On Fri, Aug 10, 2018, 4:23 PM Michał Bultrowicz <michalbultrow...@gmail.com> wrote:
> 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. > That database code is in the migration file itself. The approach doesn't imply changes to env.py. > 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. > -- 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.