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

Author: tvondra

src/backend/access/brin/brin.c

@@ -35,6 +35,7 @@
 #include "storage/freespace.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
+#include "utils/datum.h"
 #include "utils/index_selfuncs.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
@@ -77,7 +78,9 @@ static void form_and_insert_tuple(BrinBuildState *state);
 static void union_tuples(BrinDesc *bdesc, BrinMemTuple *a,
 						 BrinTuple *b);
 static void brin_vacuum_scan(Relation idxrel, BufferAccessStrategy strategy);
-
+static bool add_values_to_range(Relation idxRel, BrinDesc *bdesc,
+								BrinMemTuple *dtup, Datum *values, bool *nulls);
+static bool check_null_keys(BrinValues *bval, ScanKey *nullkeys, int nnullkeys);
 
 /*
  * BRIN handler function: return IndexAmRoutine with access method parameters
@@ -179,7 +182,6 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
 		OffsetNumber off;
 		BrinTuple  *brtup;
 		BrinMemTuple *dtup;
-		int			keyno;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -243,31 +245,7 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
 
 		dtup = brin_deform_tuple(bdesc, brtup, NULL);
 
-		/*
-		 * Compare the key values of the new tuple to the stored index values;
-		 * our deformed tuple will get updated if the new tuple doesn't fit
-		 * the original range (note this means we can't break out of the loop
-		 * early). Make a note of whether this happens, so that we know to
-		 * insert the modified tuple later.
-		 */
-		for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
-		{
-			Datum		result;
-			BrinValues *bval;
-			FmgrInfo   *addValue;
-
-			bval = &dtup->bt_columns[keyno];
-			addValue = index_getprocinfo(idxRel, keyno + 1,
-										 BRIN_PROCNUM_ADDVALUE);
-			result = FunctionCall4Coll(addValue,
-									   idxRel->rd_indcollation[keyno],
-									   PointerGetDatum(bdesc),
-									   PointerGetDatum(bval),
-									   values[keyno],
-									   nulls[keyno]);
-			/* if that returned true, we need to insert the updated tuple */
-			need_insert |= DatumGetBool(result);
-		}
+		need_insert = add_values_to_range(idxRel, bdesc, dtup, values, nulls);
 
 		if (!need_insert)
 		{
@@ -390,8 +368,10 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 	BrinMemTuple *dtup;
 	BrinTuple  *btup = NULL;
 	Size		btupsz = 0;
-	ScanKey   **keys;
-	int		   *nkeys;
+	ScanKey   **keys,
+			  **nullkeys;
+	int		   *nkeys,
+			   *nnullkeys;
 	int			keyno;
 
 	opaque = (BrinOpaque *) scan->opaque;
@@ -420,13 +400,18 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 	 * keys, so we allocate space for all attributes. That may use more memory
 	 * but it's probably cheaper than determining which attributes are used.
 	 *
+	 * We keep null and regular keys separate, so that we can pass just the
+	 * regular keys to the consistent function easily.
+	 *
 	 * XXX The widest index can have 32 attributes, so the amount of wasted
 	 * memory is negligible. We could invent a more compact approach (with
 	 * just space for used attributes) but that would make the matching more
 	 * complex so it's not a good trade-off.
 	 */
 	keys = palloc0(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts);
+	nullkeys = palloc0(sizeof(ScanKey *) * bdesc->bd_tupdesc->natts);
 	nkeys = palloc0(sizeof(int) * bdesc->bd_tupdesc->natts);
+	nnullkeys = palloc0(sizeof(int) * bdesc->bd_tupdesc->natts);
 
 	/* Preprocess the scan keys - split them into per-attribute arrays. */
 	for (keyno = 0; keyno < scan->numberOfKeys; keyno++)
@@ -444,33 +429,47 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 				TupleDescAttr(bdesc->bd_tupdesc,
 							  keyattno - 1)->attcollation));
 
-		/* First time we see this attribute, so init the array of keys. */
-		if (!keys[keyattno - 1])
+		/*
+		 * First time we see this index attribute, so init as needed.
+		 *
+		 * This is a bit of an overkill - we don't know how many scan keys are
+		 * there for this attribute, so we simply allocate the largest number
+		 * possible (as if all keys were for this attribute). This may waste a
+		 * bit of memory, but we only expect small number of scan keys in
+		 * general, so this should be negligible, and repeated repalloc calls
+		 * are not free either.
+		 */
+		if (consistentFn[keyattno - 1].fn_oid == InvalidOid)
 		{
 			FmgrInfo   *tmp;
 
