Optimizing Postgres Count For Aggregated Select - postgresql

Question

I have a query that is intended to retrieve the counts of each grouped product like so
SELECT
product_name,
product_color,
(array_agg("product_distributor"))[1] AS "product_distributor",
(array_agg("product_release"))[1] AS "product_release",
COUNT(*) AS "count"
FROM
product
WHERE
product.id IN (
SELECT
id
FROM
product
WHERE
(product_name ilike "%red%"
OR product_color ilike "%red%")
AND product_type = 1)
GROUP BY
product_name, product_color
LIMIT
1000
OFFSET
0
This query is run on the following table
Column | Type | Collation | Nullable | Default
---------------------+--------------------------+-----------+----------+---------
product_type | integer | | not null |
id | integer | | not null |
product_name | citext | | not null |
product_color | character varying(255) | | |
product_distributor | integer | | |
product_release | timestamp with time zone | | |
created_at | timestamp with time zone | | not null |
updated_at | timestamp with time zone | | not null |
Indexes:
"product_pkey" PRIMARY KEY, btree (id)
"product_distributer_index" btree (product_distributor)
"product_product_type_name_color" UNIQUE, btree (product_type, name, color)
"product_product_type_index" btree (product_type)
"product_name_color_index" btree (name, color)
Foreign-key constraints:
"product_product_type_fkey" FOREIGN KEY (product_type) REFERENCES product_type(id) ON UPDATE CASCADE ON DELETE CASCADE
"product_product_distributor_id" FOREIGN KEY (product_distributor) REFERENCES product_distributor(id)
How can I improve the performance of this query, specifically the COUNT(*) portion, which when removed improves the query but is requisite?

Answer 1

You may try using an INNER JOIN in place of a WHERE ... IN clause.
WITH selected_products AS (
SELECT id
FROM product
WHERE (product_name ilike "%red%" OR product_color ilike "%red%")
AND product_type = 1
)
SELECT product_name,
product_color,
(ARRAY_AGG("product_distributor"))[1] AS "product_distributor",
(ARRAY_AGG("product_release"))[1] AS "product_release",
COUNT(*) AS "count"
FROM product p
INNER JOIN selected_products sp
ON p.id = sp.id
GROUP BY product_name,
product_color
LIMIT 1000
OFFSET 0
Then create an index on the "product.id" field as follows:
CREATE INDEX product_ids_idx ON product USING HASH (id);