I have a DB table with 25M rows, ~3K each (i.e. ~75GB), that together with multiple indexes I use (an additional 15-20GB) will not fit entirely in memory (64GB on machine). A typical query locates 300 rows thru an index, optionally filters them down to ~50-300 rows using other indexes, finally fetching the matching rows. Response times vary between 20ms on a warm DB to 20 secs on a cold DB. I have two related questions:
1. At any given time how can I check what portion (%) of specific tables and indexes is cached in memory?
2. What is the best way to warm up the cache before opening the DB to queries? E.g. "select *" forces a sequential scan (~15 minutes on cold DB) but response times following it are still poor. Is there a built-in way to do this instead of via queries?a
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-- Shaul