Unnecessary BUFFER SORT Operations - Parallel Concatenation Transformation
When using Parallel Execution, depending on the plan shape and the operations used, Oracle sometimes needs to turn non-blocking operations into blocking operations, which means in this case that the...
View Article"SELECT * FROM TABLE" Runs Out Of TEMP Space
Now that I've shown in the previous post in general that sometimes Parallel Execution plans might end up with unnecessary BUFFER SORT operations, let's have a look what particular side effects are...
View ArticleVideo Tutorial: XPLAN_ASH Active Session History - Introduction
I finally got around preparing another part of the XPLAN_ASH video tutorial.This part is about the main funcationality of XPLAN_ASH: SQL statement execution analysis using Active Session History and...
View ArticleBig Nodes, Concurrent Parallel Execution And High System/Kernel Time
The following is probably only relevant for customers that run Oracle on big servers with lots of cores in single instance mode (this specific problem here doesn't reproduce in a RAC environment, see...
View ArticleIs SLOB AWR Generation Really, Really, Really Slow on Oracle Database...
If you are testing SLOB against 11.2.0.4 and find that the AWR report generation phase of runit.sh is taking an inordinate amount of time (e.g., more than 10 seconds) then please be aware that, in the...
View ArticleCombining Features - Wrong Results With Scalar Subquery Caching
Quite often you can get into trouble with Oracle when you start combining different features.In this case of one my clients it is the combination of user-defined PL/SQL functions that can raise...
View ArticleAdaptive Cursor Sharing Fail
Here is another example (besides the fact that Adaptive Cursor Sharing only gets evaluated during a PARSE call (still valid in 12c) and supports a maximum of 14 bind variables) I've recently come...
View ArticleOracle Database Physical I/O IOPS And Throughput Benchmark
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View ArticleNo Asynchronous I/O When Using Shared Server (Also Known As MTS)
I've recently had a case at a client where it was questioned why a particular application was seemingly not making full use of the available I/O capabilities - in comparison to other databases /...
View ArticleI/O Benchmark Minor Update
I've recently published a new version 1.03 of the I/O benchmark scripts on #333333;">my #336699;">github repository#333333;"> (ideally pick the #336699;">IO_BENCHMARK.ZIP containing all the...
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