On 3/10/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Hello, > > I need to run some SELECT queries that take a while (10+ minutes) to > complete, and I'm wondering about the isolation about the results I get. > More precisely, while my SELECT is running, the DB is being updated by > another application, and I am wondering which, if any, data changes my SELECT > will see. > > Example: > If I start my SELECT at 10:00, and it finishes at 10:10, will my results > include data that was inserted between 10:00 and 10:10? > Similarly, will my result include data that was updated between 10:00 and > 10:10? > The same question for data that was deleted during that period. >
no > If it matters, my SELECT runs from psql client, while concurrent inserts, > updates, and deletes are executed from a separate application (webapp). > doesn't really matters > For my purposes in this case I need the SELECT to get the results that > represent data right at the beginning of the query - a snapshot. I read > this: http://www.postgresql.org/docs/8.1/static/transaction-iso.html and it > looks like this is the default PG behaviour (READ COMMITTED) > yes, it is > Question: > If I do not explicitly START TRANSACTION before the SELECT, will this READ > COMMITTED XA behaviour still be in effect? > yes. all statements not executed inside a transaction block are in an implicit transaction > Thanks, > Otis > > -- regards, Jaime Casanova "What they (MySQL) lose in usability, they gain back in benchmarks, and that's all that matters: getting the wrong answer really fast." Randal L. Schwartz ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
