Re: Creating large database of MD5 hash values

* Jon Stewart:

> 1. Which datatype should I use to represent the hash value? UUIDs are
> also 16 bytes...

BYTEA is slower to load and a bit inconvenient to use from DBI, but
occupies less space on disk than TEXT or VARCHAR in hex form (17 vs 33
bytes with PostgreSQL 8.3).

> 2. Does it make sense to denormalize the hash set relationships?

That depends entirely on your application.

> 3. Should I index?

Depends.  B-tree is generally faster than Hash, even for randomly
distributed keys (like the output of a hash function).

> 4. What other data structure options would it make sense for me to
> choose?

See 2.

In general, hashing is bad because it destroy locality.  But in some
cases, there is no other choice.

--
Florian Weimer                <fweimer@bfk.de>
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