Thanks, but how can I inspect the revisions in code? I'd need to provide some special markers on the ones I don't want to surround in a transaction.
pt., 10 sie 2018 o 20:50 Mike Bayer <mike...@zzzcomputing.com> napisał(a): > On Fri, Aug 10, 2018 at 2:00 PM, Michał Bultrowicz > <michalbultrow...@gmail.com> wrote: > > Hey! > > > > What approach would you recommend if we want to run some revisions > outside > > of a transaction, but then run the other ones normally? > > > > Let me illustrate that. Let's say we have revisions 1,2,3,4,5. The > database > > is currently at revision 1, so we need to run 2-5. The problem is that 4 > is > > an operation that can't be in a transation, specifically CREATE INDEX > > CONCURRENTLY from Postgres (synchronous creation of the index would block > > writes to a table, which is unacceptable in production). > > So we'd like to run, 2 and 3 in a transaction, then do 4 outside of a > > transactionand wait for it, then run 5 in a transaction. > > > so you want to set transaction_per_migration: > > > http://alembic.zzzcomputing.com/en/latest/api/runtime.html?highlight=transaction_per_migration#alembic.runtime.environment.EnvironmentContext.configure.params.transaction_per_migration > > you're still safe if 1,2,3 or 5 fail since they are in their own > transaction and it will stop at that migration if a problem happens. > > then in migration 4, inside the migration script get a separate > connection, which has to be an ".autocommit' connection with psycopg2: > > with > op.get_bind().engine.connect().execution_options(isolation_level='AUTOCOMMIT') > as conn: > conn.execute("CREATE INDEX CONCURRENTLY") > > > > > > > > > > > In run_migrations_online (we don't use offline) there's this bit > > with sql_engine.connect() as connection: > > with context.begin_transaction(): > > context.run_migrations() > > > > Can we get access to the list of revisions here and bundle them up > however > > we want? > > > > Best regards, > > Michał Bultrowicz > > > > -- > > You received this message because you are subscribed to the Google Groups > > "sqlalchemy-alembic" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to sqlalchemy-alembic+unsubscr...@googlegroups.com. > > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy-alembic" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy-alembic+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy-alembic" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy-alembic+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
