Aidan Van Dyk <aidan@highrise.ca> writes:
> On Thu, Jul 28, 2011 at 12:53 PM, Josh Berkus <josh@agliodbs.com> wrote:
>> Second, the key-based partitioning I described would actually be
>> preferred to what you describe by a lot of users I know, because it's
>> even simpler than what you propose, which means less contract DBA work
>> they have to pay for to set it up.
> But part of the desire for "simple partitioning" is to make sure the
> query planner and execution knows about partitions, can do exclude
> unnecessary partitions from queries. If partion knowledge doesn't
> help the query plans, its not much use excpt to reduce table size,
> which isn't a hard task with the current inheritance options.
> But if the "partition" selection is an opaque "simple key" type
> function, you haven't given the planner/executor anything better to be
> able to pick partitions for queries, unless the query is an exact "key
> =" type of operation.
Right. I think the *minimum* requirement for intelligent planning is
that the partitioning be based on ranges of a btree-sortable type.
Single values is a special case of that (for discrete types anyway),
but it doesn't cover enough cases to be the primary definition.
regards, tom lane