From ssinger at ca.afilias.info  Sun Jul  6 12:05:43 2014
From: ssinger at ca.afilias.info (Steve Singer)
Date: Sun, 06 Jul 2014 15:05:43 -0400
Subject: [Slony1-hackers] initial setsync value
Message-ID: <53B99E07.2000807@ca.afilias.info>

In the copy_set function in the slon remote_worker when we copy the set 
from the origin we construct values for the initial snapshot (for 
sl_setsync) by the following method

* Get the max SYNC event on the origin and snapshot information for that 
sync
* Query all sl_log_1 and sl_log_2 entires that came in after that sync. 
This information populates the action list.

Why don't we just get the snapshot visibility information of what is and 
isn't visible to the copy_set transaction directly with 
txid_current_snapshot() ?

It seems simpler?   (I would guess that this is a left-over from the 
pre-8.3 days when txid_current_snapshot wasn't available?)

I ask because the current method work with logical replication because 
sl_log will be empty (but we still need the snapshot of the copy_set to 
filter stuff out later).   I'd like to modify copy_set to just use 
txid_current_snapshot for both logical and trigger based cases.

If there some reason why this won't work then please let me know.

Thanks


From jan at wi3ck.info  Sun Jul  6 12:48:59 2014
From: jan at wi3ck.info (Jan Wieck)
Date: Sun, 6 Jul 2014 15:48:59 -0400
Subject: [Slony1-hackers] initial setsync value
In-Reply-To: <53B99E07.2000807@ca.afilias.info>
References: <53B99E07.2000807@ca.afilias.info>
Message-ID: <CAGBW59foTzaHqbOgj3+_Babid2AiQrLTaT=6K0aUuPqUFWiSLQ@mail.gmail.com>

Wasn't that precisely one of our TODO items? I actually thought we did this
for 2.2 already, but the code shows otherwise.

Jan

--
Jan Wieck
Senior Software Engineer
http://slony.info
On Jul 6, 2014 3:05 PM, "Steve Singer" <ssinger at ca.afilias.info> wrote:

> In the copy_set function in the slon remote_worker when we copy the set
> from the origin we construct values for the initial snapshot (for
> sl_setsync) by the following method
>
> * Get the max SYNC event on the origin and snapshot information for that
> sync
> * Query all sl_log_1 and sl_log_2 entires that came in after that sync.
> This information populates the action list.
>
> Why don't we just get the snapshot visibility information of what is and
> isn't visible to the copy_set transaction directly with
> txid_current_snapshot() ?
>
> It seems simpler?   (I would guess that this is a left-over from the
> pre-8.3 days when txid_current_snapshot wasn't available?)
>
> I ask because the current method work with logical replication because
> sl_log will be empty (but we still need the snapshot of the copy_set to
> filter stuff out later).   I'd like to modify copy_set to just use
> txid_current_snapshot for both logical and trigger based cases.
>
> If there some reason why this won't work then please let me know.
>
> Thanks
>
>
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