned if at least one of its bits was set, but all its bits need
to be set to include it in the result.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera, Amit Kapila
Discussion: https://postgr.es/m/20190913114950.GA3824@alvherre.pgsql
This commit is contained in:
Michael Paquier
2019-09-19 11:01:52 +09:00
parent 59354ccef5
commit 58b4cb30a5
5 changed files with 153 additions and 224 deletions
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18
doc/src/sgml/pageinspect.sgml
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@ -244,7 +244,7 @@ test=# SELECT * FROM heap_page_item_attrs(get_raw_page('pg_class', 0), 'pg_class
<varlistentry>
<term>
<function>heap_tuple_infomask_flags(t_infomask integer, t_infomask2 integer, decode_combined bool) returns text[]</function>
<function>heap_tuple_infomask_flags(t_infomask integer, t_infomask2 integer) returns record</function>
<indexterm>
<primary>heap_tuple_infomask_flags</primary>
</indexterm>
@ -255,21 +255,21 @@ test=# SELECT * FROM heap_page_item_attrs(get_raw_page('pg_class', 0), 'pg_class
<structfield>t_infomask</structfield> and
<structfield>t_infomask2</structfield> returned by
<function>heap_page_items</function> into a human-readable
array of flag names. For example:
set of arrays made of flag names, with one column for all
the flags and one column for combined flags. For example:
<screen>
test=# SELECT t_ctid, heap_tuple_infomask_flags(t_infomask, t_infomask2) AS flags
FROM heap_page_items(get_raw_page('pg_class', 0))
test=# SELECT t_ctid, raw_flags, combined_flags
FROM heap_page_items(get_raw_page('pg_class', 0)),
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2)
WHERE t_infomask IS NOT NULL OR t_infomask2 IS NOT NULL;
</screen>
This function should be called with the same arguments as the return
attributes of <function>heap_page_items</function>.
</para>
<para>
If <parameter>decode_combined</parameter> is <literal>true</literal>,
combined flags like <literal>HEAP_XMIN_FROZEN</literal> are
returned instead of raw flags (<literal>HEAP_XMIN_COMMITTED</literal>
and <literal>HEAP_XMIN_INVALID</literal> in this case). Default value
is <literal>false</literal>.
Combined flags are displayed for source-level macros that take into
account the value of more than one raw bit, such as
<literal>HEAP_XMIN_FROZEN</literal>.
</para>
<para>
See <filename>src/include/access/htup_details.h</filename> for