SQL Server: if possible, use OFFSET and FETCH instead of JDBC methods #300
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Signed-off-by: Richard DiCroce <Rich.DiCroce@scientificgames.com>
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create a PR for master, please. Thanks! |
This was referenced Nov 15, 2020
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Currently, EclipseLink uses Statement#setMaxRows() to apply a result limit when the target database is MS SQL Server. This is dangerous because mssql-jdbc implements setMaxRows() by executing SET ROWCOUNT, which applies to all queries made on the connection until SET ROWCOUNT is executed again.
Normally, that is not an issue, but it can become a problem if, for example, your query includes a call to a user-defined function that executes another query. When that happens, it creates truly baffling bugs that are very difficult to track down. mssql-jdbc acknowledges that SET ROWCOUNT is not an appropriate way to implement setMaxRows() but currently has no ability to replace it with something better; see microsoft/mssql-jdbc#176.
This PR alters SQLServerPlatform to add the OFFSET and FETCH NEXT clauses to the query, if the version of SQL Server in use supports them. This avoids EclipseLink calling setMaxRows(), and may improve query performance.
This PR is for 2.7. If it looks okay to whoever reviews it, I will open another PR for master.