PostgreSQL 9.5: UPSERT, Row Level Security, and Big Data

Re:PostgreSQL 9.5: UPSERT, Row Level Security, and Big Data by jeffdavis on Thursday January 07, 2016 @09:49AM (#10858164)

Normal views aren't designed for security. There are a number of ways that they can "leak" information that is supposed to be hidden.

The reason is that the optimizer reorders operations. So, a tricky person can write the query in a way that, for example, throws a divide-by-zero error if someone's account balance is within a certain range, even if they don't have permission to see the balance. Then they can run a few queries to determine the exact balance.

RLS builds on top of something called a "security barrier view" which prevents certain kinds of optimizations that could cause this problem.

It also offers a nicer interface that's easier to manage.

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Re:PostgreSQL 9.5: UPSERT, Row Level Security, and Big Data by Sanddancer on Thursday January 07, 2016 @12:10PM (#10859160)

I may be wrong in the level of separation that pgsql provides in such situations, but it appears that a materialized view offers another level of isolation that would make such leaks more difficult to handle.

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