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Data loss can happen when the DDLs like ALTER PUBLICATION ... ADD TABLE ... or ALTER TYPE ... that don't take a strong lock on table happens concurrently to DMLs on the tables involved in the DDL. This happens because logical decoding doesn't distribute invalidations to concurrent transactions and those transactions use stale cache data to decode the changes. The problem becomes bigger because we keep using the stale cache even after those in-progress transactions are finished and skip the changes required to be sent to the client. This commit fixes the issue by distributing invalidation messages from catalog-modifying transactions to all concurrent in-progress transactions. This allows the necessary rebuild of the catalog cache when decoding new changes after concurrent DDL. We observed performance regression primarily during frequent execution of *publication DDL* statements that modify the published tables. The regression is minor or nearly nonexistent for DDLs that do not affect the published tables or occur infrequently, making this a worthwhile cost to resolve a longstanding data loss issue. An alternative approach considered was to take a strong lock on each affected table during publication modification. However, this would only address issues related to publication DDLs (but not the ALTER TYPE ...) and require locking every relation in the database for publications created as FOR ALL TABLES, which is impractical. The bug exists in all supported branches, but we are backpatching till 14. The fix for 13 requires somewhat bigger changes than this fix, so the fix for that branch is still under discussion. Reported-by: hubert depesz lubaczewski <depesz@depesz.com> Reported-by: Tomas Vondra <tomas.vondra@enterprisedb.com> Author: Shlok Kyal <shlok.kyal.oss@gmail.com> Author: Hayato Kuroda <kuroda.hayato@fujitsu.com> Reviewed-by: Zhijie Hou <houzj.fnst@fujitsu.com> Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Tested-by: Benoit Lobréau <benoit.lobreau@dalibo.com> Backpatch-through: 14 Discussion: https://postgr.es/m/de52b282-1166-1180-45a2-8d8917ca74c6@enterprisedb.com Discussion: https://postgr.es/m/CAD21AoAenVqiMjpN-PvGHL1N9DWnHSq673bfgr6phmBUzx=kLQ@mail.gmail.com
39 lines
1.4 KiB
Makefile
39 lines
1.4 KiB
Makefile
# contrib/test_decoding/Makefile
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MODULES = test_decoding
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PGFILEDESC = "test_decoding - example of a logical decoding output plugin"
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REGRESS = ddl xact rewrite toast permissions decoding_in_xact \
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decoding_into_rel binary prepared replorigin time messages \
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spill slot truncate stream stats twophase twophase_stream
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ISOLATION = mxact delayed_startup ondisk_startup concurrent_ddl_dml \
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oldest_xmin snapshot_transfer subxact_without_top concurrent_stream \
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twophase_snapshot slot_creation_error catalog_change_snapshot \
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skip_snapshot_restore invalidation_distrubution
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REGRESS_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
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ISOLATION_OPTS = --temp-config $(top_srcdir)/contrib/test_decoding/logical.conf
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# Disabled because these tests require "wal_level=logical", which
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# typical installcheck users do not have (e.g. buildfarm clients).
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NO_INSTALLCHECK = 1
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TAP_TESTS = 1
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ifdef USE_PGXS
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PG_CONFIG = pg_config
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PGXS := $(shell $(PG_CONFIG) --pgxs)
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include $(PGXS)
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else
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subdir = contrib/test_decoding
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global
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include $(top_srcdir)/contrib/contrib-global.mk
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endif
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# But it can nonetheless be very helpful to run tests on preexisting
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# installation, allow to do so, but only if requested explicitly.
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installcheck-force:
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$(pg_regress_installcheck) $(REGRESS)
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$(pg_isolation_regress_installcheck) $(ISOLATION)
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