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commit    3cd4135119be0dda37ef810353a3ef2e4444970e
Author:   Tomas Vondra <tomas.vondra@postgresql.org>
Date:     Sun Apr 14 15:58:59 2024 +0000
First released in: 17.0, 14.12, 15.7, 16.3

    Update nbits_set in brin_bloom_union
    
    Properly update the number of bits set in the bitmap after merging the
    filters in brin_bloom_union.
    
    This is mostly harmless, as the counter is used only in the output
    function, which means pageinspect may show incorrect information about
    the BRIN summary. The counter does not affect correctness.
    
    Discovered while adding a regression test comparing indexes built with
    and without parallelism. The parallel index builds exercise the union
    procedure when merging results from workers, which is otherwise very
    hard to do in a test. Which is why this went unnoticed until now.
    
    Backpatch through 14, where the BRIN bloom opclasses were introduced.
    
    Backpatch-through: 14
    Discussion: https://postgr.es/m/1df00a66-db5a-4e66-809a-99b386a06d86%40enterprisedb.com


 src/backend/access/brin/brin_bloom.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/backend/access/brin/brin_bloom.c b/src/backend/access/brin/brin_bloom.c
index 23de868d3df..c0407e5816b 100644
--- a/src/backend/access/brin/brin_bloom.c
+++ b/src/backend/access/brin/brin_bloom.c
@@ -660,6 +660,9 @@ brin_bloom_union(PG_FUNCTION_ARGS)
 	for (i = 0; i < nbytes; i++)
 		filter_a->data[i] |= filter_b->data[i];
 
+	/* update the number of bits set in the filter */
+	filter_a->nbits_set = pg_popcount((const char *) filter_a->data, nbytes);
+
 	PG_RETURN_VOID();
 }
 


[parent: 7c490a18b75b]