Lock/unlock a database table

Shyam_Katti

The documentation for locking a database table is not provided in Vertica 5.1.x. When I tried 'LOCK TABLE ', it worked and no other was able to access. Funny, but now I am not able to come up with a command that would unlock the same table :-). I have tried: unlock table and quite few other crazy combinations. Why is this command not specified in the documentation? and how do I unlock the table?

Bhawana

Hi Shyam, You should be able to either commit or rollback to release the lock. Thanks Bhawana

Navin_C

Conitnuing the above topic, How does Lock table come in use. I checked it on my end, Locked a table "K" through user a user a can select, insert (read/write) into table "K" at the same time user b can also select /insert (read/write) into table "K" So how does it help or function.

Bhawana

Hi Navin, It seems like table "K" is not locked. You can check if that table is locked or not from the following command: select node_names,object_name,lock_mode,lock_scop from LOCKS; Try this one: 1. Open two session at the same time. 2. In session one, run your sql:select * from "table name" for update; 3. In session two, run the same query and it should hang in this session because that table is locked. 4.Back in session one, you should be at vsql prompt - if you type commit, you should then see session 2 return to the vsql prompt(or results first,then vsql) Thanks Bhawana