Re: POC: Cleaning up orphaned files using undo logs

On Wed, May 1, 2019 at 6:02 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
> Replying to myself to resend to the list, since my previous attempt
> seems to have been eaten by a grue.
>
> On Tue, Apr 30, 2019 at 11:14 AM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> >
> > On Tue, Apr 30, 2019 at 2:16 AM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
> > > Like previous version these patch set also applies on:
> > > https://github.com/EnterpriseDB/zheap/tree/undo
> > > (b397d96176879ed5b09cf7322b8d6f2edd8043a5)
> >
> > Some more review of 0003:
> >

Another suggestion:

+/*
+ * Insert a previously-prepared undo records. This will write the actual undo
+ * record into the buffers already pinned and locked in PreparedUndoInsert,
+ * and mark them dirty. This step should be performed after entering a
+ * criticalsection; it should never fail.
+ */
+void
+InsertPreparedUndo(void)
+{
..
..
+
+ /* Advance the insert pointer past this record. */
+ UndoLogAdvance(urp, size);
+ }
..
}

UndoLogAdvance internally takes LWLock and we don't recommend doing
that in the critical section which will happen as this function is
supposed to be invoked in the critical section as mentioned in
comments.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com