>From IBM doc: ============= Operator name: GENROW Represents: A built-in function that generates a table of rows, using no input from tables, indexes, or operators.
GENROW may be used by the optimizer to generate rows of data (for example, for an INSERT statement or for some IN-lists that are transformed into joins). To view the estimated statistics for the tables generated by the GENROW function, double-click on its node. Abhijit -----Original Message----- From: Reys, Ellen [mailto:[EMAIL PROTECTED] Sent: Monday, September 08, 2003 7:18 PM To: '[EMAIL PROTECTED]'; [EMAIL PROTECTED] Subject: RE: [DB2EUG] SYSIBM.GENROW showing up in explains? I have seen GENROW many times in the Optimized SQL statement in the exfmt output. In my case, this was related to the eliminating unqualified branches in the UNION ALL VIEW when joined to a table. In that case, the unqualified branch is transformed to a nested loop join (NLJOIN) with the outer input (left hand side) is a GENROW and the inner input (right hand side) is the table name (if doing table scan) or one of the index of that table (if doing index scan) of the unqualified branch. The way the plan works is it starts to evaluate the predicate in the GENROW, which is in the form of: (query predicate) AND (view definition predicate) For example, month_id = 72001 AND month_id in (102000,112000,122000) In this case, the predicate will return false and the GENROW will produce no row. The NLJOIN will not access its inner input, which is the access to the table (or index). Sorry, if I cannot explain properly. Ellen Klebaner-Reys Data Management Services Inovant - a Visa Solutions Company [EMAIL PROTECTED]/650-432-1746 m/s: 3125-1D -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Monday, September 08, 2003 2:35 PM To: [EMAIL PROTECTED] Subject: [DB2EUG] SYSIBM.GENROW showing up in explains? Somehow SYSIBM.GENROW keeps popping up in explain diagrams. Can't find this object however. Does anyone know what's the purpose of this one? Thanks, Tim - ::: When replying to the list, please use 'Reply-All' and make sure ::: a copy goes to the list ([EMAIL PROTECTED]). *** To unsubscribe, send 'unsubscribe' to [EMAIL PROTECTED] *** For more information, check http://www.db2eug.uni.cc - ::: When replying to the list, please use 'Reply-All' and make sure ::: a copy goes to the list ([EMAIL PROTECTED]). *** To unsubscribe, send 'unsubscribe' to [EMAIL PROTECTED] *** For more information, check http://www.db2eug.uni.cc - ::: When replying to the list, please use 'Reply-All' and make sure ::: a copy goes to the list ([EMAIL PROTECTED]). *** To unsubscribe, send 'unsubscribe' to [EMAIL PROTECTED] *** For more information, check http://www.db2eug.uni.cc
