BEGIN TRANSACTION ... issued commands inside transaction COMMIT or ROLLBACK -- transaction is now closed
That is, BEGIN "opens" a transaction COMMIT "closes" the transaction in progress and saves the changes made during that transaction. ROLLBACK "closes" the transaction in progress and discards the changes made during that transaction. While a transaction is "in effect", the "view" of the database is stable relative to all other CONNECTIONS to the database. Changes made to the database in transactions on OTHER CONNECTIONS are not visible, and *unless you specify otherwise* you have REPEATABLE READ isolation. Within a transaction you may nest SAVEPOINTs. Savepoints are transactions within transactions and can be viewed as a stack. If no TRANSACTION is in process then BEGIN TRANSACTION and SAVEPOINT are identical -- that is, a SAVEPOINT can only exist within a transaction and a SAVEPOINT where no transaction is in progress will start an "implicit" transaction if necessary. SAVEPOINT <xxxxx> -- create a "context" named "xxxxx" (and an "implicit" transaction if one is not already in progress) ROLLBACK TO <xxxxx> -- rollback the "context" to the state that it was in when the context was created. Do not pop the context <xxxxx> off the stack but pop any contexts off the stack that were created "after" context <xxxxx> was created. You are still in a transaction and the context <xxxxx> still exists. RELEASE <xxxxx> -- commit all the changes that occurred after the specified context to the outer context. Pop <xxxxx> from the context stack and also pop any contexts created after context <xxxxx> was declared (that is, all changes made after the declaration of the context are "moved into" the next higher context and all references to the named context and contained contexts are removed. If you have "RELEASED" the last SAVEPOINT (ie, the first on the stack) and the containing transaction was created implicitly (rather than explicitly with BEGIN), then that implicit outer transaction is also committed and no transaction is any longer in effect. If the out transaction was explicitly commenced (with BEGIN) then that transaction is still in effect and must be COMMITTED or ROLLBACKed in order to end it. --- The fact that there's a Highway to Hell but only a Stairway to Heaven says a lot about anticipated traffic volume. >-----Original Message----- >From: sqlite-users [mailto:sqlite-users- >boun...@mailinglists.sqlite.org] On Behalf Of Simon Slavin >Sent: Saturday, 2 March, 2019 16:12 >To: SQLite mailing list >Subject: [sqlite] Handling ROLLBACK > >I have run experiments in the shell tool, using different journal >modes, but I would like to know whether my observations are cannon or >just one-offs. Contributions welcome from all, especially those who >have read SQLite source code, and SQL language-lawyers whether or not >you're familiar with how other SQL implementations work. > > >Does ROLLBACK release the transaction lock on the database ? > >Does ROLLBACK cancel the BEGIN ? Or do I need to issue END ? > >Suppose ROLLBACK does not cancel the BEGIN, can a programmer reliably >issue more SQL commands, including another ROLLBACK ? Will SQLite >continue to react correctly to other ROLLBACKs, and to SQL commands >which result in "(516) SQLITE_ABORT_ROLLBACK". > > >If you think I've missed a relevant point, please don't hesitate to >bring it up. >_______________________________________________ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
