Bulk/batch update/upsert in PostgreSQL

Question

I\'m writing a Django-ORM enchancement that attempts to cache models and postpone model saving until the end of the transaction. It\'s all almost done, however I came across

Answer 1

I've used 3 strategies for batch transactional work:

1. Generate SQL statements on the fly, concatenate them with semicolons, and then submit the statements in one shot. I've done up to 100 inserts in this way, and it was quite efficient (done against Postgres).
2. JDBC has batching capabilities built in, if configured. If you generate transactions, you can flush your JDBC statements so that they transact in one shot. This tactic requires fewer database calls, as the statements are all executed in one batch.
3. Hibernate also supports JDBC batching along the lines of the previous example, but in this case you execute a flush() method against the Hibernate Session, not the underlying JDBC connection. It accomplishes the same thing as JDBC batching.

Incidentally, Hibernate also supports a batching strategy in collection fetching. If you annotate a collection with @BatchSize, when fetching associations, Hibernate will use IN instead of =, leading to fewer SELECT statements to load up the collections.