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Queries with the following attributes continue to run with the Classic Query Engine:
- Non-Read (INSERT with subselect can use SQE) - LIKE predicates - UNIONS - View or Logical File references - Subquery - Derived Tables & Common Table expressions - LOB columns - NLSS/CCSID translation between columns - DB2 Multisystem - Non-SQL queries (QQQQry API, Query/400, OPNQRYF) - Queries with the STAR_JOIN QAQQINI attribute But there is a newer presentation that has more on what is allowed - http://www-03.ibm.com/servers/eserver/iseries/db2/pdf/sqeoverview_v5r3.pdfThis is worth keeping up on, I think, and it is a good reason to stay current on the DB group PTF.
Vern At 11:36 AM 12/21/2005, you wrote:
Douglas, Embedded SQL is one of those beasts that wears many faces.... You have certain performance issues if you're dealing with dynamic (or Extended Dynamic) SQL that you won't have for static SQL. Using static SQL with parameter markers or host variables for selection criteria would usually perform better than a dynamic (prepared) statement, because the SQL templates can be retained in the "package" for the next run. There's also a new consideration, in that Query/400, QMQRY, OPNQRYF, and so forth can only use what's known as CQE (Classic Query Engine), where embedded SQL may be allowed to used the new SQE (SQL Query Engine) which contains all the new optimized code that the iSeries has inherited from other DB2 platforms. SQL performance is still a bit like alchemy... It's more an art than a science, but mastery of the techniques can pay off handsomely. Eric DeLong Sally Beauty Company MIS-Project Manager (BSG) 940-297-2863 or ext. 1863 -----Original Message----- From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of Douglas W. Palme Sent: Wednesday, December 21, 2005 11:05 AM To: Mid Range List Subject: embedded SQL versus Query Are there any performance issues to consider when looking at embedded SQL versus Query400? It seems that Query400 might actually run faster, but I can definitely see the advantages of creating an SQL statement on the fly per se. Thoughts, comments? Tell me I'm nuts....ok skip the last one, that's a given. If you bought it, it was hauled by a truck - somewhere, sometime. -- This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/midrange-l or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/midrange-l. -- This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe, unsubscribe, or change list options, visit: http://lists.midrange.com/mailman/listinfo/midrange-l or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take a moment to review the archives at http://archive.midrange.com/midrange-l.
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