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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
pull/47/head
Michael Paquier 6 years ago
parent 59354ccef5
commit 58b4cb30a5
5 changed files with 153 additions and 224 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 174
      contrib/pageinspect/expected/page.out
  2. 138
      contrib/pageinspect/heapfuncs.c
  3. 5
      contrib/pageinspect/pageinspect--1.7--1.8.sql
  4. 42
      contrib/pageinspect/sql/page.sql
  5. 18
      doc/src/sgml/pageinspect.sgml

174
contrib/pageinspect/expected/page.out
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@ -86,127 +86,55 @@ SELECT * FROM fsm_page_contents(get_raw_page('test1', 'fsm', 0));
-- always be the same in all test runs. we show raw flags by
-- default: HEAP_XMIN_COMMITTED and HEAP_XMIN_INVALID.
VACUUM FREEZE test1;
SELECT t_infomask, t_infomask2, flags
SELECT t_infomask, t_infomask2, raw_flags, combined_flags
FROM heap_page_items(get_raw_page('test1', 0)),
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2) m(flags);
t_infomask | t_infomask2 | flags
------------+-------------+-----------------------------------------------------------
2816 | 2 | {HEAP_XMAX_INVALID,HEAP_XMIN_COMMITTED,HEAP_XMIN_INVALID}
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2);
t_infomask | t_infomask2 | raw_flags | combined_flags
------------+-------------+-----------------------------------------------------------+--------------------
2816 | 2 | {HEAP_XMIN_COMMITTED,HEAP_XMIN_INVALID,HEAP_XMAX_INVALID} | {HEAP_XMIN_FROZEN}
(1 row)
-- output the decoded flag HEAP_XMIN_FROZEN instead
SELECT t_infomask, t_infomask2, flags
SELECT t_infomask, t_infomask2, raw_flags, combined_flags
FROM heap_page_items(get_raw_page('test1', 0)),
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2, true) m(flags);
t_infomask | t_infomask2 | flags
------------+-------------+--------------------------------------
2816 | 2 | {HEAP_XMAX_INVALID,HEAP_XMIN_FROZEN}
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2);
t_infomask | t_infomask2 | raw_flags | combined_flags
------------+-------------+-----------------------------------------------------------+--------------------
2816 | 2 | {HEAP_XMIN_COMMITTED,HEAP_XMIN_INVALID,HEAP_XMAX_INVALID} | {HEAP_XMIN_FROZEN}
(1 row)
-- tests for decoding of combined flags
-- HEAP_XMAX_SHR_LOCK = (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)
SELECT heap_tuple_infomask_flags(x'0050'::int, 0, true);
heap_tuple_infomask_flags
---------------------------
{HEAP_XMAX_SHR_LOCK}
(1 row)
SELECT heap_tuple_infomask_flags(x'0050'::int, 0, false);
heap_tuple_infomask_flags
---------------------------------------------
{HEAP_XMAX_EXCL_LOCK,HEAP_XMAX_KEYSHR_LOCK}
SELECT * FROM heap_tuple_infomask_flags(x'0050'::int, 0);
raw_flags | combined_flags
---------------------------------------------+----------------------
{HEAP_XMAX_KEYSHR_LOCK,HEAP_XMAX_EXCL_LOCK} | {HEAP_XMAX_SHR_LOCK}
(1 row)
-- HEAP_XMIN_FROZEN = (HEAP_XMIN_COMMITTED | HEAP_XMIN_INVALID)
SELECT heap_tuple_infomask_flags(x'0300'::int, 0, true);
heap_tuple_infomask_flags
---------------------------
{HEAP_XMIN_FROZEN}
(1 row)
