Move IS [NOT] NULL handling from BRIN support functions

The handling of IS [NOT] NULL clauses is independent of an opclass, and
most of the code was exactly the same in both minmax and inclusion. So
instead move the code from support procedures to the AM.

This simplifies the code - especially the support procedures - quite a
bit, as they don't need to care about NULL values and flags at all. It
also means the IS [NOT] NULL clauses can be evaluated without invoking
the support procedure.

Author: Tomas Vondra <tomas.vondra@postgresql.org>
Author: Nikita Glukhov <n.gluhov@postgrespro.ru>
Reviewed-by: Nikita Glukhov <n.gluhov@postgrespro.ru>
Reviewed-by: Mark Dilger <hornschnorter@gmail.com>
Reviewed-by: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Masahiko Sawada <masahiko.sawada@enterprisedb.com>
Reviewed-by: John Naylor <john.naylor@enterprisedb.com>
Discussion: https://postgr.es/m/c1138ead-7668-f0e1-0638-c3be3237e812@2ndquadrant.com

src/backend/access/brin/brin_inclusion.c

@@ -110,6 +110,7 @@ brin_inclusion_opcinfo(PG_FUNCTION_ARGS)
 	 */
 	result = palloc0(MAXALIGN(SizeofBrinOpcInfo(3)) + sizeof(InclusionOpaque));
 	result->oi_nstored = 3;
+	result->oi_regular_nulls = true;
 	result->oi_opaque = (InclusionOpaque *)
 		MAXALIGN((char *) result + SizeofBrinOpcInfo(3));
 
@@ -141,7 +142,7 @@ brin_inclusion_add_value(PG_FUNCTION_ARGS)
 	BrinDesc   *bdesc = (BrinDesc *) PG_GETARG_POINTER(0);
 	BrinValues *column = (BrinValues *) PG_GETARG_POINTER(1);
 	Datum		newval = PG_GETARG_DATUM(2);
-	bool		isnull = PG_GETARG_BOOL(3);
+	bool		isnull PG_USED_FOR_ASSERTS_ONLY = PG_GETARG_BOOL(3);
 	Oid			colloid = PG_GET_COLLATION();
 	FmgrInfo   *finfo;
 	Datum		result;
@@ -149,18 +150,7 @@ brin_inclusion_add_value(PG_FUNCTION_ARGS)
 	AttrNumber	attno;
 	Form_pg_attribute attr;
 
-	/*
-	 * If the new value is null, we record that we saw it if it's the first
-	 * one; otherwise, there's nothing to do.
-	 */
-	if (isnull)
-	{
-		if (column->bv_hasnulls)
-			PG_RETURN_BOOL(false);
-
-		column->bv_hasnulls = true;
-		PG_RETURN_BOOL(true);
-	}
+	Assert(!isnull);
 
 	attno = column->bv_attno;
 	attr = TupleDescAttr(bdesc->bd_tupdesc, attno - 1);
@@ -268,52 +258,9 @@ brin_inclusion_consistent(PG_FUNCTION_ARGS)
 	int			nkeys = PG_GETARG_INT32(3);
 	Oid			colloid = PG_GET_COLLATION();
 	int			keyno;
-	bool		has_regular_keys = false;
-
-	/* Handle IS NULL/IS NOT NULL tests */
-	for (keyno = 0; keyno < nkeys; keyno++)
-	{
-		ScanKey		key = keys[keyno];
 
-		Assert(key->sk_attno == column->bv_attno);
-
-		/* Skip regular scan keys (and remember that we have some). */
-		if ((!key->sk_flags & SK_ISNULL))
-		{
-			has_regular_keys = true;
-			continue;
-		}
-
-		if (key->sk_flags & SK_SEARCHNULL)
-		{
-			if (column->bv_allnulls || column->bv_hasnulls)
-				continue;		/* this key is fine, continue */
-
-			PG_RETURN_BOOL(false);
-		}
-
-		/*
-		 * For IS NOT NULL, we can only skip ranges that are known to have
-		 * only nulls.
-		 */
-		if (key->sk_flags & SK_SEARCHNOTNULL)
-		{
-			if (column->bv_allnulls)
-				PG_RETURN_BOOL(false);
-
-			continue;
-		}
-
-		/*
-		 * Neither IS NULL nor IS NOT NULL was used; assume all indexable
-		 * operators are strict and return false.
-		 */
-		PG_RETURN_BOOL(false);
-	}
-
-	/* If there are no regular keys, the page range is considered consistent. */
-	if (!has_regular_keys)
-		PG_RETURN_BOOL(true);
+	/* make sure we got some scan keys */
+	Assert((nkeys > 0) && (keys != NULL));
 
