Performance of multi-column index on INSERT

Hi:

  Is the performance overhead of creating a
multi-column index greater than creating an individual
index for each column? (i.e. Is the INSERT slower for
a table with a three column index than a similar table
with three single column indices?).

   I was wondering this because according to
PostgreSQL Manual in the section on multi-columned
indexes "Multicolumn indexes should be used sparingly.
Most of the time, an index on a single column is
sufficient and saves space and time".


Thank you very much,

ludwig


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