Re: [HACKERS] Issue with logical replication: MyPgXact->xmin alreadyis valid

On 10/07/2017 04:26 PM, Petr Jelinek wrote:
>
> Hmm so you start transaction (you have to when running
> CREATE_REPLICATION_SLOT with USE_SNAPSHOT parameter). And while the slot
> is being created the config is reloaded. And since now you are in
> transaction the tsearch hook for GUC processing tries to access catalogs
> which sets the xmin for the transaction.

Actually this slot is implicitly created by LogicalRepSyncTableStart to perform initial data sync.

>
> That's not good, but I can't really say I have idea about what to do
> with it other than to set some kind of flag saying that logical decoding
> snapshot is being built and using that to skip catalog access which does
> not seem very pretty.
>
It is not quite clear from the comment why it is not possible to overwrite MyPgXact->xmin or just use existed value.

-- 
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company



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