Add to pageinspect function to make t_infomask/t_infomask2 human-readable

Flags of t_infomask and t_infomask2 for each tuple are already included
in the information returned by heap_page_items as integers, and we
lacked a way to make that information human-readable.

Per discussion, the function includes an option which controls if
combined flags should be decomposed or not.  The default is false, to
not decompose combined flags.

The module is bumped to version 1.8.

Author: Craig Ringer, Sawada Masahiko
Reviewed-by: Peter Geoghegan, Robert Haas, Álvaro Herrera, Moon Insung,
Amit Kapila, Michael Paquier, Tomas Vondra
Discussion: https://postgr.es/m/CAMsr+YEY7jeaXOb+oX+RhDyOFuTMdmHjGsBxL=igCm03J0go9Q@mail.gmail.com

1 files changed, 109 insertions, 0 deletions

diff --git a/contrib/pageinspect/heapfuncs.c b/contrib/pageinspect/heapfuncs.c
index 64a6e351d5..68f16cd400 100644
--- a/contrib/pageinspect/heapfuncs.c
+++ b/contrib/pageinspect/heapfuncs.c
@@ -33,6 +33,7 @@
 #include "catalog/pg_am_d.h"
 #include "catalog/pg_type.h"
 #include "miscadmin.h"
+#include "port/pg_bitutils.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/rel.h"
@@ -494,3 +495,111 @@ tuple_data_split(PG_FUNCTION_ARGS)
 
 	PG_RETURN_ARRAYTYPE_P(res);
 }
+
+/*
+ * heap_tuple_infomask_flags
+ *
+ * Decode into a human-readable format t_infomask and t_infomask2 associated
+ * to a tuple.  All the flags are described in access/htup_details.h.
+ */
+PG_FUNCTION_INFO_V1(heap_tuple_infomask_flags);
+
+Datum
+heap_tuple_infomask_flags(PG_FUNCTION_ARGS)
+{
+	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;
+
+	if (!superuser())
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to use raw page functions")));
+
+	bitcnt = pg_popcount((const char *) &t_infomask, sizeof(uint16)) +
+		pg_popcount((const char *) &t_infomask2, sizeof(uint16));
+
+	/* If no flags, return an empty array */
+	if (bitcnt <= 0)
+		PG_RETURN_POINTER(construct_empty_array(TEXTOID));
+
+	d = (Datum *) palloc0(sizeof(Datum) * bitcnt);
+
+	/* decode t_infomask */
+	if ((t_infomask & HEAP_HASNULL) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_HASNULL");
+	if ((t_infomask & HEAP_HASVARWIDTH) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_HASVARWIDTH");
+	if ((t_infomask & HEAP_HASEXTERNAL) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_HASEXTERNAL");
+	if ((t_infomask & HEAP_HASOID_OLD) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_HASOID_OLD");
+	if ((t_infomask & HEAP_COMBOCID) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_COMBOCID");
+	if ((t_infomask & HEAP_XMAX_COMMITTED) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_XMAX_COMMITTED");
+	if ((t_infomask & HEAP_XMAX_INVALID) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_XMAX_INVALID");
+	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");
+	}
+
+	/* decode t_infomask2 */
+	if ((t_infomask2 & HEAP_KEYS_UPDATED) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_KEYS_UPDATED");
+	if ((t_infomask2 & HEAP_HOT_UPDATED) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_HOT_UPDATED");
+	if ((t_infomask2 & HEAP_ONLY_TUPLE) != 0)
+		d[cnt++] = CStringGetTextDatum("HEAP_ONLY_TUPLE");
+
+	Assert(cnt <= bitcnt);
+	a = construct_array(d, cnt, TEXTOID, -1, false, 'i');
+
+	pfree(d);
+
+	PG_RETURN_POINTER(a);
+}