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dioncho.wordpress.com
One of my colleagues sent following test case, of which he couldn't control the join order with hints. 1. Create objects - table t1, t2 and t3 2. Now Let's set the join order as T1->T2->T3, using global hints convention. But it seems that Oracle does not work as expected. It really seems that the... |
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jonathanlewis.wordpress.com
Jump to summary. A new optimizer feature that appears in 23c (probably not 21c) was the ability to push group by clauses into union all set operations. This will happen unhinted, but can be hinted with the highly memorable [no_]push_gby_into_union_all() hint that appeared in 23.1.0.0 according to v$sql_hint. and the feature can be disabled by... |
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leonotes.wordpress.com
transitive closure?Wiki?Oracle?... |
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dincosman.com
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.... |
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