| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Dmitri Bichko" <dbichko(at)aveopharma(dot)com> |
| Cc: | pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: UNION index use help |
| Date: | 2005-10-06 16:32:17 |
| Message-ID: | 20942.1128616337@sss.pgh.pa.us |
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| Lists: | pgsql-sql |
"Dmitri Bichko" <dbichko(at)aveopharma(dot)com> writes:
> Ok, I'm thoroughly confused.
You didn't say which PG version you are using, but if it's something
reasonably recent then it should be able to push upper qual conditions
down into a UNION. I think you are getting bit by this restriction:
* 3. For subqueries using UNION/UNION ALL/INTERSECT/INTERSECT ALL, we can
* push quals into each component query, but the quals can only reference
* subquery columns that suffer no type coercions in the set operation.
* Otherwise there are possible semantic gotchas.
You're getting burnt because you're unioning a text with a varchar.
Make the column types the same and it'll work better.
regards, tom lane
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