LDAP v. RDBMS for large datasets

["Paul Makepeace" <Paul.Makepeace@realprogrammers.com>]

I'm curious whether anyone has any opinion/evidence of whether a fixed-length
query match "SELECT uid=xxx" would be quicker (generally, or in specific
cases) versus (uid=xxx) for large ranges of xxx, in the hundreds of millions.
No other properties of either SQL or LDAP search filters are required. Assume
LDAP-friendly high read:write ratio, no transactions, etc.

Sorry to be this vague, I'm really just after ball-park estimates, i.e one is
drastically quicker than the other or they're about the same or perhaps even
odd-OS/platform specific situations. Touchy-feely answers are fine :-)

Thanks,
Paul


--
Paul.Makepeace@realprogrammers.com
Thus spake the Master Programmer:
  "Let the programmers be many and the managers few --
    then all will
      be productive." (http://misspiggy.gsfc.nasa.gov/tao.html)