Re: Anyone for SSDs?

>> Heck, even RAM isn't 1.0.  I'm also involved with the Redis project,
>> which is an in-memory database.  Even for a pure-RAM database, it turns
>> out that just using linked lists and 100% random access is slower than
>> accessing page images.
> 
> That's a slightly different problem, though.  Sequential vs. random
> access is about whether fetching pages n, n+1, n+2, ... is faster than
> skipping around, not whether accessing fewer pages is faster than
> more.

It's not though.  Redis stores stuff as lists and sets, so it actually
does a lot of sequential access of data.  Like if people are accessing
an ordered set, they're usually pulling the whole thing.  It turns out
that *even in RAM* storing stuff in an ordered fashion on data "pages"
is more efficient than just using pointers.

--                                  -- Josh Berkus                                    PostgreSQL Experts Inc.
                        http://www.pgexperts.com