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1. #Net no exception thrown for deadlock sql how to#
2. #Net no exception thrown for deadlock sql update#
3. #Net no exception thrown for deadlock sql manual#
4. #Net no exception thrown for deadlock sql code#

As any query that must update ALL rows, is going to lock the entire table, thus preventing a second user from running a similar transaction (regardless how fast it is – as eventually it will slow down as the number of records grow over time). IMO, that is probably a design issue that should be analyzed to see how feasible it would be to remove that calculated column and do the calculation in the getter of that object’s property.īut seeing how, it is what it is, this will not be an easy to avoid situation when you have multiple users invoking similar transactions against your database. Hmm, you have to update all rows for a table because it stores a calculated result? I’ve never been much of a fan for storing calculated results (especially ones that have to be updated routinely unless used for reporting only purposes that can run off hours, or that could be updated off hours instead of in real-time). Now there are very few problematic queries and I’ll be trying to improve them but what I’m asking here is more about dealing with deadlocks and restarting the transactions in the application code. I managed to solve this by moving the update after the end of the transaction.

#Net no exception thrown for deadlock sql code#

Needless to say, writing a better query and updating the code for that situation solved that one.Īre you saying that in your case SELECT queries were causing deadlocks? I’ve never seen a SELECT causing a deadlock in my case - it’s always insert, update or delete.įor example, there was an insert to the product table, then an update on all rows in this table to update a calculated column - the update takes about 1 second but if another thread tries to do the same - insert and then do the update - while the first update is still running the deadlock occurs. Once we did that, our deadlocks disappeared quickly, but we still encountered a few of them, which I later tracked down to the code requesting data from the same set of tables repeatedly within a loop (600 times!).

Any ideas?īecause of sheer volume, and the reporting we were doing during business hours, at my prior job, we made 98% of our SELECT queries to utilize WITH(NO LOCK), but MySQL does have similar commands. However, this seems ugly and I’d have to litter a lot of my code with mechanisms for restarting transactions in places that should not (I think) have to deal with such issues.

saveWithTransaction() ) and in the original method (save() ) use a for loop to run the transaction method and catch any DeadlockExceptions and retry if necessary. What would be the best method to do this? The only solution I can see is to move the code from each method that uses transaction to another method (e.g. some other more db operations involving INSERT, UPDATE and DELETEĮach of the above operations can potentially end up in deadlock and I’d have to start from scratch. DELETE old entries in some other table. UPDATE a table which holds products indexed for search engine INSERT a few rows to product_accessory table INSERT a few rows to product_category table I have to start the whole transaction again. When I start transaction, insert a new row and the next query causes deadlock then the new row can be lost and I can’t simply retry the second query and continue. This was easy to implement because I have a central Db class but it does only retry a single query not the whole transaction. One thing I have done so far is I have made the query() method in my Db class detect deadlock error #1213 and retry the query up to 3 times.

#Net no exception thrown for deadlock sql how to#

So here’s my question - how to restart transactions elegantly in PHP? So I am now at this stage - deadlocks happen rarely but still they do happen and I want to be prepared for that.

#Net no exception thrown for deadlock sql manual#

Moreover, the MySQL manual says that deadlocks are a natural thing in complex databases and the client simply needs to restart the transaction and if this doesn’t occur often then this doesn’t pose the problem. that are executed within various transactions and coordinating all those queries so that they do not cause deadlocks in any used scenario seems like an almost impossible task. However, as the application grows more and more complex it’s difficult to guarantee deadlock-free transactions since there are many different functions, methods, modules, stored procedures, etc. I’ve searched information on deadlocks and I know there are certain steps that can be taken to minimize their occurrence like updating in a certain order, etc. But sometimes a query in a transaction ends up with this error: Deadlock found when trying to get lock try restarting transaction #1213 I like to enclose portions of SQL updates, inserts and deletes in a transaction to ensure the operation is atomic and I don’t end up with partially executed action if something goes wrong. More and more often I come across a problem of deadlocks in mysql.