> On 9/4/2015 8:28 AM, Tatsuo Ishii wrote:
>>>
>>> Attached hack fixes the symptom but perhaps not the correct fix for this.
>>
>> Why can't we fix summarize_range() in brin.c:
>>
>> IndexBuildHeapRangeScan(heapRel, state->bs_irel, indexInfo, false, true,
>> heapBlk, state->bs_pagesPerRange,
>> brinbuildCallback, (void *) state);
>>
>> This currently thoughtlessly passes scannumblocks as
>> state->bs_pagesPerRange. Shouldn't we change this so that
>> (scanStartBlock + scanNumBlocks) does not exceed scan->rs_nblocks?
>>
>
> Ah, it did cross my mind to the fix it in brin.c but was not sure. I did
> it that way in the attached patch.
Amit,
I have looked into your patch and am a little bit worried because it
calls RelationGetNumberOfBlocks() which is an expensive function.
I think there are two ways to avoid it.
1) fall back to your former patch. However it may break existing behavior what you said. I think there's very little
chanceit actually happens because IndexBuildHeapRangeScan() is only used by brin (I confirmed this). But Alvaro said
somepatches may be it's customers. Robert, Amit, Can you please confirm this?
2) change the signature of IndexBuildHeapRangeScan() to be able to teach it to limit the target block number to not
exceedthe last page of the relation. Again this may break someone's patch and need confirmation.
What do you think?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
