From: | "Matt Magoffin" <postgresql(dot)org(at)msqr(dot)us> |
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To: | pgsql-jdbc(at)postgresql(dot)org |
Subject: | very large result sets and ResultSet.relative() to jump to a desired offset |
Date: | 2008-09-24 01:56:18 |
Message-ID: | 50687.192.168.1.106.1222221378.squirrel@msqr.us |
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Lists: | pgsql-jdbc |
When executing a large query, I am to understand that for server-side
cursors to be used (so to not run out of memory by loading the entire
result set into memory at once) I need to specify
ResultSet.TYPE_FORWARD_ONLY and then stmt.setFetchSize(x).
However, I'd like to be able to jump to the Xth result and display only Y
results, i.e. support pages of results and allow jumping to arbitrary
pages and thus arbitrary offsets in the result query. In code I used to do
set ResultSet.TYPE_SCROLL_INSENSITIVE, stmt.setFetchSize(Y), and then
rs.relative(X) where stmt is a Statement and rs is a ResultSet.
This causes the entire result set to get loaded into memory. To use a
FORWARD_ONLY result, I can't use ResultSet.relative() anymore. Is there
any alternative, other than perhaps calling ResultSet.next() X times
before returning the results? For very large results (millions of rows)
this seems like a slow solution, as I assume that all results will
actually get passed through JDBC just to jump to the desired row.
-- m@
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Next Message | Oliver Jowett | 2008-09-24 06:00:52 | Re: very large result sets and ResultSet.relative() to jump to a desired offset |
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