Mihail Nikalayeu <[email protected]> wrote: > PART 1: > > -------------- > > Something still wrong with 0006, check: > > 'pgbench: error: client 12 script 0 aborted in command 2 query 0: ERROR: > attempted to overwrite invisible tuple > https://cirrus-ci.com/task/6385612527239168?logs=test_world#L300 > > But it is hard to reproduce - happened once. > > -------------- > > Also, once I got > [16:25:18.641] # at > /tmp/cirrus-ci-build/contrib/amcheck/t/007_repack_concurrently.pl line 57. > [16:25:18.641] # 'pgbench: error: client 6 script 0 aborted > in command 2 query 0: ERROR: relation 21856 deleted while still in use > https://cirrus-ci.com/task/4686014242881536?logs=test_world#L384 > > It was the PROC_IN_REPACK version (see below), but I think it is not related > to it. But I'm not 100% sure.
I think it *is* related. My earlier patch version, which used the PROC_IN_VACUUM flag improperly [1] was also causing visibility issues. Please let me know if you manage to reproduce the issue with v32. > PART 2: > > > I'm considering a special kind of relation whose catalog entries remain in > > the > > catalog cache and are never written to the catalog tables. (Unlike > > temporary > > relation, it'd be WAL logged so that REPACK can be replayed on standby.) > > I think it is too complicated, especially including replication logic. I'm confused by hearing a complaint about complexity of code that I haven't posted yet. And I don't understand the relationship to "replication logic": REPACK (CONCURRENTLY) tries to avoid decoding of data changes in the *new* (transient) relation anyway. > Essentially we have two issues: > 1) make sure catalog entities are not dropped because the vacuum > 2) make sure data in new table is not vacuumed also 3) XID assigned early due to creation of catalog entries for the new table - that XID prevents the VACUUM xmin horizon from advancing till the end of the transaction, i.e. till the end of REPACK execution. > Also, I am still not sure if MVCC-safe implementation is worth its complexity > compared with "relcheckxmin"approach [0]. IMO it's better for users to see the correct data than ERROR. But it still needs work. [1] https://www.postgresql.org/message-id/88003.1769511456%40localhost -- Antonin Houska Web: https://www.cybertec-postgresql.com
