| From: | Oliver Jowett <oliver(at)opencloud(dot)com> |
|---|---|
| To: | Jack Orenstein <jao(at)geophile(dot)com> |
| Cc: | psql-jdbc(at)postgresql(dot)org |
| Subject: | Re: Queries with large ResultSets |
| Date: | 2004-05-20 04:55:14 |
| Message-ID: | 40AC3A32.40000@opencloud.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-jdbc |
Jack Orenstein wrote:
> If I'm reading the source code correctly, the PostgreSQL 7.3.4 JDBC
> driver creates a ResultSet by evaluating the entire query, and putting
> all the rows into a Vector. ResultSet.next() iterates over the
> Vector. Is that in fact what is happening?
That's probably true for the 7.3.4 driver, which is quite old now.
The latest 7.4 drivers (which will work against a 7.3 server) will use a
cursor to fetch the resultset incrementally when:
- the statement fetchsize is non-zero; and
- autocommit is off (and
- the statement is TYPE_FORWARD_ONLY; and
- the query is a single SELECT
There's also been a patch posted recently (check the archives) that
allows use of cursors with scrollable resultsets.
-O
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