On Thu, May 23, 2019 at 8:08 AM Amit Khandekar <amitdkhan...@gmail.com> wrote: > This made me think more of the race conditions. For instance, in > pg_create_logical_replication_slot(), just after > CheckLogicalDecodingRequirements and before actually creating the > slot, suppose concurrently Controlfile->wal_level is changed from > logical to replica. So suppose a new slot does get created. Later the > slot is read, so in pg_logical_slot_get_changes_guts(), > CheckLogicalDecodingRequirements() is called where it checks > ControlFile->wal_level value. But just before it does that, > ControlFile->wal_level concurrently changes back to logical, because > of replay of another param-change record. So this logical reader will > think that the wal_level is sufficient, and will proceed to read the > records, but those records are *before* the wal_level change, so these > records don't have logical data. > > Do you think this is possible, or I am missing something?
wal_level is PGC_POSTMASTER. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
