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 jonathanlewis.wordpress.com
dbms_xplan | Oracle Scratchpad
| | rwijk.blogspot.com
About Oracle: dbms_xplan.display_cursor
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| | tanelpoder.com
Alter session force parallel query doesn't really force anything | Tanel Poder Blog
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| | Jonathan Lewis has already written about this behavior from the angle of PARALLEL hints. I'm writing a similar article just because the word FORCE in the ALTER SESSION FORCE PARALLEL QUERY syntax. Force should mean that some behavior would always happen (when possible), right? Let's test: SQL> CREATE TABLE t AS SELECT * FROM dba_objects; Table created. SQL> CREATE INDEX i ON t(owner); Index created. SQL> @gts t Gather Table Statistics for table t... PL/SQL procedure successfully completed. Now let's "force" the parallel query in my session, run the query and check the execution plan: - Linux, Oracle, SQL performance tuning and troubleshooting training & writing.
| | kerryosborne.oracle-guy.com
Kerry Osborne's Oracle Blog » Blog Archive » GATHER_PLAN_STATISTICS
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| | dincosman.com
Direct Path Read Decision in Oracle: Beyond the Optimizer - Osman's DBlog
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| The performance issue with an SQL query was resolved by using the /*+ PARALLEL(2) */ hint, reducing execution time from 180-200 seconds to milliseconds. The decision to perform a direct read from disk to memory instead of reading blocks from disk was made by the database engine and is controlled by the hidden "_serial_direct_read" parameter....