Re: Vacuum now uses AccessShareLock for analyze

> its what I suspected, but my point was that if we did the ANALYZE for the
> relation right after the VACUUM for it, there would be a period of time
> where readers could come in and process ... think of it as a 'breather'
> before the next VACUUM starts, vs just jumping into the next ...
> 
> Overall time for doing the vacuum shouldn't be any longer, but it would
> give gaps where readers could get in and out ... we're a relational
> database, so I imagine ppl are doing JOINs ... if RelationA is locked
> while ReaderA is trying to doign a JOIN between RA and RB, ReaderA is
> gonna be screwed ... if we did a quick ANALZE between RelationA and
> RelationB, then ReaderA would have a chance to do its processing while the
> ANALYZE is running, instead of having to wait for both RelationA and
> RelationB to be finished ...

Good point.  Because we are only doing one table at a time, they could
get in and do something, but they could also get part-way in and have
another table locked, and since we are only locking one at a time, it
seemed better to get it all done first.  Comments?

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