query-optimization

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MySQL query uses too much CPU

I use the following query to find users that I 开发者_如何学Cneed to send daily reminders based on their settings and timezone. It works but turned up that it uses about 50% CPU and its really heavy e[详细]

2023-04-09 09:47 分类：问答
Optimize this query with multiple joins

I have a query that keeps timing out in SQL Server. The biggest table in the query only has a few hundred rows. Basically I\'m trying to match up data in a bunch of tables with the novaPost field in t[详细]

2023-04-09 02:51 分类：问答
MySQL: Why does an Order By ID runs much slower than Order By other Columns?

I am using MySQL version 5.5.14 to run the following query, QUERY 1, from a table of 5 Million rows: SELECT P.ID, P.Type, P.Name, P.cty[详细]

2023-04-08 18:42 分类：问答
join versus explicit in condition

arethere some valid reasons, in a Oracle db, to preferring in a generic query, a filter condition expressed by a join table , instead ofa filter with anIN condition with a large number of elements (so[详细]

2023-04-08 16:17 分类：问答
MySQL - Views - Super slow query

This is a weird one. I am trying to use Views in MySQL (I\'m reasonably new to MySQL with more experience with Sybase and SQL Server). Any way this new project we are using MySQL as it seems to have g[详细]

2023-04-08 15:35 分类：问答
MySQL query optimisation - to alias or not?

Is there any major difference from an optimisation point of view between the following two alternatives? In the first option I alias the table, so the total_paid calculation is only run once. In the s[详细]

2023-04-07 22:17 分类：问答
How to get a optimized paginated list from a query that has a UNION ALL?

I have a query formed by an UNION ALL from two tables. The results have to be ordered and paginated (like the typical list of a web application).[详细]

2023-04-07 20:45 分类：问答
Help me optimize this query

I have this query for an application that I am designing. There is a table of references, an authors table and a reference_authors table. There is a sub query to return all authors for a g开发者_JS百科[详细]

2023-04-07 10:01 分类：问答
Identical query plan with radically different performance based on one improbable parameter?

I have an ad-hoc query that should be pretty zippy (I have a DBA background and I\'m pretty good at optimization) and in almost all cases it is. HOWEVER, when I supply a specific parameter to the quer[详细]

2023-04-06 20:43 分类：问答
How to optimize this sql delete statement

I have 3 tables, the first one, table1, has as primary key the id column, the second table (table2) has a column table1_id that refer as foreign key to the table1.id, the third table (table3) has, as[详细]

2023-04-06 13:58 分类：问答