Can someone confirm a suspicion for me ?
I have a moderately sized table (20+ columns, 3MM rows) that tracks "tags".
I have a lower(column) function index that is used simplify case-insensitive
lookups.
CREATE INDEX idx_tag_name_lower ON tag(lower(name));
I have a few complex queries that need to join back to this table (via the `id`
primary key) and sort on `lower(name)`.
I'm not selecting `lower(name)`, just using it for an order-by.
The only way I seem to be able to avoid a Sequential Scan and run an index-only
scan is with another index -- this one specifically (and I've run queries
against 8 index permutations):
CREATE INDEX idx_tag_joins ON tag(id, name_display);
Am I correct in observing that the value of a function index can't be used for
sorting ?
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