Let's assume I have a table like so:
CREATE TABLE employees (
employeeid text not null,
name text not null
);
CREATE INDEX i_employees ON employees(lower(name));
Let's also assume that the lower() function is computationally
expensive. Now if I have a query like:
SELECT lower(name)
FROM employees
WHERE lower(name) = 'mike'
will PostgreSQL re-evaluate lower(name)? Is it necessary?
Mike Mascari
[EMAIL PROTECTED]
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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
