[Catalyst] Session duplicate key constraints on concurrent requests

[Tobias Kremer]

Hi Janne,

I appreciate your taking the time to look into this. Unfortunately your patches are for the Store::DBI backend, whereas I'm using Store::DBIC (DBIx::Class). The INSERT IGNORE solution is probably exactly what this case needs, but as you said, it's MySQL-specific and thus not suitable for the masses.

I suppose to really solve this for most databases, we'd first need a portable way to check if a database error is a duplicate key constraint error. This should probably be abstracted away in DBIx::Class.

Here's hoping that somebody comes up with a simpler solution ... My only alternative right now would be switching to a Memcached session backend.

--Toby



On 07.10.2011, at 21:25, Janne Snabb wrote:

> On Fri, 7 Oct 2011, Janne Snabb wrote:
> 
>> Something like this perhaps? Untested code.
> 
> Sorry about flooding. This is another much simpler solution but works
> only on MySQL. I think there is no standard SQL syntax to accomplish
> the same without extra DB fields.
> 
> --
> Janne Snabb / EPIPE Communications
> snabb at epipe.com - http://epipe.com/
> 
> 
> diff -U5 -r Catalyst-Plugin-Session-Store-DBI-0.16/lib/Catalyst/Plugin/Session/Store/DBI.pm Catalyst-Plugin-Session-Store-DBI-0.16+otherpatch/lib/Catalyst/Plugin/Session/Store/DBI.pm
> --- Catalyst-Plugin-Session-Store-DBI-0.16/lib/Catalyst/Plugin/Session/Store/DBI.pm	2010-03-24 04:47:13.000000000 +0700
> +++ Catalyst-Plugin-Session-Store-DBI-0.16+otherpatch/lib/Catalyst/Plugin/Session/Store/DBI.pm	2011-10-08 02:21:12.227212244 +0700
> @@ -156,11 +156,11 @@
>         check_existing          =>
>             "SELECT 1 FROM $table WHERE $id_field = ?",
>         update_session          =>
>             "UPDATE $table SET $data_field = ?, $expires_field = ? WHERE $id_field = ?",
>         insert_session          =>
> -            "INSERT INTO $table ($data_field, $expires_field, $id_field) VALUES (?, ?, ?)",
> +            "INSERT IGNORE INTO $table ($data_field, $expires_field, $id_field) VALUES (?, ?, ?)",
>         update_expires          =>
>             "UPDATE $table SET $expires_field = ? WHERE $id_field = ?",
>         delete_session          =>
>             "DELETE FROM $table WHERE $id_field = ?",
>         delete_expired_sessions =>
> 
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