Re: Connections hang indefinitely while taking a gin index's LWLock buffer_content lock

Hi!

> 10 дек. 2018 г., в 0:25, Alexander Korotkov <aekorotkov(at)gmail(dot)com> написал(а):
>>
>> There's a patch above in this thread 0001-Use-correct-locking-protocol-during-GIN-posting-tree.patch where I propose stamping every deleted page with GinPageSetDeleteXid(page, ReadNewTransactionId()); and avoid reusing the page before TransactionIdPrecedes(GinPageGetDeleteXid(page), RecentGlobalDataXmin).
>> Should we leave alone this bug for future fixes to keep current fix noninvasive?
>
> I think since is separate bug introduced in PostgreSQL 9.4, which
> should be backpatched with separate commit. Could you please extract
> patch dealing with GinPageSetDeleteXid() and GinPageGetDeleteXid().
> The rest of work made in your patch should be considered for master.

PFA this part. In thread about GiST vacuum Heikki was not very happy with reusing PageHeader->pd_prune_xid for this. But we somewhat concluded that this might be OK.
Anyway, there's whole page, we can store those bits anywhere.

> BTW, what do you think about locking order in ginRedoDeletePage()? Do
> you have any explanation of current behavior?
It seems to me that locking order must be left->deleted->parent.

Best regards, Andrey Borodin.