Thread

[PATCH] Improve REPACK (CONCURRENTLY) error messages for unsupported configurations

Baji Shaik <baji.pgdev@gmail.com> — 2026-05-27T03:06:13Z

Hi,

While exploring the new REPACK (CONCURRENTLY) feature, I noticed
a few user-facing error paths that could be made more accurate.
Patch series of three:

 0001 -- When wal_level < replica, REPACK (CONCURRENTLY) currently
         surfaces generic "replication slots ... wal_level" error
         from CheckSlotRequirements(), with a CONTEXT line referring
         to an internal worker.  Add an upfront check that reports a
         REPACK-specific error.

 0002 -- check_concurrent_repack_requirements() reports the same
         generic "no identity index" error for several distinct
         cases, two of which are misleading: REPLICA IDENTITY FULL
         (which is set, but the hint says there is no identity), and
         a deferrable PK as the only identity (skipped per commit
         832e220d99a, but the hint suggests adding an index that
         already exists).  Distinguish these cases.

 0003 -- Four ereport(ERROR) calls in the REPACK CONCURRENTLY code
         path lack errcode() and default to ERRCODE_INTERNAL_ERROR.
         Add appropriate errcodes; in particular, the
         apply_concurrent_update/delete failures map cleanly to
         ERRCODE_T_R_SERIALIZATION_FAILURE.

All three are error-path only; the success path is unchanged.  Each
patch is independently committable.  Detailed rationale is in the
individual commit messages.

Tested with `make check` (245/245 pass) and `make isolation/check`
(128/128 pass) on top of master; 0002 also updates
src/test/regress/expected/cluster.out to match the new deferrable-PK
message.

Thanks,
Baji Shaik