Re: In-placre persistance change of a relation

At Tue, 21 Dec 2021 17:13:21 +0900 (JST), Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> wrote in
> Ugh! I completely forgot about TAP tests.. Thanks for the testing and
> sorry for the bugs.
>
> This is a bit big change so I need a bit of time before posting the
> next version.

I took a bit too long detour but the patch gets to pass make-world for
me.

In this version:

- When relation persistence is changed from logged to unlogged, buffer
persistence is flipped then an init-fork is created along with a mark
file for the fork (RelationCreateInitFork). The mark file is removed
at commit but left alone after a crash before commit. At the next
startup, ResetUnloggedRelationsInDbspaceDir() removes the init fork
file if it finds the mark file corresponding to the file.

- When relation persistence is changed from unlogged to logged, buffer
persistence is flipped then the exisging init-fork is marked to be
dropped at commit (RelationDropInitFork). Finally the whole content
is WAL-logged in the page-wise manner (RelationChangePersistence),

- The two operations above are repeatable within a transaction and
commit makes the last operation persist and rollback make the all
operations abandoned.

- Storage files are created along with a "mark" file for the
relfilenode. It behaves the same way to the above except the mark
files corresponds to the whole relfilenode.

- The at-commit operations this patch adds require to be WAL-logged so
they don't fit pendingDeletes list, which is executed after commit. I
added a new pending-work list pendingCleanups that is executed just
after pendingSyncs. (new in this version)

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center