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This article shows you whether multiple applications in SQLite can access a single database file at the same time, the content is concise and easy to understand, it can definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

Multiple processes can open the same database at the same time. Multiple processes can execute SELECT at the same time. However, only one process can make changes to the database at any time.

SQLite uses read / write locks to control access to the database. (under Win95 / 98 / ME, there is a lack of support for read-write locks, but probabilistic simulation is used.) Note, however, that this locking mechanism may not work properly if the database file is saved on the NFS file system. This is because many NFS implementations break the fcntl () file lock. If multiple processes may try to access the file at the same time, you should avoid placing SQLite database files on NFS. On Windows, Microsoft's documentation says that if you are not running the Share.exe daemon, locking may not work under the FAT file system. People with a lot of experience with Windows have told me that file locking for network files is very wrong and unreliable.

We know that no other embedded SQL database engine supports as much concurrency as SQLite. SQLite allows multiple processes to open the database file at once and to read the database at one time. When any process wants to write, it must lock the entire database file during the update. But it usually only takes a few milliseconds. Other processes just wait for the authors to complete and then continue their business. Other embedded SQL database engines typically allow only a single process to connect to the database at one time.

However, client / server database engines, such as PostgreSQL,MySQL or Oracle, typically support higher levels of concurrency and allow multiple processes to write to the same database at the same time. This is possible in client / server databases because there is always a well-controlled server process that can be used to coordinate access. If your application requires a lot of concurrency, you should consider using a client / server database. But experience has shown that most applications require far less concurrency than designers think.

When SQLite attempts to access a file locked by another process, the default behavior is to return SQLITE_BUSY. You can adjust this behavior from C code using the sqlite3_busy_handler () or sqlite3_busy_timeout () API functions.

The above is whether multiple applications in SQLite can access a single database file at the same time. Have you learned the knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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