The Ultimate Guide to High Availability with MariaDB

Comments - SELECT

3 years, 5 months ago Tibor den Ouden
Can select for update / lock in share mode return no rows but still lock the relevant records ?

Is it possible to have select for update / lock in share mode to return no rows or an empty result set, but still lock all target records ? I use a select for update to reduce the occurrence of deadlocks but I am not interested in the returned result set. Would for instance select for update limit 0 lock all records which fulfill the conditions of the select statement but return no records ? Or is there another way to accomplish this ?

 
3 years, 5 months ago Markus Mäkelä
Re: Can select for update / lock in share mode return no rows but still lock the relevant records ?

If you know your application is the only one that modifies the records, you could use GET_LOCK to cooperatively lock the table without actually locking it.

 
3 years, 5 months ago Sergei Golubchik
Re: Can select for update / lock in share mode return no rows but still lock the relevant records ?

Try SELECT COUNT(*) FROM ... or an impossible HAVING clause

 
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