sql-tuning

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SELECT clause using IN ... very slow?

Could you guys please review the following query to an Oracle DB and point out what\'s wrong: SELECT t1.name FROM t1, t2 WHERE t1.id = t2.id AND t2.empno IN (1, 2, 3, …, 200)[详细]

2023-03-27 16:34 分类：问答
Why the count(*) in a sql prepare statement type is really small?

I found the \"count() over()\" will be much faster compare to the \"select count() from table\". e.g use count(*) over[详细]

2023-03-10 23:54 分类：问答
Oracle SQL tuning based on hints- any good on recent versions?

I read that oracle\'s CBO(on recent versions) is so good that even if wors开发者_JS百科t possible join order is given, CBO automagically takes the best join order. So will hints like ORDERED do any go[详细]

2023-03-05 21:37 分类：问答
Special case of Equi Join

I came across this particular script which uses a special form of equi join. SELECT * FROM per_assignments a, per_assigment_types b[详细]

2023-03-04 03:41 分类：问答
Function-Based Index on numeric Column

I have a table containing some numeric columns, and i have to keep them numeric because most of the time i will benefit from that. But i need also to make a generic search on those columns using parti[详细]

2023-02-20 06:58 分类：问答
Sql tuning advisor(accepting profile)

I have created sql tuning task for some query and executed it.After generating report,It recommends me to run the following command:开发者_开发技巧[详细]

2023-01-27 22:25 分类：问答
MySQL last_query_cost for complex queries

when try开发者_运维百科ing to find the cost of a complex query (one with a sub-query in it) i get a value of 0.[详细]

2023-01-25 09:21 分类：问答
How do I tune a query

I have a query that is running slowly.I know gen开发者_运维知识库erally to make performance faster, limit joins, and try to use procs instead of straight queries.Due to business rules, I cannot use pr[详细]

2023-01-13 09:34 分类：问答
comparing a column with itself in WHERE clause of oracle SELECT

I ha开发者_开发知识库ve a multi-table SELECT query which compares column values with itself like below:[详细]

2023-01-04 21:37 分类：问答
Why is Oracle using a skip scan for this query?

Here\'s the tkprof output for a query that\'s running extremely slowly (WARNING: it\'s long :-) ): SELECT mbr_comment_idn, mbr_crt_dt, mbr_data_source, mbr_dol_bl_rmo_ind, mbr_dxcg_ctl_member, mbr_em[详细]

2022-12-29 21:09 分类：问答