Sunday, March 11, 2012

Blocking updates of a table

Hi,
I've been trying to design a way for me to issue a transaction that:
    Block all inserts on a table when row X has a certain value (call it A)
    Add a row to the table with row X containing A Add rows to another table Unblock inserts Commit transaction
Is this possible? Can anyone give me some pointers as to what to do?
Thanks in advance!

For (1) and (2)
While inserting the row that has a certain value (A), you can request a TABLOCKX. This will acquire X lock on the table and there by block other inserts by other concurrent transactions.

For (3): Is it like any other insert to another table? In that case, nothing special needs to be done

Thanks
Sunil Agarwal

|||For 3 that is what I meant.
For 1 and 2, it sounds like TABLOCKX locks the whole table exclusively (from what I can find in Books Online) - have I read it correctly? Is there any way to block other transactions from inserting rows (while the first transaction is not yet commited) when a table key column (A in my original post) is a certain value (X in my original post) - rather than just locking the whole table?
Thanks for your help!
|||For 1 and 2, it sounds like TABLOCKX locks the whole table exclusively (from what I can find in Books Online) - have I read it correctly

sunil> yes

Is there any way to block other transactions from inserting rows (while the first transaction is not yet commited) when a table key column (A in my original post) is a certain value (X in my original post) - rather than just locking the whole table?

sunila> if you only want to block inserts by other transactions under the condition you have mentioned but allow updates/selects, then there is no way.
thanks,|||I assume you only want to block Inserts but not Updates, Deletes and SELECTS.

You could try using an Insert trigger that would rollback the other transactions until a condition has been achieved.

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