Alvaro Herrera wrote:
> No amount of tinkering is going to change the fact that a seqscan is the
> fastest way to execute these queries. Even if you got it to be all in
> memory, it would still be much slower than the other systems which, I
> gather, are using columnar storage and thus are perfectly suited to this
> problem (unlike Postgres). The talk about "compression ratios" caught
> me by surprise until I realized it was columnar stuff. There's no way
> you can get such high ratios on a regular, row-oriented storage.
One of the "good tricks" with Postgres is to convert a very wide table into a set of narrow tables, then use a view to
createsomething that looks like the original table. It requires you to modify the write portions of your app, but the
readportions can stay the same.
A seq scan on one column will *much* faster when you rearrange your database this way since it's only scanning relevant
data. You pay the price of an extra join on primary keys, though.
If you have just a few columns in a very wide table that are seq-scanned a lot, you can pull out just those columns and
leavethe rest in the wide table.
The same trick is also useful if you have one or a few columns that are updated frequently: pull them out, and use a
viewto recreate the original appearance. It saves a lot on garbage collection.
Craig