Re: logtape.c stats don't account for unused "prefetched" block numbers - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: logtape.c stats don't account for unused "prefetched" block numbers
Date
Msg-id ace3c065e689ba4c7279126963ad50ea69d2a507.camel@j-davis.com
Whole thread Raw
In response to Re: logtape.c stats don't account for unused "prefetched" block numbers  (Peter Geoghegan <pg@bowt.ie>)
Responses Re: logtape.c stats don't account for unused "prefetched" block numbers  (Peter Geoghegan <pg@bowt.ie>)
List pgsql-hackers
On Mon, 2020-09-14 at 19:29 -0700, Peter Geoghegan wrote:
> Let's assume that we'll teach LogicalTapeSetBlocks() to use
> nBlocksWritten in place of nBlocksAllocated in all cases, as now
> seems
> likely. Rather than asserting "nBlocksWritten == nBlocksAllocated"
> inside LogicalTapeSetBlocks() (as I suggested earlier at one point),
> we could instead teach LogicalTapeSetBlocks() to iterate through each
> tape from the tapeset and make sure each tape has no writes buffered
> (so everything must be flushed). We could add a loop that would only
> be used on assert-enabled builds.

Sounds reasonable.

> You suggested this yourself, Jeff (my suggestion about the assertion
> is just an expansion on your suggestion from earlier). This all seems
> like a good idea to me. Can you write a patch that adjusts
> LogicalTapeSetBlocks() along these lines? Hopefully the assertion
> loop
> thing won't reveal some other problem with this plan.

Sure. Will backporting either patch into REL_13_STABLE now interfere
with RC1 release in any way?

Regards,
    Jeff Davis





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