-			/*
-			 * This is a bit of an overkill - we don't know how many scan keys
-			 * are there for this attribute, so we simply allocate the largest
-			 * number possible (as if all keys were for this attribute). This
-			 * may waste a bit of memory, but we only expect small number of
-			 * scan keys in general, so this should be negligible, and
-			 * repeated repalloc calls are not free either.
-			 */
-			keys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys);
-
-			/* First time this column, so look up consistent function */
-			Assert(consistentFn[keyattno - 1].fn_oid == InvalidOid);
+			/* No key/null arrays for this attribute. */
+			Assert((keys[keyattno - 1] == NULL) && (nkeys[keyattno - 1] == 0));
+			Assert((nullkeys[keyattno - 1] == NULL) && (nnullkeys[keyattno - 1] == 0));
 
 			tmp = index_getprocinfo(idxRel, keyattno,
 									BRIN_PROCNUM_CONSISTENT);
 			fmgr_info_copy(&consistentFn[keyattno - 1], tmp,
 						   CurrentMemoryContext);
 		}
 
-		/* Add key to the per-attribute array. */
-		keys[keyattno - 1][nkeys[keyattno - 1]] = key;
-		nkeys[keyattno - 1]++;
+		/* Add key to the proper per-attribute array. */
+		if (key->sk_flags & SK_ISNULL)
+		{
+			if (!nullkeys[keyattno - 1])
+				nullkeys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys);
+
+			nullkeys[keyattno - 1][nnullkeys[keyattno - 1]] = key;
+			nnullkeys[keyattno - 1]++;
+		}
+		else
+		{
+			if (!keys[keyattno - 1])
+				keys[keyattno - 1] = palloc0(sizeof(ScanKey) * scan->numberOfKeys);
+
+			keys[keyattno - 1][nkeys[keyattno - 1]] = key;
+			nkeys[keyattno - 1]++;
+		}
 	}
 
 	/* allocate an initial in-memory tuple, out of the per-range memcxt */
@@ -549,15 +548,58 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
 					Datum		add;
 					Oid			collation;
 
-					/* skip attributes without any scan keys */
-					if (nkeys[attno - 1] == 0)
+					/*
+					 * skip attributes without any scan keys (both regular and
+					 * IS [NOT] NULL)
+					 */
+					if (nkeys[attno - 1] == 0 && nnullkeys[attno - 1] == 0)
 						continue;
 
 					bval = &dtup->bt_columns[attno - 1];
 
+					/*
+					 * First check if there are any IS [NOT] NULL scan keys,
+					 * and if we're violating them. In that case we can
+					 * terminate early, without invoking the support function.
+					 *
+					 * As there may be more keys, we can only detemine
+					 * mismatch within this loop.
+					 */
+					if (bdesc->bd_info[attno - 1]->oi_regular_nulls &&
+						!check_null_keys(bval, nullkeys[attno - 1],
+										 nnullkeys[attno - 1]))
+					{
+						/*
+						 * If any of the IS [NOT] NULL keys failed, the page
+						 * range as a whole can't pass. So terminate the loop.
+						 */
+						addrange = false;
+						break;
+					}
+
+					/*
+					 * So either there are no IS [NOT] NULL keys, or all
+					 * passed. If there are no regular scan keys, we're done -
+					 * the page range matches. If there are regular keys, but
+					 * the page range is marked as 'all nulls' it can't
+					 * possibly pass (we're assuming the operators are
+					 * strict).
+					 */
+
+					/* No regular scan keys - page range as a whole passes. */
+					if (!nkeys[attno - 1])
+						continue;
+
 					Assert((nkeys[attno - 1] > 0) &&
 						   (nkeys[attno - 1] <= scan->numberOfKeys));
 
+					/* If it is all nulls, it cannot possibly be consistent. */
+					if (bval->bv_allnulls)
+					{
+						addrange = false;
+						break;
+					}
+
 					/*
 					 * Check whether the scan key is consistent with the page
 					 * range values; if so, have the pages in the range added
@@ -663,7 +705,6 @@ brinbuildCallback(Relation index,
 {
 	BrinBuildState *state = (BrinBuildState *) brstate;
 	BlockNumber thisblock;
-	int			i;
 
 	thisblock = ItemPointerGetBlockNumber(tid);
 
@@ -692,25 +733,8 @@ brinbuildCallback(Relation index,
 	}
 
 	/* Accumulate the current tuple into the running state */
-	for (i = 0; i < state->bs_bdesc->bd_tupdesc->natts; i++)
-	{
-		FmgrInfo   *addValue;
-		BrinValues *col;
-		Form_pg_attribute attr = TupleDescAttr(state->bs_bdesc->bd_tupdesc, i);
-
-		col = &state->bs_dtuple->bt_columns[i];
-		addValue = index_getprocinfo(index, i + 1,
-									 BRIN_PROCNUM_ADDVALUE);
-
-		/*
-		 * Update dtuple state, if and as necessary.
-		 */
-		FunctionCall4Coll(addValue,
-						  attr->attcollation,
-						  PointerGetDatum(state->bs_bdesc),
-						  PointerGetDatum(col),
-						  values[i], isnull[i]);
-	}
+	(void) add_values_to_range(index, state->bs_bdesc, state->bs_dtuple,
+							   values, isnull);
 }
 
