Support SKIP LOCKED for SelectStatement

[Stumblinbear]

I'm working on implementing a job queue using Postgres, and I need to be able to add SKIP LOCKED to my select queries

[tyt2y3]

Is it an extension to #117 ?
But seriously, it seems to be difficult enough to done a queue right

[Stumblinbear]

Possibly. I'm unusure what the best route to implement it would be. With Postgres, all you need to do is add SKIP LOCKED onto a SELECT query, and it'll skip any row currently locked by a transaction. So all I have to do is: DELETE FROM "jobs" WHERE "jobs"."id" = (SELECT "id" FROM "jobs" WHERE "execute_at" < $1 ORDER BY "id" ASC FOR UPDATE SKIP LOCKED LIMIT 1) RETURNING "type_of", "data" inside of a transaction, do the work, then commit the transaction. Any other server looking for jobs will skip over any currently running jobs, and if the transaction fails or the client gets disconnected, the row gets unlocked. I'm currently using it without SKIP LOCKED (which means only one can only process one job at a time across servers, but its fine for now).

I'm currently using the transaction branch (even with the lifetime issue (which I haven't run into), it's working great).

Do let me know if this is more difficult than it seems on the surface to add support for!