#Sqlite transaction increased speed manual

When I first ran the new garbage collector on my four year-old 2.7GB SQLite database, it detected a tremendous number of emails to remove-almost 50,000 messages. (If you’re interested in the problem and why Geary didn’t simply delete an email when it was not visible in a mail folder, the original ticket is a good place to start.) It was a classic problem of garbage collection and reference counting.

The long and short of it is, prior to this commit, Geary never deleted emails from its internal SQLite database, even if they were deleted on the server. Let's start another transaction and delete records from the table having age = 25 and finally we use COMMIT command to commit all the changes.The week before Christmas I hunkered down and took on a nagging issue in Geary I’m almost embarrassed to discuss. Now, if you check COMPANY table, it still has the following records − Sqlite> DELETE FROM COMPANY WHERE AGE = 25 Then, use ROLLBACK command to undo all the changes. Now, let's start a transaction and delete records from the table having age = 25. ROLLBACK command can only be used to undo transactions since the last COMMIT or ROLLBACK command was issued.įollowing is the syntax for ROLLBACK command.Ĭonsider COMPANY table with the following records. ROLLBACK command is the transactional command used to undo transactions that have not already been saved to the database. Following is the simple syntax to start a transaction.ĬOMMIT command is the transactional command used to save changes invoked by a transaction to the database.ĬOMMIT command saves all transactions to the database since the last COMMIT or ROLLBACK command.įollowing is the syntax for COMMIT command. However, a transaction will also ROLLBACK if the database is closed or if an error occurs. Such transactions usually persist until the next COMMIT or ROLLBACK command is encountered. Transactions can be started using BEGIN TRANSACTION or simply BEGIN command. They cannot be used while creating tables or dropping them because these operations are automatically committed in the database. Transactional control commands are only used with DML commands INSERT, UPDATE, and DELETE.

Isolation − Enables transactions to operate independently of and transparent to each other.ĭurability − Ensures that the result or effect of a committed transaction persists in case of a system failure.įollowing are the following commands used to control transactions:īEGIN TRANSACTION − To start a transaction.ĬOMMIT − To save the changes, alternatively you can use END TRANSACTION command. Transactions have the following four standard properties, usually referred to by the acronym ACID.Ītomicity − Ensures that all operations within the work unit are completed successfully otherwise, the transaction is aborted at the point of failure and previous operations are rolled back to their former state.Ĭonsistency − Ensures that the database properly changes states upon a successfully committed transaction. Practically, you will club many SQLite queries into a group and you will execute all of them together as part of a transaction. It is important to control transactions to ensure data integrity and to handle database errors. For example, if you are creating, updating, or deleting a record from the table, then you are performing transaction on the table.

#Sqlite transaction increased speed manual

Transactions are units or sequences of work accomplished in a logical order, whether in a manual fashion by a user or automatically by some sort of a database program.Ī transaction is the propagation of one or more changes to the database. A transaction is a unit of work that is performed against a database.