Mysql select count optimization

相關問題 & 資訊整理

Mysql select count optimization

2010年12月17日 — 10 Answers · Add an auto increment field to the table. It looks you wouldn't delete from the table, so you can use simple math to find the record ...,2020年9月20日 — SELECT COUNT(*) FROM table WHERE active_calls = 1 ... As long as the first part is not used in the query, MySQL has no easy access to the ... ,2013年10月9日 — As of MySQL 5.1.6 you can use the Event Scheduler and insert the count to a stats ... EXPLAIN SELECT COUNT(id) FROM data USE INDEX (PRIMARY). ,2014年8月11日 — Create the table that holds the count number you are interested in. Every time you update / insert / delete the entity or area record - update ... ,A correlated subquery can be a fast method: SELECT es.id, es.title, (select count(*) from eb_evaluation_user_symptom eus where es.id ... ,2011年8月24日 — Here's an easy way to find the bottleneck: run the query piece by piece. Just do select count() from file_item and make sure that returns ... ,2011年7月13日 — If the source are known or you want to find the count for specific source, then you can try like this. select count(source= 'A' or NULL) as A, ... ,2013年2月25日 — SELECT COUNT(*) from table1 WHERE field1 IN ('val1','val2') OR field2 IN ('val3','val4'); · ALTER TABLE table1 ADD INDEX `field1_field2_idx` (` ... ,2016年2月29日 — SELECT COUNT(id) FROM thetable;. Being because the id column not null, indexed (actually it's the primary key), which means that it's not null ... ,1000 results — mysql> SELECT actor_id, COUNT(*) FROM sakila.film_actor GROUP BY actor_id;. This query returns only 200 rows, but it needs to read thousands of rows ...

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Mysql select count optimization 相關參考資料
optimize mysql count query - Stack Overflow

2010年12月17日 — 10 Answers · Add an auto increment field to the table. It looks you wouldn't delete from the table, so you can use simple math to find the record ...

https://stackoverflow.com

Improve InnoDB count(*) performance - Stack Overflow

2020年9月20日 — SELECT COUNT(*) FROM table WHERE active_calls = 1 ... As long as the first part is not used in the query, MySQL has no easy access to the ...

https://stackoverflow.com

How to optimize COUNT(*) performance on InnoDB by using ...

2013年10月9日 — As of MySQL 5.1.6 you can use the Event Scheduler and insert the count to a stats ... EXPLAIN SELECT COUNT(id) FROM data USE INDEX (PRIMARY).

https://stackoverflow.com

Mysql Count query optimization - Stack Overflow

2014年8月11日 — Create the table that holds the count number you are interested in. Every time you update / insert / delete the entity or area record - update ...

https://stackoverflow.com

How can I optimise COUNT with GROUPBY mysql query?

A correlated subquery can be a fast method: SELECT es.id, es.title, (select count(*) from eb_evaluation_user_symptom eus where es.id ...

https://stackoverflow.com

How to optimize a count SQL query on a big table - Stack ...

2011年8月24日 — Here's an easy way to find the bottleneck: run the query piece by piece. Just do select count() from file_item and make sure that returns ...

https://stackoverflow.com

MySQL: Optimizing COUNT(*) and GROUP BY - Stack Overflow

2011年7月13日 — If the source are known or you want to find the count for specific source, then you can try like this. select count(source= 'A' or NULL) as A, ...

https://stackoverflow.com

Optimize MySQL COUNT (*) query - Cloud Invent

2013年2月25日 — SELECT COUNT(*) from table1 WHERE field1 IN ('val1','val2') OR field2 IN ('val3','val4'); · ALTER TABLE table1 ADD INDEX `field1_field2_idx` (` ...

https://cloudinvent.com

MySQL COUNT(*) performance - DBA StackExchange

2016年2月29日 — SELECT COUNT(id) FROM thetable;. Being because the id column not null, indexed (actually it's the primary key), which means that it's not null ...

https://dba.stackexchange.com

Chapter 4. Query Performance Optimization - O'Reilly Media

1000 results — mysql> SELECT actor_id, COUNT(*) FROM sakila.film_actor GROUP BY actor_id;. This query returns only 200 rows, but it needs to read thousands of rows ...

https://www.oreilly.com