avoid repeating condition in select query - sql

Question

I have the following query to be executed on postgresql
SELECT COUNT(DISTINCT id_client) FROM contract c
INNER JOIN bundle b ON c.bundle_id = b.id
INNER JOIN payment_method pm ON pm.id = c.payment_method_id
WHERE country_id=1 AND b.platform_id=1 AND pm.name <> 'RIB'
AND CONDITION_1
AND id_client NOT IN (
SELECT id_client FROM contract c1
INNER JOIN bundle b1 ON (c1.bundle_id = b1.id)
INNER JOIN payment_method pm1 ON pm1.id = c1.payment_method_id
WHERE c1.country_id=1 AND b1.platform_id=1 AND pm1.name <> 'RIB'
AND CONDITION_2);
I don't like it because it's the same query repeated twice except of CONDITION_1 and CONDITION_2 (and I have another example where it's repeated 3 times).
It's also very slow as well.
I tried to rewrite it as the following:
WITH
filter_cpm AS (
SELECT * FROM contract c
INNER JOIN bundle b ON b.id = c.bundle_id
INNER JOIN payment_method pm ON pm.id = c.payment_method_id
WHERE c.country_id = 1 AND b.platform_id = 1 AND pm.name <> 'RIB'
)
SELECT COUNT(DISTINCT id_client) FROM filter_cpm
WHERE CONDITION_1
AND id_client NOT IN (
SELECT id_client FROM filter_cpm
WHERE CONDITION_2);
Now it's DRY but it's two times slower.
How can I re-write the query to have the same (or better) performance?
EDIT: I cannot join two conditions with AND. For example if CONDITION_1 and CONDITION_2 are VIP, then I want to select clients who were re-qualified from NOT VIP to VIP.

Answer 1

You can select from the common table expression twice, using an outer join:
WITH filter_cpm AS (SELECT *
FROM CONTRACT c
INNER JOIN BUNDLE b
ON b.ID = c.BUNDLE_ID
INNER JOIN PAYMENT_METHOD pm
ON pm.ID = c.PAYMENT_METHOD_ID
WHERE c.COUNTRY_ID = 1 AND
b.PLATFORM_ID = 1 AND
pm.NAME <> 'RIB')
SELECT COUNT(DISTINCT fc1.ID_CLIENT)
FROM filter_cpm fc1
LEFT OUTER JOIN filter_cpm fc2
ON fc2.ID_CLIENT = fc1.ID_CLIENT AND
CONDITION_2
WHERE fc1.CONDITION_1 AND
fc2.ID_CLIENT IS NULL
Best of luck.