enq: TM – contention – Oracle wait event

Oracle acquires a table lock on a child table if it’s performing modifications on the primary key column in the parent table that’s referenced by the foreign key of the child table. And these locks on the child table are full table locks (TM) i.e. these locks aren’t restricted to any row but to the…

Understanding TKProf output

In the previous post (Oracle TKProf Usage), we saw how to generate a SQL Trace and then how to format it using TKProf. In that post we create a trace for following SQL statement:- select * from all_objects; In this post we would interpret TKProf output of that SQL query. Following is the TKProf Output…

Oracle TKProf Usage

The TKProf facility accepts as input a SQL trace file and produces a formatted output file. TKPROF filename_source filename_output EXPLAIN=[username/password] SYS=[YES/No] TABLE=[tablename] filename_source: The trace file that needs to be formatted.filename_output: The output file where the formatted file will be written.EXPLAIN: This option causes TKProf to generate an execution plan for each SQL statement in…

How to enable 10046 Trace (SQL_TRACE) to troubleshoot performance issues

Event 10046 is used to gather extended SQL_TRACE information for Oracle sessions. This article describes how to enable event 10046 to get extended information to troubleshoot a performance issue. To gather 10046 trace at the session level: alter session set tracefile_identifier=’10046′; alter session set timed_statistics = true;alter session set statistics_level=all;alter session set max_dump_file_size = unlimited;alter…