On 12 November 2012 14:51, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> The 9.0 code is broken, however. In
>> 9.0, when a child page is split, the parent and new children are kept
>> locked until the downlinks are inserted/updated. If a concurrent scan
>> comes along and sees that incomplete state, it will miss tuples on the
>> new right siblings. We rely on a rm_cleanup operation at the end of WAL
>> replay to fix that situation, if the downlink insertion record is not
>> there. I don't see any easy way to fix that, unfortunately. Perhaps we
>> could backpatch the 9.1 rewrite, now that it's gotten some real-world
>> testing, but it was a big change so I don't feel very comfortable doing
>> that.
>
> Me either. Given the lack of field complaints, I think we're better
> advised to just leave it unfixed in 9.0. It'd not be a step forward
> if we broke something trying to make this work.
Agreed. Most people running 9.0 with GIST indexes have already upgraded.
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