Q: Structured index - which one runs faster?

Hi all,

sorry for reposting this to the lists, but I feel I posted this at the
wrong time of day, since now a lot more of you gurus are reading, and I
really need some knowledgeable input... thanks for consideration :)

I have a question concerning table/key layout.

I need to store an ID value that consists of three numerical elements:
- ident1 char(5)
- ident2 char(5)
- nodeid int4

I need an index on these columns. Insert, delete, and lookup operations
this in this need to be as fast as possible. Now I have two options:

(a) creating an index on all three columns, or
(b) create a single varchar column combining all three components into a
single string, like "ident1:ident2:nodeid" and indexing this column only.

There will be a couple of million rows in this table, the values in
question are not unique.

Which would be faster in your opinion? (a) or (b)?

Thanks for any insight,

--
>O Ernest E. Vogelsinger
(\) ICQ #13394035
^ http://www.vogelsinger.at/

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--
>O Ernest E. Vogelsinger
(\) ICQ #13394035
^ http://www.vogelsinger.at/