Maximum (usable) number of rows in a Postgresql table

Question

I realize that, per Pg docs (http://www.postgresql.org/about/), one can store an unlimited number of rows in a table. However, what is the \"rule of thumb\" for usable numbe

Answer 1

It's not just "a bunch of tuning (indexes etc.)". This is crucial and a must do.

You posted few details, but let's try.

The rule is: Try and find the most common working set. See if it fits in RAM. Optimize hardware, PG/OS buffer settings and PG indexes/clustering for it. Otherwise look for aggregates, or if it's not acceptable and you need fully random access, think what hardware could scan the whole table for you in reasonable time.

How large is your table (in gigabytes)? How does it compare to total RAM? What are your PG settings, including shared_buffers and effective_cache_size? Is this a dedicated server? If you have a 250-gig table and about 10 GB of RAM, it means you can only fit 4% of the table.

Are there any columns which are commonly used for filtering, such as state or date? Can you the working set that is most commonly used (like only last month)? If so, consider partitioning or clustering on these columns, and definitely index them. Basically, you're trying to make sure that as much of the working set as possible fits in RAM.

Avoid scanning the table at all costs if it does not fit in RAM. If the you really need absolutely random access, the only way it could be usable is really sophisticated hardware. You would need a persistent storage/RAM configuration which can read 250 GB in reasonable time.