SELECT heap_tuple_infomask_flags(x'0300'::int, 0, false);
heap_tuple_infomask_flags
-----------------------------------------
{HEAP_XMIN_COMMITTED,HEAP_XMIN_INVALID}
SELECT * FROM heap_tuple_infomask_flags(x'0300'::int, 0);
raw_flags | combined_flags
-----------------------------------------+--------------------
{HEAP_XMIN_COMMITTED,HEAP_XMIN_INVALID} | {HEAP_XMIN_FROZEN}
(1 row)
-- HEAP_MOVED = (HEAP_MOVED_IN | HEAP_MOVED_OFF)
SELECT heap_tuple_infomask_flags(x'C000'::int, 0, true);
heap_tuple_infomask_flags
---------------------------
{HEAP_MOVED}
SELECT * FROM heap_tuple_infomask_flags(x'C000'::int, 0);
raw_flags | combined_flags
--------------------------------+----------------
{HEAP_MOVED_OFF,HEAP_MOVED_IN} | {HEAP_MOVED}
(1 row)
SELECT heap_tuple_infomask_flags(x'C000'::int, 0, false);
heap_tuple_infomask_flags
--------------------------------
{HEAP_MOVED_IN,HEAP_MOVED_OFF}
(1 row)
-- HEAP_LOCKED_UPGRADED = (HEAP_XMAX_IS_MULTI | HEAP_XMAX_LOCK_ONLY)
SELECT heap_tuple_infomask_flags(x'1080'::int, 0, true);
heap_tuple_infomask_flags
---------------------------
{HEAP_LOCKED_UPGRADED}
(1 row)
SELECT heap_tuple_infomask_flags(x'1080'::int, 0, false);
heap_tuple_infomask_flags
------------------------------------------
{HEAP_XMAX_LOCK_ONLY,HEAP_XMAX_IS_MULTI}
SELECT * FROM heap_tuple_infomask_flags(x'C000'::int, 0);
raw_flags | combined_flags
--------------------------------+----------------
{HEAP_MOVED_OFF,HEAP_MOVED_IN} | {HEAP_MOVED}
(1 row)
-- test all flags of t_infomask and t_infomask2
SELECT unnest(heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int, false))
AS flags ORDER BY 1;
flags
-----------------------
HEAP_COMBOCID
HEAP_HASEXTERNAL
HEAP_HASNULL
HEAP_HASOID_OLD
HEAP_HASVARWIDTH
HEAP_HOT_UPDATED
HEAP_KEYS_UPDATED
HEAP_MOVED_IN
HEAP_MOVED_OFF
HEAP_ONLY_TUPLE
HEAP_UPDATED
HEAP_XMAX_COMMITTED
HEAP_XMAX_EXCL_LOCK
HEAP_XMAX_INVALID
HEAP_XMAX_IS_MULTI
HEAP_XMAX_KEYSHR_LOCK
HEAP_XMAX_LOCK_ONLY
HEAP_XMIN_COMMITTED
HEAP_XMIN_INVALID
(19 rows)
SELECT unnest(heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int, true))
AS flags ORDER BY 1;
flags
---------------------
HEAP_COMBOCID
HEAP_HASEXTERNAL
HEAP_HASNULL
HEAP_HASOID_OLD
HEAP_HASVARWIDTH
HEAP_HOT_UPDATED
HEAP_KEYS_UPDATED
HEAP_MOVED
HEAP_ONLY_TUPLE
HEAP_UPDATED
HEAP_XMAX_COMMITTED
HEAP_XMAX_INVALID
HEAP_XMAX_IS_MULTI
HEAP_XMAX_LOCK_ONLY
HEAP_XMAX_SHR_LOCK
HEAP_XMIN_FROZEN
(16 rows)
SELECT unnest(heap_tuple_infomask_flags(-1, -1, false))
AS flags ORDER BY 1;
flags
SELECT unnest(raw_flags)
FROM heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int) ORDER BY 1;
unnest
-----------------------
HEAP_COMBOCID
HEAP_HASEXTERNAL
@ -229,38 +157,28 @@ SELECT unnest(heap_tuple_infomask_flags(-1, -1, false))
HEAP_XMIN_INVALID
(19 rows)
SELECT unnest(heap_tuple_infomask_flags(-1, -1, true))
AS flags ORDER BY 1;
flags
---------------------
HEAP_COMBOCID
HEAP_HASEXTERNAL
HEAP_HASNULL
HEAP_HASOID_OLD
HEAP_HASVARWIDTH
HEAP_HOT_UPDATED
HEAP_KEYS_UPDATED
SELECT unnest(combined_flags)
FROM heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int) ORDER BY 1;
unnest
--------------------
HEAP_MOVED
HEAP_ONLY_TUPLE
HEAP_UPDATED
HEAP_XMAX_COMMITTED
HEAP_XMAX_INVALID
HEAP_XMAX_IS_MULTI
