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pgsql: Avoid caching expression state trees for domain constraints acro 2+ messages / 1 participants [nested] [flat]
* pgsql: Avoid caching expression state trees for domain constraints acro @ 2015-11-29 23:18 Tom Lane <tgl@sss.pgh.pa.us> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2015-11-29 23:18 UTC (permalink / raw) To: pgsql-committers Avoid caching expression state trees for domain constraints across queries. In commit 8abb3cda0ddc00a0ab98977a1633a95b97068d4e I attempted to cache the expression state trees constructed for domain CHECK constraints for the life of the backend (assuming the domain's constraints don't get redefined). However, this turns out not to work very well, because execQual.c will run those state trees with ecxt_per_query_memory pointing to a query-lifespan context, and in some situations we'll end up with pointers into that context getting stored into the state trees. This happens in particular with SQL-language functions, as reported by Emre Hasegeli, but there are many other cases. To fix, keep only the expression plan trees for domain CHECK constraints in the typcache's data structure, and revert to performing ExecInitExpr (at least) once per query to set up expression state trees in the query's context. Eventually it'd be nice to undo this, but that will require some careful thought about memory management for expression state trees, and it seems far too late for any such redesign in 9.5. This way is still much more efficient than what happened before 8abb3cda0. Branch ------ master Details ------- http://git.postgresql.org/pg/commitdiff/ec7eef6b1103f92aea94aa79aabd8e0e87973010 Modified Files -------------- src/backend/utils/cache/typcache.c | 62 +++++++++++++++++++++++++++++++--- src/include/utils/typcache.h | 1 + src/test/regress/expected/domain.out | 25 ++++++++++++++ src/test/regress/sql/domain.sql | 24 +++++++++++++ 4 files changed, 108 insertions(+), 4 deletions(-) -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers ^ permalink raw reply [nested|flat] 2+ messages in thread
* pgsql: Avoid caching expression state trees for domain constraints acro @ 2015-11-29 23:18 Tom Lane <tgl@sss.pgh.pa.us> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2015-11-29 23:18 UTC (permalink / raw) To: pgsql-committers Avoid caching expression state trees for domain constraints across queries. In commit 8abb3cda0ddc00a0ab98977a1633a95b97068d4e I attempted to cache the expression state trees constructed for domain CHECK constraints for the life of the backend (assuming the domain's constraints don't get redefined). However, this turns out not to work very well, because execQual.c will run those state trees with ecxt_per_query_memory pointing to a query-lifespan context, and in some situations we'll end up with pointers into that context getting stored into the state trees. This happens in particular with SQL-language functions, as reported by Emre Hasegeli, but there are many other cases. To fix, keep only the expression plan trees for domain CHECK constraints in the typcache's data structure, and revert to performing ExecInitExpr (at least) once per query to set up expression state trees in the query's context. Eventually it'd be nice to undo this, but that will require some careful thought about memory management for expression state trees, and it seems far too late for any such redesign in 9.5. This way is still much more efficient than what happened before 8abb3cda0. Branch ------ REL9_5_STABLE Details ------- http://git.postgresql.org/pg/commitdiff/e69d3a82e46461da4c3878487fb99c1294fb1d8f Modified Files -------------- src/backend/utils/cache/typcache.c | 62 +++++++++++++++++++++++++++++++--- src/include/utils/typcache.h | 1 + src/test/regress/expected/domain.out | 25 ++++++++++++++ src/test/regress/sql/domain.sql | 24 +++++++++++++ 4 files changed, 108 insertions(+), 4 deletions(-) -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2015-11-29 23:18 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2015-11-29 23:18 pgsql: Avoid caching expression state trees for domain constraints acro Tom Lane <tgl@sss.pgh.pa.us> 2015-11-29 23:18 pgsql: Avoid caching expression state trees for domain constraints acro Tom Lane <tgl@sss.pgh.pa.us>
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