How to SELECT FOR UPDATE?

[timowest]

Hi,

How can I generate a "SELECT FOR UPDATE" SQL query using querydsl-sql?

Thanks,
Gili

timowest

You can use the MySQLQuery class and call for forUpdate() or alternatively use the following invocation in SQLQueryImpl


query.addFlag(Position.END, "\nfor update ");

cowwoc

Hi Timo,

I'm using H2 so I'm afraid this won't help me. I ended up using READ_REPEATED transaction isolation as a workaround for now. Is it possible to introduce this feature into the API in a portable way? Or is it too database-specific and I should file a specific RFE for H2 support?

I'm also beginning to think that I'm better off using READ_REPEATED transaction isolation than SELECT ... for UPDATE because when I need to establish a read-lock on a table, I tend to need to do the same for the remaining tables (which READ_REPEATED does for me automatically).

Thanks,
Gili

timowest

You should manage transaction isolation levels outside of Querydsl queries.

If you need this on a per query basis than you probably need to get in contact with the H2 guys, if something similar is not yet available.

cowwoc

Timo,

I believe you misunderstood me. I was saying that H2 *does* support SELECT ... FOR UPDATE but that the H2 dialect in Querydsl did not.

That being said, I don't need it for now because I decided to use READ_REPEATED transaction isolation for now.

Gili

timowest

If the H2 syntax for Select for update is similar to that of MySQL, you can use the addFlag code I posted.