HEAP_XMAX_LOCK_ONLY
HEAP_XMAX_SHR_LOCK
HEAP_XMIN_FROZEN
(16 rows)
(3 rows)
-- no flags
SELECT unnest(heap_tuple_infomask_flags(0, 0, false));
unnest
--------
(0 rows)
-- no flags at all
SELECT * FROM heap_tuple_infomask_flags(0, 0);
raw_flags | combined_flags
-----------+----------------
{} | {}
(1 row)
SELECT unnest(heap_tuple_infomask_flags(0, 0, true));
unnest
--------
(0 rows)
-- no combined flags
SELECT * FROM heap_tuple_infomask_flags(x'0010'::int, 0);
raw_flags | combined_flags
-------------------------+----------------
{HEAP_XMAX_KEYSHR_LOCK} | {}
(1 row)
DROP TABLE test1;
-- check that using any of these functions with a partitioned table or index

138
contrib/pageinspect/heapfuncs.c
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@ -507,99 +507,117 @@ PG_FUNCTION_INFO_V1(heap_tuple_infomask_flags);
Datum
heap_tuple_infomask_flags(PG_FUNCTION_ARGS)
{
#define HEAP_TUPLE_INFOMASK_COLS 2
Datum values[HEAP_TUPLE_INFOMASK_COLS];
bool nulls[HEAP_TUPLE_INFOMASK_COLS];
uint16 t_infomask = PG_GETARG_INT16(0);
uint16 t_infomask2 = PG_GETARG_INT16(1);
bool decode_combined = PG_GETARG_BOOL(2);
int cnt = 0;
ArrayType *a;
int bitcnt;
Datum *d;
Datum *flags;
TupleDesc tupdesc;
HeapTuple tuple;
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to use raw page functions")));
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
bitcnt = pg_popcount((const char *) &t_infomask, sizeof(uint16)) +
pg_popcount((const char *) &t_infomask2, sizeof(uint16));
/* If no flags, return an empty array */
/* Initialize values and NULL flags arrays */
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
/* If no flags, return a set of empty arrays */
if (bitcnt <= 0)
PG_RETURN_POINTER(construct_empty_array(TEXTOID));
{
values[0] = PointerGetDatum(construct_empty_array(TEXTOID));
values[1] = PointerGetDatum(construct_empty_array(TEXTOID));
tuple = heap_form_tuple(tupdesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}
d = (Datum *) palloc0(sizeof(Datum) * bitcnt);
/* build set of raw flags */
flags = (Datum *) palloc0(sizeof(Datum) * bitcnt);
/* decode t_infomask */
if ((t_infomask & HEAP_HASNULL) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_HASNULL");
flags[cnt++] = CStringGetTextDatum("HEAP_HASNULL");
if ((t_infomask & HEAP_HASVARWIDTH) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_HASVARWIDTH");
flags[cnt++] = CStringGetTextDatum("HEAP_HASVARWIDTH");
if ((t_infomask & HEAP_HASEXTERNAL) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_HASEXTERNAL");
flags[cnt++] = CStringGetTextDatum("HEAP_HASEXTERNAL");
if ((t_infomask & HEAP_HASOID_OLD) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_HASOID_OLD");
flags[cnt++] = CStringGetTextDatum("HEAP_HASOID_OLD");
if ((t_infomask & HEAP_XMAX_KEYSHR_LOCK) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_KEYSHR_LOCK");
if ((t_infomask & HEAP_COMBOCID) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_COMBOCID");
flags[cnt++] = CStringGetTextDatum("HEAP_COMBOCID");
if ((t_infomask & HEAP_XMAX_EXCL_LOCK) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_EXCL_LOCK");
if ((t_infomask & HEAP_XMAX_LOCK_ONLY) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_LOCK_ONLY");
