From: | Rick Delaney <rick(at)consumercontact(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Jan Wieck <wieck(at)debis(dot)com>, pgsql-sql(at)postgreSQL(dot)org |
Subject: | Re: [SQL] Calculation dependencies in views |
Date: | 2000-01-06 19:42:05 |
Message-ID: | 3874F00D.F6A504B9@consumercontact.com |
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Thread: | |
Lists: | pgsql-sql |
Tom Lane wrote:
>
> Jan Wieck <wieck(at)debis(dot)com> writes:
>
> > These two examples will result in exactly the same querytree after
> > rewriting, if you SELECT from v1. The second needs two passes in the
> > rewriter, but that's the only difference.
>
> Actually, there's another big difference: the stored rule plan string
> for v1 in the second case is shorter than it is in the first case,
> because the a+b additions don't show up as operator nodes in v1's
> definition in the second case. (If the references to v1_sub were
> flattened out before the rule were stored, it wouldn't take two passes
> of rewriting to expand the rule. But they aren't, and it does ;-).)
Interesting. Anyway, I grok it now. Thank you both for all your help.
Cheers,
--Rick
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