With default sampling level of 2 (from 10g onwards) , dynamic sampling is performed only for the objects for which statistics do not exist. If…
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Category: performance
What is SQL PROFILE in oracle?
You might have heard of SQL profile and SQL baselines in performance tuning chapters. Lets today go through details about sql profile. What is SQL…
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Partition Pruning and NLS Settings
NLS (National Language Support) parameters are very useful for multilingual applications in an Oracle database. But it is important to understand their impact on query…
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How to Lock, Unlock, Transfer Statistics in oracle
Locking Stats To prevent statistics being overwritten, you can lock the stats at schema, table or partition level. EXEC DBMS_STATS.lock_schema_stats(‘SCOTT’); EXEC DBMS_STATS.lock_table_stats(‘SCOTT’, ‘EMP’); EXEC DBMS_STATS.lock_partition_stats(‘SCOTT’,…
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Understanding IOPS vs. throughput
Input/output operations per second (IOPS) and data throughput are two popular performance characteristics of any storage system. In the early days of computer technology, when…
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