Dear Postgres community, I'm looking for some help to manage queries against two large tables.
Context: We run a relatively large postgresql instance (5TB, 32 vCPU, 120GB RAM) with a hybrid transactional/analytical workload. Data is written in batches every 15 seconds or so, and the all queryable tables are append-only (we never update or delete). Our users can run analytical queries on top of these tables. We recently came across a series of troublesome queries one of which I'll dive into here. Please see the following gist for both the query we run and the \d+ output: https://gist.github.com/mewwts/9f11ae5e6a5951593b8999559f5418cf. The tables in question are: - `ethereum.transactions`: 833M rows, partitioned, 171M rows after WHERE - `uniswap_v2."Pair_evt_Swap": 12M rows, not partitioned, 12M rows after WHERE The crux of our issue is that the query planner chooses a nested loop join for this query. Essentially making this query (and other queries) take a very long time to complete. In contrast, by toggling `enable_nestloop` and `enable_seqscan` off we can take the total runtime down from 16 minutes to 2 minutes. 1) Vanilla plan (16 min) : https://explain.depesz.com/s/NvDR 2) enable_nestloop=off (4 min): https://explain.depesz.com/s/buKK 3) enable_nestloop=off; enable_seqscan=off (2 min): https://explain.depesz.com/s/0WXx How can I get Postgres not to loop over 12M rows? Let me know if there is anything I left out here that would be useful for further debugging. -- Mats CTO @ Dune Analytics We're hiring: https://careers.duneanalytics.com
