From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Wed, 16 Dec 2020 23:57:11 +0100
Subject: [PATCH 6/8] add sort_mode opclass parameter

---
 src/backend/access/brin/brin_bloom.c | 34 ++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/src/backend/access/brin/brin_bloom.c b/src/backend/access/brin/brin_bloom.c
index ffeb459d3e..ac5a5c249c 100644
--- a/src/backend/access/brin/brin_bloom.c
+++ b/src/backend/access/brin/brin_bloom.c
@@ -180,6 +180,7 @@ typedef struct BloomOptions
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	double		nDistinctPerRange;	/* number of distinct values per range */
 	double		falsePositiveRate;	/* false positive for bloom filter */
+	bool		sortMode;			/* start in sort mode */
 } BloomOptions;
 
 /*
@@ -216,6 +217,7 @@ typedef struct BloomOptions
 #define		BLOOM_MIN_FALSE_POSITIVE_RATE	0.0001		/* 0.01% fp rate */
 #define		BLOOM_MAX_FALSE_POSITIVE_RATE	0.25		/* 25% fp rate */
 #define		BLOOM_DEFAULT_FALSE_POSITIVE_RATE	0.01	/* 1% fp rate */
+#define		BLOOM_DEFAULT_SORT_MODE			true		/* start in sort */
 
 #define BloomGetNDistinctPerRange(opts) \
 	((opts) && (((BloomOptions *) (opts))->nDistinctPerRange != 0) ? \
@@ -227,6 +229,10 @@ typedef struct BloomOptions
 	 (((BloomOptions *) (opts))->falsePositiveRate) : \
 	 BLOOM_DEFAULT_FALSE_POSITIVE_RATE)
 
+#define BloomGetSortMode(opts) \
+	((opts) ? (((BloomOptions *) (opts))->sortMode) : \
+	 BLOOM_DEFAULT_SORT_MODE)
+
 /*
  * Bloom Filter
  *
@@ -302,7 +308,7 @@ static BloomFilter *bloom_switch_to_hashing(BloomFilter *filter);
  * varlena.
  */
 static BloomFilter *
-bloom_init(int ndistinct, double false_positive_rate)
+bloom_init(bool sort_mode, int ndistinct, double false_positive_rate)
 {
 	Size			len;
 	BloomFilter	   *filter;
@@ -336,17 +342,26 @@ bloom_init(int ndistinct, double false_positive_rate)
 	k = (k - floor(k) >= 0.5) ? ceil(k) : floor(k);
 
 	/*
-	 * Allocate the bloom filter (initially it's just a header, we'll make
-	 * it larger as needed).
+	 * When sort phase is enabled, allocate just the header - we'll make
+	 * it larger as needed. In hash mode we allocate the whole filter.
+	 *
+	 * XXX We might add some sort of sparse bitmap, which might work for
+	 * bloom filters with only a couple items.
 	 */
-	len = offsetof(BloomFilter, data);
+	if (sort_mode)
+		len = offsetof(BloomFilter, data);
+	else
+		len = offsetof(BloomFilter, data) + (m / 8);
 
 	filter = (BloomFilter *) palloc0(len);
 
-	filter->flags = 0;	/* implies SORTED phase */
+	filter->flags = 0;
 	filter->nhashes = (int) k;
 	filter->nbits = m;
 
+	if (!sort_mode)
+		filter->flags |= BLOOM_FLAG_PHASE_HASH;
+
 	SET_VARSIZE(filter, len);
 
 	return filter;
@@ -757,7 +772,6 @@ brin_bloom_get_ndistinct(BrinDesc *bdesc, BloomOptions *opts)
 	return (int) ndistinct;
 }
 
-
 /*
  * Examine the given index tuple (which contains partial status of a certain
  * page range) by comparing it to the given value that comes from another heap
@@ -790,7 +804,8 @@ brin_bloom_add_value(PG_FUNCTION_ARGS)
 	 */
 	if (column->bv_allnulls)
 	{
-		filter = bloom_init(brin_bloom_get_ndistinct(bdesc, opts),
+		filter = bloom_init(BloomGetSortMode(opts),
+							brin_bloom_get_ndistinct(bdesc, opts),
 							BloomGetFalsePositiveRate(opts));
 		column->bv_values[0] = PointerGetDatum(filter);
 		column->bv_allnulls = false;
@@ -1022,6 +1037,11 @@ brin_bloom_options(PG_FUNCTION_ARGS)
 							 BLOOM_MAX_FALSE_POSITIVE_RATE,
 							 offsetof(BloomOptions, falsePositiveRate));
 
+	add_local_bool_reloption(relopts, "sort_mode",
+							 "start the bloom filter in sort mode",
+							 BLOOM_DEFAULT_SORT_MODE,
+							 offsetof(BloomOptions, sortMode));
+
 	PG_RETURN_VOID();
 }
 
-- 
2.26.2


--------------CF71AF65F7C337C37C24B045
Content-Type: text/x-patch; charset=UTF-8;
 name="0007-BRIN-minmax-multi-indexes-20210112.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename="0007-BRIN-minmax-multi-indexes-20210112.patch"