Re: Issue with logical replication: MyPgXact->xmin already is valid

On 06/10/17 12:16, Konstantin Knizhnik wrote:
> When creating logical replication slots we quite often get the following
> error:
>
> ERROR:  cannot build an initial slot snapshot when MyPgXact->xmin
> already is valid
>
> which cause restart of WAL sender.
> The comment to this line doesn't clarify much:
>
>     /* so we don't overwrite the existing value */
>     if (TransactionIdIsValid(MyPgXact->xmin))
>         elog(ERROR, "cannot build an initial slot snapshot when
> MyPgXact->xmin already is valid");
>>
> I wonder if it is normal situation or something goes wrong?
>

Hi,

no it's not normal situation, it seems you are doing something that
assigns xid before you run the CREATE_REPLICATION_SLOT command on that
connection.

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Petr Jelinek http://www.2ndQuadrant.com/
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