Whenever we try to develop an application with SQLite, we often get an error SQLite Database is Locked. So in this “How to” we will get to know “how to fix this Operational error code 5 using some easy methods?”
SQLite is a relational database management system which is contained in a C library. Rather being a client-server database engine it is embedded into the end-program which makes it fast and contrast to many other database systems.
SQLite Database is Locked | Operational Error Code 5
This is an Operational error which indicates that the application is handling more concurrency than the default configuration. it means that one thread has a lock on the database and other thread or process is waiting for the release of that lock.
Reasons for the Error Database is locked
SQLite_locked error has multiple reasons to occur:
- Being a lightweight database, SQLite can’t handle a higher level of concurrency.
- When trying to Insert into a table while a Select thread is active on the same table.
- When trying to perform two Select on a table at the same time in a multithread application while SQLite is not configured for that.
- An NFS locking issue is generating the SQLite_locked error.
- whenever trying to Create or Drop a table while a Select thread is going on that table.
Fact_O_Verse: SQLite_locked vs SQLite_busy
There is a huge confusion between SQLite_locked and SQLite_busy. SQLite_locked represents a situation when there is a dispute between two transactions running on the same database connection. On the other hand, SQLite_busy points to a state when two transactions are running on different database connections and they have conflicted on different processes.
How to Fix SQLite Database is Locked Error
It becomes really annoying whenever this SQLite_locked error occurs but using some of the mentioned methods, you can easily unlock SQLite database.
1. By Creating Backup Having No Locks:
To remove the error code 5 from SQLite database, the best way is to create a backup of the database having no locks. When the backup is created, just replace the original one with the backup copy. Just execute the below script to do so:
Note:- Here, db.SQLite is meant to be a SQLite database file.
Sqlite> .backup main backup.Sqlite
In the same directory, you will get the newly created backup file. Now just swap the old file with this new file and execute the further script.
$mv .db.Sqlite old.Sqlite
$mv backup.Sqlite .db.Sqlite
After the execution of the above script just check that the database is open allowing for both Read and Write. Then delete the old database file and you are good to go. This way you can easily fix SQLite Database is locked error.
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2. Rewrite The Code:
SQLite is a “lite” database for real-world implementation. Whenever we try to make the database handle concurrency more than the default configuration we face errors. So rewriting the code for reducing concurrency can help to unlock SQLite Database. By doing so you can also ensure that the transactions are not long-lived.
3. Increase Default Timeout:
If a transaction takes too much time then it can make other threads block from accessing the database. In the worst-case scenario, several threads can deadlock while waiting for each other’s completion. To remove this issue, SQLite has a lock timeout. If it detects that a thread is waiting for a lock for more than default time(5 seconds), it stops the process and we face SQLite database is locked error.
To remove this error, you can increase the timeout value from the timeout database option.
The Automated Way:
The real trouble with the database is this error. As I’ve mentioned there are multiple ways to unlock SQLite Database but each of the steps got its own pros and cons. It becomes more dreadful if the database gets altered or deleted during these processes. So it’s better to go for an automated solution which can do the job without any data loss. My recommendation is to go for the SQLite Database Repair Utility which can easily fix most of the database errors with zero data alterations.
As I’ve given you all the possible reasons which can create blunders in your application and database. So try to keep all those reasons in your mind while working with the SQLite database and if you are up to fix your database then please don’t forget to take a backup first because these processes can ruin your data as well. If you have any other query regarding the process to fix SQLite Database is locked error then do let me know, I’ll do my best to help you out. Hope your issue gets resolved.