SELECT statements do in fact use the transaction system. So it has been brought to my attention by "elegant dice" that the SQLite documentation statement I quote above is misleading. When it doesn't have to do this, you get a performance boost. Normally after each transaction, sqlite will document the transaction in the journal. But disabling the log is a good way to increase performance as well. Lastly, disabling journaling via PRAGMA journal_mode = OFF does not disable transactions, only logging. Any command that changes the database (basically, any SQL command other than SELECT) will automatically start a transaction if one is not already in effect." "No changes can be made to the database except within a transaction. Otherwise sqlite will automatically put the two insert statements in separate unique transactions.Īccording to the "SQL as Understood by SQLite" documentation concerning transactions: What the author of the blog might have been trying to say, is that if you plan to do an INSERT, then a SELECT, then another INSERT, then it would increase performance to manually wrap these statements in a single transaction. Be sure to read the de facto SO question on improving sqlite performance. What many don't understand is that unless you manually BEGIN and COMMIT a transaction, each statement will be automatically put in their own unique transaction. Transactions are always and only used when making changes to the database, and transactions cannot be disabled. I'm not sure where the blog is getting this information, but wrapping SELECT statements in transactions does nothing. Once an explicit transaction has been opened, it will remain open until it is committed or rolled back.įollowing is the syntax of the SQLite BEGIN command."Use transactions – even if you’re just reading the data. The BEGIN command is used to start or open a transaction. It’s not possible for us to use these commands to CREATE and DROP tables operations because those are auto-commit in the database. We can use these commands only when we are performing INSERT, UPDATE, and DELETE operations. ROLLBACK – It will rollback the complete transaction.COMMIT – It will commit the transaction that means all the changes saved to the database.In case if we want to control these transactions to maintain data consistency and to handle database errors then by using following commands we can disable auto-commit mode and explicitly start the transactions based on our requirements. Generally, the SQLite is in an auto-commit mode that means SQLite automatically starts a transaction for each command, process, and commit the transaction changes automatically to the database. In case, if any error occurred while executing these SQLite statements then the complete transaction will be rollbacked. If all these T-SQL statements executed successfully without having any errors then the transaction will be committed and all the changes made by the transaction will be saved to the database permanently. Generally in SQLite transaction means it’s a set of T-SQL statements that will execute together as a unit like a single T-SQL statement. Here we will learn how to control SQLite Transactions using begin, commit, and rollback commands with examples.
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