Tagged Questions
1
vote
2answers
44 views
Prune unused joins
I have expected that selecting from a view would not join the tables from which I don't query any values, but it doesn't seem to be the case.
I have a bunch of tables with the following structure:
...
0
votes
1answer
66 views
Speed efficient query for membership first joined, latest category from membership table (min, max)
I have the following table representing membership information:
CREATE TABLE IF NOT EXISTS `membership` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`organisation_id` int(11) NOT NULL,
...
3
votes
3answers
237 views
Is it better to seperate a big query into multiple smaller queries?
There are situations which require to have really big query joining several tables together with sub select statements in them to produce the desired results.
My question is, should we consider using ...
0
votes
2answers
216 views
Slow query with straight_join for small result
I have a performance-problem with a query in my application and I don’t understand the behavior of mysql.
The query consists of different joins, especially the join to the mentioncache-table. If the ...
2
votes
1answer
253 views
inner join on PK with extra criteria slow despite indices?
Given the two tables below I am struggling to understand:
why is the third query slow even though first two queries are fast
what exactly is EXPLAIN saying
can I do anything to significantly speed ...
2
votes
1answer
307 views
Should I use left join to do my job in this scenario?
What I want to do is to find out the items which appeared more than once in this table:
mysql> desc tables;
+-----------------+---------------------+------+-----+---------+-------+
| Field ...
0
votes
1answer
257 views
Slow performance of MySQL Join Query
I have inherited a site (running Coldfusion8 and MySQL 5.0.88) with a product search using multiple criteria. I'm struggling with optimizing the search, especially a pricelist check, which makes the ...
2
votes
1answer
379 views
MySQL 5.5.8 InnoDB Foreign Key, JOIN performance
We are using aws/rds, MySQL 5.5.8. all InnoDB.
For performance purposes, we have merged some data-elements into varchar fields; mini-sized int and date type fields; added covering indexes; ...
3
votes
1answer
2k views
mySQL query optimisation — multiple joins or select … where not in (select distinct…)?
Background
I have a Drupal install accessing a large users database (~200k rows) and my "People finder" functionality needs to access all those rows (in a random order). I don't seem to be able to ...