 /*
@@ -1489,6 +1513,39 @@ union_tuples(BrinDesc *bdesc, BrinMemTuple *a, BrinTuple *b)
 		FmgrInfo   *unionFn;
 		BrinValues *col_a = &a->bt_columns[keyno];
 		BrinValues *col_b = &db->bt_columns[keyno];
+		BrinOpcInfo *opcinfo = bdesc->bd_info[keyno];
+
+		if (opcinfo->oi_regular_nulls)
+		{
+			/* 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)
+				continue;
+
+			/*
+			 * 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)
+			{
+				int			i;
+
+				col_a->bv_allnulls = false;
+
+				for (i = 0; i < opcinfo->oi_nstored; i++)
+					col_a->bv_values[i] =
+						datumCopy(col_b->bv_values[i],
+								  opcinfo->oi_typcache[i]->typbyval,
+								  opcinfo->oi_typcache[i]->typlen);
+
+				continue;
+			}
+		}
 
 		unionFn = index_getprocinfo(bdesc->bd_index, keyno + 1,
 									BRIN_PROCNUM_UNION);
@@ -1542,3 +1599,103 @@ brin_vacuum_scan(Relation idxrel, BufferAccessStrategy strategy)
 	 */
 	FreeSpaceMapVacuum(idxrel);
 }
+
+static bool
+add_values_to_range(Relation idxRel, BrinDesc *bdesc, BrinMemTuple *dtup,
+					Datum *values, bool *nulls)
+{
+	int			keyno;
+	bool		modified = false;
+
+	/*
+	 * Compare the key values of the new tuple to the stored index values; our
+	 * deformed tuple will get updated if the new tuple doesn't fit the
+	 * original range (note this means we can't break out of the loop early).
+	 * Make a note of whether this happens, so that we know to insert the
+	 * modified tuple later.
+	 */
+	for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
+	{
+		Datum		result;
+		BrinValues *bval;
+		FmgrInfo   *addValue;
+
+		bval = &dtup->bt_columns[keyno];
+
+		if (bdesc->bd_info[keyno]->oi_regular_nulls && nulls[keyno])
+		{
+			/*
+			 * 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 (!bval->bv_hasnulls)
+			{
+				bval->bv_hasnulls = true;
+				modified = true;
+			}
+
+			continue;
+		}
+
+		addValue = index_getprocinfo(idxRel, keyno + 1,
+									 BRIN_PROCNUM_ADDVALUE);
+		result = FunctionCall4Coll(addValue,
+								   idxRel->rd_indcollation[keyno],
+								   PointerGetDatum(bdesc),
+								   PointerGetDatum(bval),
+								   values[keyno],
+								   nulls[keyno]);
+		/* if that returned true, we need to insert the updated tuple */
+		modified |= DatumGetBool(result);
+	}
+
+	return modified;
+}
+
+static bool
+check_null_keys(BrinValues *bval, ScanKey *nullkeys, int nnullkeys)
+{
+	int			keyno;
+
+	/*
+	 * First check if there are any IS [NOT] NULL scan keys, and if we're
+	 * violating them.
+	 */
+	for (keyno = 0; keyno < nnullkeys; keyno++)
+	{
+		ScanKey		key = nullkeys[keyno];
+
+		Assert(key->sk_attno == bval->bv_attno);
+
+		/* Handle only IS NULL/IS NOT NULL tests */
+		if (!(key->sk_flags & SK_ISNULL))
+			continue;
+
+		if (key->sk_flags & SK_SEARCHNULL)
+		{
+			/* IS NULL scan key, but range has no NULLs */
+			if (!bval->bv_allnulls && !bval->bv_hasnulls)
+				return false;
+		}
+		else if (key->sk_flags & SK_SEARCHNOTNULL)
+		{
+			/*
+			 * For IS NOT NULL, we can only skip ranges that are known to have
+			 * only nulls.
+			 */
+			if (bval->bv_allnulls)
+				return false;
+		}
+		else
+		{
+			/*
+			 * Neither IS NULL nor IS NOT NULL was used; assume all indexable
+			 * operators are strict and thus return false with NULL value in
+			 * the scan key.
+			 */
+			return false;
+		}
+	}
+
+	return true;
+}