 	/*
 	 * If is all nulls, it cannot possibly be consistent (at this point we
@@ -331,9 +278,8 @@ brin_inclusion_consistent(PG_FUNCTION_ARGS)
 	{
 		ScanKey		key = keys[keyno];
 
-		/* Skip IS NULL/IS NOT NULL keys (already handled above). */
-		if (key->sk_flags & SK_ISNULL)
-			continue;
+		/* NULL keys are handled and filtered-out in bringetbitmap */
+		Assert(!(key->sk_flags & SK_ISNULL));
 
 		/*
 		 * When there are multiple scan keys, failure to meet the criteria for
@@ -574,37 +520,11 @@ brin_inclusion_union(PG_FUNCTION_ARGS)
 	Datum		result;
 
 	Assert(col_a->bv_attno == col_b->bv_attno);
-
-	/* Adjust "hasnulls". */
-	if (!col_a->bv_hasnulls && col_b->bv_hasnulls)
-		col_a->bv_hasnulls = true;
-
-	/* If there are no values in B, there's nothing left to do. */
-	if (col_b->bv_allnulls)
-		PG_RETURN_VOID();
+	Assert(!col_a->bv_allnulls && !col_b->bv_allnulls);
 
 	attno = col_a->bv_attno;
 	attr = TupleDescAttr(bdesc->bd_tupdesc, attno - 1);
 
-	/*
-	 * Adjust "allnulls".  If A doesn't have values, just copy the values from
-	 * B into A, and we're done.  We cannot run the operators in this case,
-	 * because values in A might contain garbage.  Note we already established
-	 * that B contains values.
-	 */
-	if (col_a->bv_allnulls)
-	{
-		col_a->bv_allnulls = false;
-		col_a->bv_values[INCLUSION_UNION] =
-			datumCopy(col_b->bv_values[INCLUSION_UNION],
-					  attr->attbyval, attr->attlen);
-		col_a->bv_values[INCLUSION_UNMERGEABLE] =
-			col_b->bv_values[INCLUSION_UNMERGEABLE];
-		col_a->bv_values[INCLUSION_CONTAINS_EMPTY] =
-			col_b->bv_values[INCLUSION_CONTAINS_EMPTY];
-		PG_RETURN_VOID();
-	}
-
 	/* If B includes empty elements, mark A similarly, if needed. */
 	if (!DatumGetBool(col_a->bv_values[INCLUSION_CONTAINS_EMPTY]) &&
 		DatumGetBool(col_b->bv_values[INCLUSION_CONTAINS_EMPTY]))

src/backend/access/brin/brin_minmax.c

@@ -48,6 +48,7 @@ brin_minmax_opcinfo(PG_FUNCTION_ARGS)
 	result = palloc0(MAXALIGN(SizeofBrinOpcInfo(2)) +
 					 sizeof(MinmaxOpaque));
 	result->oi_nstored = 2;
+	result->oi_regular_nulls = true;
 	result->oi_opaque = (MinmaxOpaque *)
 		MAXALIGN((char *) result + SizeofBrinOpcInfo(2));
 	result->oi_typcache[0] = result->oi_typcache[1] =
@@ -69,7 +70,7 @@ brin_minmax_add_value(PG_FUNCTION_ARGS)
 	BrinDesc   *bdesc = (BrinDesc *) PG_GETARG_POINTER(0);
 	BrinValues *column = (BrinValues *) PG_GETARG_POINTER(1);
 	Datum		newval = PG_GETARG_DATUM(2);
-	bool		isnull = PG_GETARG_DATUM(3);
+	bool		isnull PG_USED_FOR_ASSERTS_ONLY = PG_GETARG_DATUM(3);
 	Oid			colloid = PG_GET_COLLATION();
 	FmgrInfo   *cmpFn;
 	Datum		compar;
@@ -77,18 +78,7 @@ brin_minmax_add_value(PG_FUNCTION_ARGS)
 	Form_pg_attribute attr;
 	AttrNumber	attno;
 
