Re: Merge Append Patch merged up to 85devel

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Gregory Stark <stark(at)mit(dot)edu>
Cc: Postgres <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Merge Append Patch merged up to 85devel
Date: 2009-07-05 21:34:49
Message-ID: 958765EE-149B-4589-9331-CEE0759639C6@gmail.com
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On Jul 5, 2009, at 10:02 AM, Gregory Stark <stark(at)mit(dot)edu> 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.

Can you provide some more details about the objective of this patch?
Or a link to previous discussion?

Thanks,

...Robert

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