if ((t_infomask & HEAP_XMIN_COMMITTED) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_XMIN_COMMITTED");
if ((t_infomask & HEAP_XMIN_INVALID) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_XMIN_INVALID");
if ((t_infomask & HEAP_XMAX_COMMITTED) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_COMMITTED");
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_COMMITTED");
if ((t_infomask & HEAP_XMAX_INVALID) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_INVALID");
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_INVALID");
if ((t_infomask & HEAP_XMAX_IS_MULTI) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_IS_MULTI");
if ((t_infomask & HEAP_UPDATED) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_UPDATED");
/* decode combined masks of t_infomaks */
if (decode_combined && (t_infomask & HEAP_XMAX_SHR_LOCK) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_SHR_LOCK");
else
{
if ((t_infomask & HEAP_XMAX_EXCL_LOCK) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_EXCL_LOCK");
if ((t_infomask & HEAP_XMAX_KEYSHR_LOCK) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_KEYSHR_LOCK");
}
if (decode_combined && (t_infomask & HEAP_XMIN_FROZEN) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMIN_FROZEN");
else
{
if ((t_infomask & HEAP_XMIN_COMMITTED) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMIN_COMMITTED");
if ((t_infomask & HEAP_XMIN_INVALID) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMIN_INVALID");
}
if (decode_combined && (t_infomask & HEAP_MOVED) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_MOVED");
else
{
if ((t_infomask & HEAP_MOVED_IN) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_MOVED_IN");
if ((t_infomask & HEAP_MOVED_OFF) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_MOVED_OFF");
}
if (decode_combined && HEAP_LOCKED_UPGRADED(t_infomask))
d[cnt++] = CStringGetTextDatum("HEAP_LOCKED_UPGRADED");
else
{
if (HEAP_XMAX_IS_LOCKED_ONLY(t_infomask))
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_LOCK_ONLY");
if ((t_infomask & HEAP_XMAX_IS_MULTI) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_XMAX_IS_MULTI");
}
flags[cnt++] = CStringGetTextDatum("HEAP_UPDATED");
if ((t_infomask & HEAP_MOVED_OFF) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_MOVED_OFF");
if ((t_infomask & HEAP_MOVED_IN) != 0)
flags[cnt++] = CStringGetTextDatum("HEAP_MOVED_IN");
/* decode t_infomask2 */
if ((t_infomask2 & HEAP_KEYS_UPDATED) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_KEYS_UPDATED");
flags[cnt++] = CStringGetTextDatum("HEAP_KEYS_UPDATED");
if ((t_infomask2 & HEAP_HOT_UPDATED) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_HOT_UPDATED");
flags[cnt++] = CStringGetTextDatum("HEAP_HOT_UPDATED");
if ((t_infomask2 & HEAP_ONLY_TUPLE) != 0)
d[cnt++] = CStringGetTextDatum("HEAP_ONLY_TUPLE");
flags[cnt++] = CStringGetTextDatum("HEAP_ONLY_TUPLE");
/* build value */
Assert(cnt <= bitcnt);
a = construct_array(d, cnt, TEXTOID, -1, false, 'i');
a = construct_array(flags, cnt, TEXTOID, -1, false, 'i');
values[0] = PointerGetDatum(a);
pfree(d);
/*
* Build set of combined flags. Use the same array as previously, this
* keeps the code simple.
