> * Given a table with columns foo, bar, baz, with an index on (foo, bar), a query with a predicate on `bar` alone is [generally] non-sargeable. Postgres can do

> * Given a table with columns foo, bar, baz, with an index on (foo, bar), a query with a predicate on `bar` alone is [generally] non-sargeable. Postgres can do this, but it's rare, and unlikely to perform as well as you'd want anyway. The one I see many times more often than this is having one index on (foo) and one index on (bar), then querying on both foo and bar, and assuming the database uses both indexes for best performance. It can be done, even by ancient mysql, but it's most likely going to be a lot slower than expected so they're heavily biased against doing it and will most likely just choose one of the two indexes.