Re: Re: BUG #12990: Missing pg_multixact/members files (appears to have wrapped, then truncated)

On Tue, Apr 28, 2015 at 2:23 AM, Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:
> Ah, yeah, we do want the full range; that's already built in the code
> elsewhere.
>
> In this version, I used your WouldWrap function, but there was a bug in
> your formulation of the call site: after the WARNING has been issued
> once, it is never issued again for that wraparound cycle, because the
> second time around the nextOffset has already crossed the boundary and
> your routine returns false.  IMO this is wrong and the warning should be
> issued every time.  To fix that problem I removed the offsetWarnLimit
> altogether, and instead do WouldWrap() of the value against
> offsetStopLimit minus the 20 segments.  That way, the warning is issued
> continuously until the offsetStopLimit is reached (once there,
> obviously, only the error is thrown, not the warning, which is correct.)
>
> I also added a call to DetermineSafeOldestOffset() in TrimMultiXact:
> as far as I can tell, this is necessary for the time when a standby
> exits recovery, because when InRecovery we return early from
> DetermineSafeOldestOffset() so the safe point would never get set.

Putting the period inside the parentheses here looks weird?

+                                  "This command would create a
multixact with %u members, which exceeds remaining space (%u
members.)",

Maybe rephrase as: "This command would create a multixact with %u
members, but the remaining space is only enough for %u members."

I don't think this should have a comma:

+                 errhint("Execute a database-wide VACUUM in that
database, with reduced vacuum_multixact_freeze_min_age and
vacuum_multixact_freeze_table_age settings.")));

This looks like excess brace-ifiaction:

+    if (start < boundary)
+    {
+        return finish >= boundary || finish < start;
+    }
+    else
+    {
+        return finish >= boundary && finish < start;
+    }

I think this is confusing:


--
Robert Haas
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