Postgresql Query is taking over 30s, Failing on Heroku - node.js

Question

I have two tables (tb_accounts and tb_similar_accounts) in my PostgreSQL database.
Each record in tb_accounts has a unique id field.
And in tb_similar_accounts table, we store the relationships between accounts. We have around 10 million records in this table.
I get around 1000~4000 accounts in one of my API endpoints, and I want to get all the links from tb_similar_accounts
const ids_str = `${ids.map((id) => `('${id}')`).join(`,`)}`;
const pgQuery = `
SELECT account_1 as source, account_2 as target, strength as weight FROM tb_similar_accounts
WHERE account_1 = ANY (VALUES ${ids_str}) AND account_2 = ANY (VALUES ${ids_str})
ORDER BY strength DESC
LIMIT 10000
`;
const { rows: visEdges } = await pgClient.query(pgQuery);
This is what I'm doing here, but it's taking too much time. It takes over 30 seconds so it's failing on the Heroku server.
Limit (cost=296527.60..297597.60 rows=10000 width=30) (actual time=25075.977..25078.602 rows=10000 loops=1)
Buffers: shared hit=19 read=121634
I/O Timings: read=22104.502
-> Gather Merge (cost=296527.60..297967.40 rows=13456 width=30) (actual time=25075.975..25080.332 rows=10000 loops=1)
Workers Planned: 1
Workers Launched: 1
Buffers: shared hit=110 read=244343
I/O Timings: read=44196.556
-> Sort (cost=295527.60..295534.33 rows=13456 width=30) (actual time=25070.720..25071.022 rows=5546 loops=2)
Sort Key: tb_similar_accounts.strength DESC
Sort Method: top-N heapsort Memory: 1550kB
Worker 0: Sort Method: top-N heapsort Memory: 1550kB
Buffers: shared hit=110 read=244343
I/O Timings: read=44196.556
-> Hash Semi Join (cost=5.74..295343.04 rows=13456 width=30) (actual time=1040.173..25060.553 rows=38449 loops=2)
Hash Cond: (tb_similar_accounts.account_1 = "*VALUES*".column1)
Buffers: shared hit=63 read=244343
I/O Timings: read=44196.556
-> Hash Semi Join (cost=2.87..295096.26 rows=381936 width=30) (actual time=2.197..25039.864 rows=80874 loops=2)
Hash Cond: (tb_similar_accounts.account_2 = "*VALUES*_1".column1)
Buffers: shared hit=33 read=244343
I/O Timings: read=44196.556
-> Parallel Seq Scan on tb_similar_accounts (cost=0.00..286491.44 rows=14038480 width=30) (actual time=0.032..23394.824 rows=11932708 loops=2)
Buffers: shared hit=33 read=244343
I/O Timings: read=44196.556
-> Hash (cost=1.44..1.44 rows=410 width=32) (actual time=0.241..0.242 rows=410 loops=2)
Buckets: 1024 Batches: 1 Memory Usage: 26kB
-> Values Scan on "*VALUES*_1" (cost=0.00..1.44 rows=410 width=32) (actual time=0.001..0.153 rows=410 loops=2)
-> Hash (cost=1.44..1.44 rows=410 width=32) (actual time=0.198..0.198 rows=410 loops=2)
Buckets: 1024 Batches: 1 Memory Usage: 26kB
-> Values Scan on "*VALUES*" (cost=0.00..1.44 rows=410 width=32) (actual time=0.002..0.113 rows=410 loops=2)
Planning Time: 3.522 ms
Execution Time: 25081.725 ms
This is for 410 accounts and takes around 25 seconds.
Is there any way to improve this query? (I'm using Node.js and pg module.)

Answer 1

Check if both your tables are indexed properly i.e. try to build index on the columns which are used in joining two tables.