Simon Riggs wrote:
in those cases you are really just maintaining the indexes for partitioning
purposes. On older data it may be desirable not to have lots of indexes,
or at least use their resources on the indexes they really do want.
Also, if you have a List partitioned table where all rows in that table
have a single value, then you maintain an index for no reason other than
partitioning. Thats an expensive waste.
Simply put, adding a constraint is faster and cheaper than adding an
pointless index. CE gives people that option.
It seems with a partial index that whose partial index condition
specifies a range outside that of a partition would make the expense
much cheaper.
For example, if I created a couple partial indexes
ON sales_2005(year) WHERE year<2005
ON sales_2005(year) WHERE year>2005
I would think it would be a very cheap index to maintain
(they'd be very small because they're empty, I'd think)
and give many of the same benefits for excluding tables
as a non-partial index on year would have given.
Ron
I like the other features Simon mentioned, though, that sound like
they're based on these constraints.
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TIP 6: explain analyze is your friend
