Re: GIN improvements part 1: additional information

On Tue, Jan 21, 2014 at 4:28 PM, Alexander Korotkov <aekorotkov(at)gmail(dot)com>wrote:

> I noticed that the gin vacuum redo routine is dead code, except for the
>> data-leaf page handling, because we never remove entries or internal nodes
>> (page deletion is a separate wal record type). And the data-leaf case is
>> functionally equivalent to heap newpage records. I removed the dead code
>> and made it more clear that it resembles heap newpage.
>>
>> Attached is a yet another version, with more bugs fixed and more comments
>> added and updated. I would appreciate some heavy-testing of this patch now.
>> If you could re-run the tests you've been using, that could be great. I've
>> tested the WAL replay by replicating GIN operations over streaming
>> replication. That doesn't guarantee it's correct, but it's a good smoke
>> test.
>
>
> I tried my test-suite but it hangs on index scan with infinite loop. I
> re-tried it on my laptop with -O0. I found it to crash on update and vacuum
> in some random places like:
> Assert(GinPageIsData(page)); in xlogVacuumPage
> Assert(ndecoded == totalpacked); in ginCompressPostingList
> Trying to debug it.
>

Another question is about dataPlaceToPageLeaf:

while ((Pointer) seg < segend)
{
if (ginCompareItemPointers(&minNewItem, &seg->first) < 0)
break;

Shouldn't we adjust seg to previous segment? If minNewItem is less than
seg->first we should insert it to previous segment.

------
With best regards,
Alexander Korotkov.