Skip WAL for unlogged main fork during online checksum enable ProcessSingleRelationFork() unconditionally generated an FPI WAL record for every page of every relation when enabling checksums. Unlogged relations, which by definition never generate WAL for data changes, were not exempt which generated excessive WAL to be emitted.
Fix by guarding the FPI WAL record call with RelationNeedsWAL() to avoid emitting WAL for unlogged main forks. Unlogged pages are still dirtied to ensure the checksum is written to disk at the next checkpoint. The init fork remains WAL-logged even for unlogged relations, as it's needed on the standby to materialize the relation after promotion (see ResetUnloggedRelations()). Skipping init-fork WAL would leave the standby with a stale init fork that, once copied to the main fork on promotion, would fail checksum verification on every read of the unlogged relation. A test which creates an unlogged table with an index, enables checksums, promotes the standby, and verifies that the unlogged relation and its indexes are still readable post-promotion has been added. Author: Satyanarayana Narlapuram <[email protected]> Reviewed-by: Daniel Gustafsson <[email protected]> Reviewed-by: Ayush Tiwari <[email protected]> Discussion: https://postgr.es/m/cahg+qdegrpzbnzdljd_t4b43xkeexzn0hghkfm-1bkbdyzk...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/2018bd6167909f3de7405774527d1230397950e0 Modified Files -------------- src/backend/postmaster/datachecksum_state.c | 15 ++- .../test_checksums/t/003_standby_restarts.pl | 111 ++++++++++++++++++++- 2 files changed, 123 insertions(+), 3 deletions(-)
