This question already has answers here:
How can I undo a mysql statement that I just executed?
(6 answers)
cancel a transaction in MySQL InnoDB instead of commit or rollback
(1 answer)
Closed 3 years ago.
ACID properties of Transaction Properties says that either full transaction occurs or nothing occurs. Lets say I want to stop a happening Transaction.
What is the query for stopping a Transaction before it successfully completed?
Related
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How to set a maximum execution time for a mysql query?
(5 answers)
Closed 4 years ago.
Is there any configuration setting using which long running query can be killed automatically in mysql?
yes you can ! There is two ways of doing it.
In query
It sets a timeout in milliseconds.
SELECT /*+ MAX_EXECUTION_TIME(1000) */ status, count(*) FROM articles GROUP BY status ORDER BY status;
With server variables
SET SESSION MAX_EXECUTION_TIME=2000;
SET GLOBAL MAX_EXECUTION_TIME=2000;
These set a session-wide and global timeout.
I took the answer from this website.
I hope it helped.
This question already has answers here:
Lock mysql table with php
(4 answers)
Closed 4 years ago.
I have multiple independent processes, Scripts A and B, that each access the same table. I would like to Script A to read a record from the table then maybe modify that record (or maybe not).
The thing is that I need to keep Script B from accessing that particular record In the midst of that. Is there a manual lock perhaps? Something that will keep Script B out for just those few milliseconds?
Thanks
You don't want to lock the entire table right?
For InnoDB table a select...for update should do, it will lock the record (just add for update at the end of the query).
On your script A:
Create a transaction
Do a select for update
If you want to update the record, do so.
Commit the transaction when you finish.
On your script B do a select for update as well, it will wait until script A release the lock.
This question already has answers here:
Automatic Rollback if COMMIT TRANSACTION is not reached
(5 answers)
Closed 5 years ago.
I'm using InnoDB 5.6.35, and I have a question regarding the correct way to implement MySQL transaction. If I implement the following send it to MySQL in one statement:
START TRANSACTION;
SQL-Statement 1;
SQL-Statement 2;
...
COMMIT;
Question: Does MySQL automatically issues the Rollback if one of the SQL statements fails? The behavior I've seen is that it looks like MySQL does not commit with the above statements when it encounters a failed operation (even Rollback is not called in my program), but I am not too sure after reading some postings. Do I have to wrap the codes in a stored procedure as suggested by others, and call "Rollback" explicitly in my code?
Can someone help me to clarify this?
https://dev.mysql.com/doc/refman/5.5/en/innodb-error-handling.html
Just on some cases it will rollback only the statement that failed.
If you run out of file space in a tablespace, a MySQL Table is full
error occurs and InnoDB rolls back the SQL statement.
A transaction deadlock causes InnoDB to roll back the entire transaction.
A duplicate-key error rolls back the SQL statement
A row too long error rolls back the SQL statement.
Other errors are mostly detected by the MySQL layer of code (above the InnoDB storage engine level), and they
roll back the corresponding SQL statement
This question already has answers here:
Is there any way to rollback after commit in MySQL?
(3 answers)
Closed 7 years ago.
Can we undo more than one change in mysql? I deleted some rows and did a select * to see the table. I saw ROLLBACK but I guess it only reverts the action by last query. Can I undo deleting those rows?
If there is no way to undo more than one changes, is there a way to view last edited table and undo change done before viewing it? Also, are changes before last query committed(even when AUTOCOMMIT is 0)?
the solution for the issue is that please heck that you binary logs has been activated in your server, if you have binary logs active on your server you can use mysqlbinlog
After taht generate a sql file with it
mysqlbinlog binary_log_file > query_log.sql
then find your missing rows.If not you have to keep Backup your DB from next time
From the reference manual: http://dev.mysql.com/doc/refman/5.1/en/commit.html
By default, MySQL runs with autocommit mode enabled. This means that
as soon as you execute a statement that updates (modifies) a table,
MySQL stores the update on disk to make it permanent.
This means that after you have deleted your records (and committed explicitly or implicitly), you cannot roll them back.
Rollback is a kind of undo for things which change data in tables, however in order to use you have to either:
turn off auto commit and use commit statements explicitly.
make your changes in transactions
there are statements which cause implicit commits: link
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Restarting transaction in MySQL after deadlock
(4 answers)
Closed 8 years ago.
I have a situation where 2 transactions create a mysql deadlock.
The following error is fired : Deadlock found when trying to get lock; try restarting transaction
If I'm correct, this error means that mysql deadlock timeout is expired, and mysql try to do something to removes this deadlock.
What isn't clear for me is what means try restarting transaction ? How a transaction can be "restarted" ?
What happens to the 2 locked transactions ? Are they both canceled (roll-backed) ? Or is it just one of them that is canceled so the lock can be released.
Thanks in advance
There is no deadlock timeout (though there are lock timeouts). If a deadlock is detected, no amount of time will resolve it, so MySQL reacts immediately.
MySQL will roll back one or more transactions until the deadlock is resolved.
From MySQL docs:
InnoDB tries to pick small transactions to roll back, where the size
of a transaction is determined by the number of rows inserted,
updated, or deleted.
It is up to your application that is making the SQL call to retry the transaction.
MySQL has some recommendations in its documentation How to Cope with Deadlocks.
If you wish to try to avoid the deadlock and are having trouble understanding the cause of the deadlock, I recommend starting another question, and posting the complete affected queries and schema, and ideally the deadlock report from SHOW ENGINE INNODB STATUS.