-	/*
-	 * If the new value is null, we record that we saw it if it's the first
-	 * one; otherwise, there's nothing to do.
-	 */
-	if (isnull)
-	{
-		if (column->bv_hasnulls)
-			PG_RETURN_BOOL(false);
-
-		column->bv_hasnulls = true;
-		PG_RETURN_BOOL(true);
-	}
+	Assert(!isnull);
 
 	attno = column->bv_attno;
 	attr = TupleDescAttr(bdesc->bd_tupdesc, attno - 1);
@@ -156,52 +146,9 @@ brin_minmax_consistent(PG_FUNCTION_ARGS)
 	int			nkeys = PG_GETARG_INT32(3);
 	Oid			colloid = PG_GET_COLLATION();
 	int			keyno;
-	bool		has_regular_keys = false;
-
-	/* handle IS NULL/IS NOT NULL tests */
-	for (keyno = 0; keyno < nkeys; keyno++)
-	{
-		ScanKey		key = keys[keyno];
-
-		Assert(key->sk_attno == column->bv_attno);
-
-		/* Skip regular scan keys (and remember that we have some). */
-		if ((!key->sk_flags & SK_ISNULL))
-		{
-			has_regular_keys = true;
-			continue;
-		}
 
-		if (key->sk_flags & SK_SEARCHNULL)
-		{
-			if (column->bv_allnulls || column->bv_hasnulls)
-				continue;		/* this key is fine, continue */
-
-			PG_RETURN_BOOL(false);
-		}
-
-		/*
-		 * For IS NOT NULL, we can only skip ranges that are known to have
-		 * only nulls.
-		 */
-		if (key->sk_flags & SK_SEARCHNOTNULL)
-		{
-			if (column->bv_allnulls)
-				PG_RETURN_BOOL(false);
-
-			continue;
-		}
-
-		/*
-		 * Neither IS NULL nor IS NOT NULL was used; assume all indexable
-		 * operators are strict and return false.
-		 */
-		PG_RETURN_BOOL(false);
-	}
-
-	/* If there are no regular keys, the page range is considered consistent. */
-	if (!has_regular_keys)
-		PG_RETURN_BOOL(true);
+	/* make sure we got some scan keys */
+	Assert((nkeys > 0) && (keys != NULL));
 
 	/*
 	 * If is all nulls, it cannot possibly be consistent (at this point we
@@ -215,9 +162,8 @@ brin_minmax_consistent(PG_FUNCTION_ARGS)
 	{
 		ScanKey		key = keys[keyno];
 
-		/* ignore IS NULL/IS NOT NULL tests handled above */
-		if (key->sk_flags & SK_ISNULL)
-			continue;
+		/* NULL keys are handled and filtered-out in bringetbitmap */
+		Assert(!(key->sk_flags & SK_ISNULL));
 
 		/*
 		 * When there are multiple scan keys, failure to meet the criteria for
@@ -307,34 +253,11 @@ brin_minmax_union(PG_FUNCTION_ARGS)
 	bool		needsadj;
 
 	Assert(col_a->bv_attno == col_b->bv_attno);
-
-	/* Adjust "hasnulls" */
-	if (!col_a->bv_hasnulls && col_b->bv_hasnulls)
-		col_a->bv_hasnulls = true;
-
-	/* If there are no values in B, there's nothing left to do */
-	if (col_b->bv_allnulls)
-		PG_RETURN_VOID();
+	Assert(!col_a->bv_allnulls && !col_b->bv_allnulls);
 
 	attno = col_a->bv_attno;
 	attr = TupleDescAttr(bdesc->bd_tupdesc, attno - 1);
 
-	/*
-	 * Adjust "allnulls".  If A doesn't have values, just copy the values from
-	 * B into A, and we're done.  We cannot run the operators in this case,
-	 * because values in A might contain garbage.  Note we already established
-	 * that B contains values.
-	 */
-	if (col_a->bv_allnulls)
-	{
-		col_a->bv_allnulls = false;
-		col_a->bv_values[0] = datumCopy(col_b->bv_values[0],
-										attr->attbyval, attr->attlen);
-		col_a->bv_values[1] = datumCopy(col_b->bv_values[1],
-										attr->attbyval, attr->attlen);
-		PG_RETURN_VOID();
-	}
-
 	/* Adjust minimum, if B's min is less than A's min */
 	finfo = minmax_get_strategy_procinfo(bdesc, attno, attr->atttypid,
 										 BTLessStrategyNumber);

src/include/access/brin_internal.h

@@ -27,6 +27,9 @@ typedef struct BrinOpcInfo
 	/* Number of columns stored in an index column of this opclass */
 	uint16		oi_nstored;
 
+	/* Regular processing of NULLs in BrinValues? */
+	bool		oi_regular_nulls;
+
 	/* Opaque pointer for the opclass' private use */
 	void	   *oi_opaque;