Release memory allocated by dependency_degree
Calculating degree of a functional dependency may allocate a lot of
memory - we have released mot of the explicitly allocated memory, but
e.g. detoasted varlena values were left behind. That may be an issue,
because we consider a lot of dependencies (all combinations), and the
detoasting may happen for each one again.
Fixed by calling dependency_degree() in a dedicated context, and
resetting it after each call. We only need the calculated dependency
degree, so we don't need to copy anything.
Backpatch to PostgreSQL 10, where extended statistics were introduced.
Backpatch-through: 10
Discussion: https://www.postgresql.org/message-id/20210915200928.GP831%40telsasoft.com
Branch
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REL_11_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/4487a7def3ae6efa79c545c3edc03ea97f446e36
Modified Files
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src/backend/statistics/dependencies.c | 22 +++++++++++++++++-----
1 file changed, 17 insertions(+), 5 deletions(-)