CODEWITHSUNDEEP
mysql
atlau
atlau

Reputation: 971

Is it possible to execute a select query by hand, that will not block other queries?

The problem is that if I execute a select that takes minutes, all other queries are blocked in my application while my select is running, what I obviously don't want.

I wanted to see how many rows I have where a column is not NULL, in a myisam table that has 1.5 million rows, 10 GB in size. But the disk is very slow, this is why it takes so long.

select count(*) from table where column is not null;

Is it possible to run a query like this for minutes, while being able to run other queries?

Even if there is a way to run parallel queries, I suspect the slow disk will still be a problem, causing other queries to become unbearably slower.

Upvotes: 2

Views: 580

Answers (1)

Vivek Viswanathan
Vivek Viswanathan

Reputation: 1963

you can avoid locking by setting the isolation level to read uncommitted in mysql.

SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ;

select count(*) 
from table
where column is not null;

SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ ;

Upvotes: 4

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