Optimizing a query with multiple IN - postgresql

Question

I have a query like this:
SELECT * FROM table
WHERE department='param1' AND type='param2' AND product='param3'
AND product_code IN (10-30 alphanumerics) AND unit_code IN (10+ numerics)
AND first_name || last_name IN (10-20 names)
AND sale_id LIKE ANY(list of regex string)
Runtime was too high so I was asked to optimize it.
The list of parameters varies for the code columns for different users.
Each user provides their list of codes and then loops over product.
product used to be an IN clause list as well but it was split up.
Things I tried
By adding an index on (department, type and product) I was able to get a 4x improvement.
Current runtime is that some values of product only take 2-3 seconds, while others take 30s.
Tried creating a pre-concat'd column of first_name || last_name, but the runtime improvement was too small to be worth it.
Is there some way I can improve the performance of the other clauses, such as the "IN" clauses or the LIKE ANY clause?

Answer 1

In my experience replacing large IN lists, with a JOIN to a VALUES clause often improves performance.
So instead of:
SELECT *
FROM table
WHERE department='param1'
AND type='param2'
AND product='param3'
AND product_code IN (10-30 alphanumerics)
Use:
SELECT *
FROM table t
JOIN ( values (1),(2),(3) ) as x(code) on x.code = t.product_code
WHERE department='param1'
AND type='param2'
AND product='param3'
But you have to make sure you don't have any duplicates in the values () list
The concatenation is also wrong because the concatenated value is something different then comparing each value individually, e.g. ('alexander', 'son') would be treated identical to ('alex', 'anderson')`
You should use:
and (first_name, last_name) in ( ('fname1', 'lname1'), ('fname2', 'lname2'))
This can also be written as a join
SELECT *
FROM table t
JOIN ( values (1),(2),(3) ) as x(code) on x.code = t.product_code
JOIN (
values ('fname1', 'lname1'), ('fname2', 'lname2')
) as n(fname, lname) on (n.fname, n.lname) = (t.first_name, t.last_name)
WHERE department='param1'
AND type='param2'
AND product='param3'

Answer 2

You generally don't have to do anything special to enable an index for it to be used with multiple IN-lists, other than keep the table well vacuumed and analyzed. A btree index on (department, type, product, product_code, unit_code, (first_name || last_name)) should work well. If it doesn't, please show an EXPLAIN (ANALYZE, BUFFERS) for it, preferably with track_io_timing turned on. If the selectivities of each of your conditions are not mostly independent of each other, that might lead to planning problems.