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richardfoote.wordpress.com | ||
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jonathanlewis.wordpress.com
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| | | | | I'm encroaching on Richard Foote's territory here - with plans to write a few details about some of the implementation details of Oracle's B-tree indexes. My strategy, though, is to entertain by asking a few questions that might prompt a little speculation before giving some answers. So ... After running validate index against a particular... | |
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jonathanlewis.wordpress.com
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| | | | | I've discussed the capabilities of the dbms_xplan package in a couple of posts already; and shown how useful it can be in two examples: understanding a problem with filter subquery selectivity and understanding why some Cartesian merge joins were appearing unexpectedly. Let me make a crucial point about execution plans (again): if you have a... | |
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jonathanlewis.wordpress.com
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| | | | | 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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iusoltsev.wordpress.com
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| | | ??????? ?????? ?? ??????? ??????????? 465 ??????! SELECT A.ID, A.LOGIN, A.NAME, A.LASTNAME, A.EMAIL FROM ACCOUNT A WHERE (A.LOGIN LIKE '%%') AND (A.NAME LIKE '%????????%' OR A.LASTNAME LIKE '%????????%') AND A.COMPANY_ID = 1 ORDER BY A.LOGIN ??? ???????, ????????? ???? ?? ??????? A.COMPANY_ID = 1 ???????? ??????? ???????????????? SQL> SELECT 'ALL' as "Condition", count(*) FROM ACCOUNT... | ||
