Re: [BUGS] Breakage with VACUUM ANALYSE + partitions

Hello Andres,

> I can think of a number of relatively easy ways to address this:
> 1) Just zap (or issue?) all pending flush requests when getting an
>   smgrinval/smgrclosenode
> 2) Do 1), but filter for the closed relnode
> 3) Actually handle the case of the last open segment not being
>   RELSEG_SIZE properly in _mdfd_getseg() - mdnblocks() does so.
>
> I'm kind of inclined to do both 3) and 1).

Alas I'm a little bit outside my area of expertise. Just for suggestion 
purpose, possibly totally wrong (please accept my apology if this is the 
case), the ideas I had while thinking about these issues, some may be 
quite close to your suggestions above:
 - keep track of file/segment closing/reopenings (say with a counter), so   that if a flush is about a file/segment
whichhas been closed or   reopened, it is just skipped. I'm not sure this is enough, because one   process may do the
filecleaning and another may want to flush, although   I guess there is some kind of locking/shared data structures to
manage  such interactions between pg processes.
 
 - because of "empty the bucket when filled behavior" of the current   implementation, a buffer to be flused may be
keptfor a very   long time in the bucket. I think that flushing advices become stale   after a while so should not be
issued(the buffer may have been   written again, ...), or the bucket should be flushed after a while   even of not
full.

Also, a detail in "pg_flush_data", there are a serie of three if/endif, 
but it is not obvious to me whether they are mutually exclusive while 
looking at the source, so I was wondering whether the code could try 
several flushings approaches one after the other... This is probably not 
the case, but I would be more at ease with a if/elif/elif/endif structure 
there so that is clearer.

-- 
Fabien.