Symptom
After upgrading from ASE 12.5 to ASE 15.0 and later releases, correlated subquery could show performance degradation due to order in which subqueries are evaluated in ASE 15.0 & later.
- A query could show more logical I/Os
- Different optimization goals viz., oltp, mix, dss, all show same problem
- The reorg (for defragmentation) improves matters but does not appear to solve the problem
- Using compatibility mode resolves this problem
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Environment
- SAP Adaptive Server Enterprise (ASE) 15.7
- SAP Adaptive Server Enterprise (ASE) 16.0
- Sybase Adaptive Server Enterprise (ASE) 15.0
- Sybase Adaptive Server Enterprise (ASE) 15.5
Product
SAP Adaptive Server Enterprise 15.7 ; SAP Adaptive Server Enterprise 16.0 ; Sybase Adaptive Server Enterprise 15.0 ; Sybase Adaptive Server Enterprise 15.5
Keywords
SAP ASE 15 performance, coorelated subquery, high logical I/O, subquery, slow , KBA , optimizer , BC-SYB-ASE , Sybase ASE Database Platform (non Business Suite) , Bug Filed
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