Re: Re: [COMMITTERS] pgsql: Assorted cleanups in preparation for using a map file to support

Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On Wed, 2010-02-03 at 10:48 -0500, Tom Lane wrote:
>>> If so, there is some minor code cleanup and comment changes in
>>> ProcessCommittedInvalidationMessages(). Would you like me to do that, or
>>> should we wait?
>>
>> I saw that. I didn't touch it because it's not directly relevant to
>> what I'm doing right now, but I would like to go back and see whether
>> that routine can't be got rid of completely. It seems to me to be a
>> very klugy substitute for having enough information. I'm inclined to
>> think that we should emit an sinval message (or maybe better a separate
>> WAL entry) for initfile removal, instead of trying to reverse-engineer
>> whether one happened.

> An additional sinval message type would work. There is a requirement for
> us to run RelationCacheInitFileInvalidate() both before and after the
> other messages. So we would need to append and prepend the new message
> type onto the array of messages if transInvalInfo->RelcacheInitFileInval
> is true. That way we would just do SendSharedInvalidMessages() in
> xact_redo_commit and remove ProcessCommittedInvalidationMessages(),
> adding other code to handle the inval message. Doesn't seem any easier
> though.

> Another WAL record would definitely be cumbersome.

BTW, we're definitely going to have to do *something* with that code,
because it's assuming that non-shared relcache init files always live in
DEFAULTTABLESPACE. That is not correct. I think that there is no
simple way for the startup process to identify which tablespace a given
database lives in (normally, one would have to consult pg_database to
find that out). So we are going to have to drive this off an sinval or
WAL record that does provide the tablespace as well as the DB OID.

regards, tom lane