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Is it possible to replace count distinct inside Correlated sub-queries?

I'm trying to optimize the query bellow. The execution Plan is showing multiple sorting before aggregations (I think this is due to the count distincts in the correlated sub-queries)... Is it ...
0
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1answer
72 views

Aggregate function on subquery

I have got a SALES table that has 4 document types, and they are created with reference to each other in the following order: Offer -> Order -> Delivery -> Invoice. For each new row their ...
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0answers
25 views

How can i remove filesort for this subqueires?

This is the Query: SELECT A.* FROM messages_thread_user mtu, LATERAL (SELECT m.*, u.userName FROM messages m JOIN ...
0
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1answer
23 views

MySQL - Optimize subquery in Select, where and order by

Im running a query like below. SELECT DISTINCT c.`id` , c.`job-cat` , ( SELECT COUNT(*) FROM `jobs` j WHERE j.`mul_category` IN (c.`id`) AND j.`ending` >...
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1answer
202 views

How to optimize UPDATE with a nested SELECT subquery?

I wrote a complicated UPDATE query, and it works, but it looks menacing. Here's what I'm trying to do: In each topic user 'Bob123' posted anonymously. When you post anonymously in a topic, you get ...
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1answer
51 views

Slow Query With Subqueries

I'm still rather new to doing more than just simple selects in mysql and I'm trying to optimize a rather large query. I was wondering if anyone who's been doing this for a while has any guidance on ...
0
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1answer
389 views

MYSQL join on subquery optimization

This is a distilled version of the query that I am trying to run: SELECT * FROM table1 t1 INNER JOIN (SELECT * FROM table2 WHERE foo = 'bar') t2 ON t1.id = t2.id; The above query is incredibly slow ...
0
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2answers
45 views

Which query performs better when searching a row where a column has maximum?

Consider a simple table for example purposes: person(name varchar, age int) I have a task to retrieve the oldest person. Which query is better in general for such problems? Query 1: criteria with ...
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0answers
52 views

Subquery optimization

I was reading through this article - http://explainextended.com/2009/09/18/not-in-vs-not-exists-vs-left-join-is-null-mysql/ I am working with an existing design. What I want is to be able to select ...
-1
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2answers
169 views

Optimize query or split in two queries and process result separately?

I have this DB schema: As you may notice already there is no relationship between tables and won't be on the future. If I run the following queries I will get a lot of rows per table: SELECT COUNT(*)...