Re: Changeset Extraction v7.6.1 - Mailing list pgsql-hackers

From Robert Haas
Subject Re: Changeset Extraction v7.6.1
Date
Msg-id CA+TgmoZ_gUGkx92NbNs5ui5QzbWrfL=fsTv7uTb0D+5eweVdqQ@mail.gmail.com
Whole thread Raw
In response to Re: Changeset Extraction v7.6.1  (Andres Freund <andres@2ndquadrant.com>)
Responses Re: Changeset Extraction v7.6.1  (Andres Freund <andres@2ndquadrant.com>)
List pgsql-hackers
On Fri, Feb 21, 2014 at 8:27 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> On 2014-02-21 08:16:59 -0500, Robert Haas wrote:
>> On Fri, Feb 21, 2014 at 6:07 AM, Andres Freund <andres@2ndquadrant.com> wrote:
>> > I can sympathize with the "too much during init" argument, but I don't
>> > see how moving stuff to the first call would get rid of the problems. If
>> > we fail later it's going to be just as confusing.
>>
>> No, it isn't.  If you fail during init the use will expect the slot to
>> be gone.  That's the reason for all of this complexity.  If you fail
>> on first use, the user will expect the slot to still be there.
>
> The primary case for failing is a plugin that either doesn't exist or
> fails to initialize, or a user aborting the init. It seems odd that a
> created slot fails because of a bad plugin or needs to wait till it
> finds a suitable snapshot record. We could add an intermediary call like
> pg_startup_logical_slot() but that doesn't seem to have much going for
> it?

Well, we can surely detect a plugin that fails to initialize before
creating the slot on disk, right?

I'm not sure what "fails to initialize" entails.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company



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