Re: Hot standby, recovery infra

Simon Riggs wrote:
> My proposed fix for Fujii-san's minSafeStartPoint bug is to introduce
> another control file state DB_IN_ARCHIVE_RECOVERY_BASE. This would show
> that we are still recovering up to the point of the end of the base
> backup. Once we reach minSafeStartPoint we then switch state to
> DB_IN_ARCHIVE_RECOVERY, and set baseBackupReached boolean, which then
> enables writing new minSafeStartPoints when we open new WAL files in the
> future.

I don't see how that helps, the bug has nothing to with base backups. It
comes from the fact that we set minSafeStartPoint beyond the actual end
of WAL, if the last WAL segment is only partially filled (= fails CRC
check at some point). If we crash after setting minSafeStartPoint like
that, and then restart recovery, we'll get the error.

The last WAL segment could be partially filled for example because the
DBA has manually copied the last unarchived WAL segments to pg_xlog, as
we recommend in the manual.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com