I've added this to the July commitfest.
Gregory Stark wrote:
> Here's a copy of the merge-append patch that I sent months ago merged up to
> head. I haven't really added any additional functionality since then.
>
> Heikki suggested I separate the Append and MergeAppend nodes into two executor
> nodes. I had that half done in my tree but looking it over it leads to a lot
> of duplicated code and a strange effect that there's on Path node but two
> Executor nodes which seems strange. I'm not sure which way to go here but at
> least for now I'm leaving it this way since it's less code to write. If we
> want it the other way to commit then I'll do it.
>
> The other pending question is the same I had back when I originally submitted
> it. I don't really understand what's going on with eclasses and what
> invariants we're aiming to maintain with them. I don't see a problem tossing
> all the child relation attributes into the same eclass even though they're not
> strictly speaking "equivalent". No join above the append path is going to see
> the child attributes anyways. But that might be shortsighted as I'm not really
> sure what the consequences are and what other uses we have envisioned for
> eclasses in the future.
>
>
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-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com