Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Patch applied. Thanks.
> * block is not currently in memory.
> */
> bufHdr = BufferAlloc(reln, blockNum, &found);
> + /* we are guaranted that nobody else has touched this
> will-be-new block */
> + Assert(!(found && isExtend));
> if (found)
> BufferHitCount++;
> }
This patch is utterly wrong. Please revert it.
The case it is Asserting can't happen is explained in the comment a
couple dozen lines further down:
* try to extend a relation
* read smgrnblocks to find the current relation length
* allocate an empty buffer for the N+1'st page of the rel
* call smgrextend
* smgrextend fails for some reason (eg, no space left on disk)
* buffer remains present, but is not BM_VALID
* awhile later, try to extend relation again
* read smgrnblocks to find the current relation length
* allocate a buffer for the N+1'st page of the rel
This is entirely likely to find the same non-BM_VALID buffer that was
assigned in the first iteration.
regards, tom lane
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