Hello, I have a program that maps a GROUP BY query to orm instances (let's say we have one called comm1). The instances have a relationship attribute: comm1.inodes. Something goes wrong when accessing comm1.inodes. SQLAlchemy generates a query that doesn't have a clause for the instance's primary key, and fetches a ton of rows from the database. The primary key doesn't appear in the result so all those rows appear identical. The Python-level results eliminate the duplicates, and yield the correct value. The problem is, the query runs like a cartesian product, and if we're unlucky it ends up consuming gigabytes of memory due to the unnecessarily repeated rows.
See https://github.com/g2p/bedup/blob/master/bedup/model.py#L204 for the declarative mapping, and see https://github.com/g2p/bedup/issues/1#issuecomment-10637878 for an example of bad generated queries. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
