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 tanelpoder.com
Alter session force parallel query doesn't really force anything | Tanel Poder Blog
| | blog.tanelpoder.com
Optimizer statistics-driven direct path read decision for full table scans (_direct_read_decision_statistics_driven) | Tanel Poder Blog
1.7 parsecs away

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| | Hello all fellow Oracle geeks and technology enthusiasts! Long time no see ;-) In the hacking session about Oracle full table scans and direct path reads I explained how the direct path read decision is not done by the optimizer, but instead during every execution, separately for every single segment (partition) scanned in the query. I also explained how the _small_table_thresholdparameter and theX$KCBOQH.NUM_BUF(which keeps track of how many buffers of any segment are currently cached) are used for determining whether to scan using direct path reads or not. - Linux, Oracle, SQL performance tuning and troubleshooting training & writing.
| | www.dbaglobe.com
Donghua's Blog - DBAGlobe: Subquery Performance Tuning (Part 1, IN, EXISTS and COUNT >0)
1.5 parsecs away

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| | A blog about on new technologie. Hands-on note about Hadoop, Cloudera, Hortonworks, NoSQL, Cassandra, Neo4j, MongoDB, Oracle, SQL Server, Linux, etc.
| | dincosman.com
Direct Path Read Decision in Oracle: Beyond the Optimizer - Osman's DBlog
1.9 parsecs away

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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....
| | jonathanlewis.wordpress.com
Bind Peeking | Oracle Scratchpad
12.2 parsecs away

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| Here's a simple detail about bind peeking (during optimisation) that makes a big difference to "fetch first/next" queries. The optimizer knows about your bind types, and can peek at the bind values - but that doesn't mean it will do something sensible with them. Here's a little model to demonstrate the problem - starting with...