KITFORMA · EDITORIAL ANSWER
Why does LOWER(email) not use my ordinary email index?
KitForma editorial guide. An index on the raw column is different from an index on an expression applied to that column. The planner needs a compatible access path.
Step-by-step answer
An index on the raw column is different from an index on an expression applied to that column. The planner needs a compatible access path.
If case-insensitive lookup is the contract, consider an expression index on
lower(email) and use the same expression in queries. Review collation and uniqueness requirements before migrating. Test mixed-case values and existing duplicates under the chosen normalization. Do not assume lowercasing is an internationally correct identity rule for every kind of text. Expression indexes also add maintenance work to writes, so measure the actual lookup pattern before creating many variants.Sources and verification
Sources checked:
Scope: This editorial guide is based on the cited sources and tool behavior. A forum question or a query observed for our site does not establish market search volume, low competition, guaranteed rankings or inadequate answers elsewhere.
This editorial answer was prepared by KitForma with AI assistance. It is not presented as a real member question or an independent user review. Check the sources and the result with your own file; report corrections in the discussion.