*/
cnt = 0;
MemSet(flags, 0, sizeof(Datum) * bitcnt);
/* decode combined masks of t_infomask */
if ((t_infomask & HEAP_XMAX_SHR_LOCK) == HEAP_XMAX_SHR_LOCK)
flags[cnt++] = CStringGetTextDatum("HEAP_XMAX_SHR_LOCK");
if ((t_infomask & HEAP_XMIN_FROZEN) == HEAP_XMIN_FROZEN)
flags[cnt++] = CStringGetTextDatum("HEAP_XMIN_FROZEN");
if ((t_infomask & HEAP_MOVED) == HEAP_MOVED)
flags[cnt++] = CStringGetTextDatum("HEAP_MOVED");
/* Build an empty array if there are no combined flags */
if (cnt == 0)
a = construct_empty_array(TEXTOID);
else
a = construct_array(flags, cnt, TEXTOID, -1, false, 'i');
pfree(flags);
values[1] = PointerGetDatum(a);
PG_RETURN_POINTER(a);
/* Returns the record as Datum */
tuple = heap_form_tuple(tupdesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(tuple));
}

5
contrib/pageinspect/pageinspect--1.7--1.8.sql
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@ -9,7 +9,8 @@
CREATE FUNCTION heap_tuple_infomask_flags(
t_infomask integer,
t_infomask2 integer,
decode_combined boolean DEFAULT false)
RETURNS text[]
raw_flags OUT text[],
combined_flags OUT text[])
RETURNS record
AS 'MODULE_PATHNAME', 'heap_tuple_infomask_flags'
LANGUAGE C STRICT PARALLEL SAFE;

42
contrib/pageinspect/sql/page.sql
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@ -36,42 +36,34 @@ SELECT * FROM fsm_page_contents(get_raw_page('test1', 'fsm', 0));
-- default: HEAP_XMIN_COMMITTED and HEAP_XMIN_INVALID.
VACUUM FREEZE test1;
SELECT t_infomask, t_infomask2, flags
SELECT t_infomask, t_infomask2, raw_flags, combined_flags
FROM heap_page_items(get_raw_page('test1', 0)),
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2) m(flags);
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2);
-- output the decoded flag HEAP_XMIN_FROZEN instead
SELECT t_infomask, t_infomask2, flags
SELECT t_infomask, t_infomask2, raw_flags, combined_flags
FROM heap_page_items(get_raw_page('test1', 0)),
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2, true) m(flags);
LATERAL heap_tuple_infomask_flags(t_infomask, t_infomask2);
-- tests for decoding of combined flags
-- HEAP_XMAX_SHR_LOCK = (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)
SELECT heap_tuple_infomask_flags(x'0050'::int, 0, true);
SELECT heap_tuple_infomask_flags(x'0050'::int, 0, false);
SELECT * FROM heap_tuple_infomask_flags(x'0050'::int, 0);
-- HEAP_XMIN_FROZEN = (HEAP_XMIN_COMMITTED | HEAP_XMIN_INVALID)
SELECT heap_tuple_infomask_flags(x'0300'::int, 0, true);
SELECT heap_tuple_infomask_flags(x'0300'::int, 0, false);
SELECT * FROM heap_tuple_infomask_flags(x'0300'::int, 0);
-- HEAP_MOVED = (HEAP_MOVED_IN | HEAP_MOVED_OFF)
SELECT heap_tuple_infomask_flags(x'C000'::int, 0, true);
SELECT heap_tuple_infomask_flags(x'C000'::int, 0, false);
-- HEAP_LOCKED_UPGRADED = (HEAP_XMAX_IS_MULTI | HEAP_XMAX_LOCK_ONLY)
SELECT heap_tuple_infomask_flags(x'1080'::int, 0, true);
SELECT heap_tuple_infomask_flags(x'1080'::int, 0, false);
SELECT * FROM heap_tuple_infomask_flags(x'C000'::int, 0);
SELECT * FROM heap_tuple_infomask_flags(x'C000'::int, 0);
-- test all flags of t_infomask and t_infomask2
SELECT unnest(heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int, false))
AS flags ORDER BY 1;
SELECT unnest(heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int, true))
AS flags ORDER BY 1;
SELECT unnest(heap_tuple_infomask_flags(-1, -1, false))
AS flags ORDER BY 1;
SELECT unnest(heap_tuple_infomask_flags(-1, -1, true))
AS flags ORDER BY 1;
-- no flags
SELECT unnest(heap_tuple_infomask_flags(0, 0, false));
SELECT unnest(heap_tuple_infomask_flags(0, 0, true));
SELECT unnest(raw_flags)
FROM heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int) ORDER BY 1;
SELECT unnest(combined_flags)
FROM heap_tuple_infomask_flags(x'FFFF'::int, x'FFFF'::int) ORDER BY 1;
-- no flags at all
SELECT * FROM heap_tuple_infomask_flags(0, 0);
-- no combined flags
SELECT * FROM heap_tuple_infomask_flags(x'0010'::int, 0);
DROP TABLE test1;

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

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