We need to run the schema migration manually using
"CREATE INDEX CONCURRENTLY upper_stream_name_idx ON zerver_stream ((upper(name)));"
since we need CONCURRENTLY and I seem to recall that doesn't work with South.
This significantly improves the uncached performance of get_stream()
(e.g. from 32ms to 9ms). At present, this codepath is not used
particularly heavily since we do cache the stream names and do most of
our filtering by recipient ID, but the index isn't expensive and does
provide a significant improvement in the uncached case.
(imported from commit 4d28dc2e9a02d0602861b165393d90ed18f5f4c8)
Tim Abbott