Ken Hill wrote:
> Is there a performance trade-off between column indexes and record
> inserts?
>
> I know that in MS Access there is such a trade-off. This being indexes
> make SQL queries perform faster at the cost of record insert speed. Put
> another way, the more column indexes in a table, the slower a record
> insert in that table performs.
>
> Is there a similar trade-off in PostgreSQL?
The tradeoff is made in every system. The more indexes you have on a
table, the more indexes need to be updated when you update/insert/delete
rows.
So - a unique constraint automatically implies an index in PostgreSQL
(it's how it implements its unique checks). Other than that, you should
only index those columns where you will want a small number of rows or
quick ordering.
-- Richard Huxton Archonet Ltd