From b511d7323df605fbb97ac8f158801cf53b028e41 Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Thu, 18 May 2023 13:00:31 +0200 Subject: [PATCH] Fix handling of NULLs when merging BRIN summaries When merging BRIN summaries, union_tuples() did not correctly update the target hasnulls/allnulls flags. When merging all-NULL summary into a summary without any NULL values, the result had both flags set to false (instead of having hasnulls=true). This happened because the code only considered the hasnulls flags, ignoring the possibility the source summary has allnulls=true. Discovered while investigating issues with handling empty BRIN ranges and handling of NULL values, but it's a separate problem (has nothing to do with empty ranges). Fixed by considering both flags on the source summary, and updating the hasnulls flag on the target summary. Backpatch to 11. The bug exists since 9.5 (where BRIN indexes were introduced), but those releases are EOL already. Discussion: https://postgr.es/m/9d993d0d-e431-2196-9ccc-0554d0e60154%40enterprisedb.com --- src/backend/access/brin/brin_inclusion.c | 10 +++++++++- src/backend/access/brin/brin_minmax.c | 10 +++++++++- 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/src/backend/access/brin/brin_inclusion.c b/src/backend/access/brin/brin_inclusion.c index e063f40b37..adb2439df7 100644 --- a/src/backend/access/brin/brin_inclusion.c +++ b/src/backend/access/brin/brin_inclusion.c @@ -515,10 +515,13 @@ brin_inclusion_union(PG_FUNCTION_ARGS) FmgrInfo *finfo; Datum result; + /* Does the "b" summary represent any NULL values? */ + bool b_has_nulls = (col_b->bv_hasnulls || col_b->bv_allnulls); + Assert(col_a->bv_attno == col_b->bv_attno); /* Adjust "hasnulls". */ - if (!col_a->bv_hasnulls && col_b->bv_hasnulls) + if (!col_a->bv_allnulls && b_has_nulls) col_a->bv_hasnulls = true; /* If there are no values in B, there's nothing left to do. */ @@ -533,10 +536,15 @@ brin_inclusion_union(PG_FUNCTION_ARGS) * 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. + * + * Also adjust "hasnulls" in order not to forget the summary represents NULL + * values. This is not redundant with the earlier update, because that only + * happens when allnulls=false. */ if (col_a->bv_allnulls) { col_a->bv_allnulls = false; + col_a->bv_hasnulls = true; col_a->bv_values[INCLUSION_UNION] = datumCopy(col_b->bv_values[INCLUSION_UNION], attr->attbyval, attr->attlen); diff --git a/src/backend/access/brin/brin_minmax.c b/src/backend/access/brin/brin_minmax.c index 0f6aa33a45..8fb25fc494 100644 --- a/src/backend/access/brin/brin_minmax.c +++ b/src/backend/access/brin/brin_minmax.c @@ -249,10 +249,13 @@ brin_minmax_union(PG_FUNCTION_ARGS) FmgrInfo *finfo; bool needsadj; + /* Does the "b" summary represent any NULL values? */ + bool b_has_nulls = (col_b->bv_hasnulls || col_b->bv_allnulls); + Assert(col_a->bv_attno == col_b->bv_attno); /* Adjust "hasnulls" */ - if (!col_a->bv_hasnulls && col_b->bv_hasnulls) + if (!col_a->bv_allnulls && b_has_nulls) col_a->bv_hasnulls = true; /* If there are no values in B, there's nothing left to do */ @@ -267,10 +270,15 @@ brin_minmax_union(PG_FUNCTION_ARGS) * 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. + * + * Also adjust "hasnulls" in order not to forget the summary represents NULL + * values. This is not redundant with the earlier update, because that only + * happens when allnulls=false. */ if (col_a->bv_allnulls) { col_a->bv_allnulls = false; + col_a->bv_hasnulls = true; 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],