Large queries; fetchsize, cursors and limit/offset
От | David Wall |
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Тема | Large queries; fetchsize, cursors and limit/offset |
Дата | |
Msg-id | 06b801c3a248$8b93f360$3201a8c0@rasta обсуждение исходный текст |
Ответ на | JDBC 2.0 Compatibility? ("Renaud Waldura" <renaud+pgsql@waldura.com>) |
Ответы |
Re: Large queries; fetchsize, cursors and limit/offset
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Список | pgsql-jdbc |
What are most people doing to handle queries with large result sets. By large, I mean results that have perhaps 200 or more rows and in which having the full resultset would likely be a performance and memory issue. Often, we have queries that could return thousands of rows, especially those performed by batch processing programs/threads. It seems that the setFetchSize() is not well implemented across JDBC platforms, and that the LIMIT/OFFSET combo, while workable despite the potential for overhead on the database (since it returns only a subset, yet the entire query must be evaluated) is not implemented everywhere, including Oracle 8i if I'm not mistaken. The other option appears to be to use cursors, though I'm not sure how well that's supported across JDBC drivers either. For sure, the syntax for declaring and using a cursor vary among different database, though I can work around that pretty easily. What are most people doing these days for handling large queries, especially those that have to support not only PostgreSQL, but also Oracle, DB2/UDB and/or MSFT SQLServer? Thanks, David
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