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nenadnoveljic.com | ||
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jonathanlewis.wordpress.com
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| | | | | In response to a recent lamentation from Richard Foote about the degree of ignorance regarding the clustering_factor of indexes I commented on the similar degree of ignorance regarding the syntax of a specific hint, namely use_nl(a b), pointing out that this does not mean "do a nested loop from a to b". My comment was... | |
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blog.sqlora.com
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| | | | | Learn how implicit RAW-to-VARCHAR2 conversions in Oracle break histograms, hurt optimizer estimates, and how to fix them safely. | |
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blog.tanelpoder.com
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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. | |
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nenadnoveljic.com
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| | | Oracle's heuristics previously avoided considering fixed tables for Join Predicate Pushdown (JPPD) transformation, leading to suboptimal plans. Enforcing predicate pushing into the view with the PUSH_PRED hint was a workaround. Oracle addressed this in the 21c release, evaluating fixed tables for JPPD. | ||
