Hi,
Why would we support HASH partitions?
If you did, the full syntax for hash clusters should be supported.
In MySQL, Oracle, the syntax for HASH partitions seems to be similar to the one mentioned. I do not know much about hash clusters though.
If we do the CHECK clauses like that then we still have don't have a
guaranteed non-overlap between partitions. It would be easier to use
Oracle syntax and then construct the CHECK clauses from that.
Again Oracle, MySQL use "VALUES LESS THAN (expr)" format for RANGE partitions. So you mean that they end up creating ranges like "MININT - Range1", "Range1+1 - Range2" etc for each of the partitions?
I think Postgres users are used to the CHECK clauses and I still feel that the onus of distinct partitions lies on the partition creator.
Also, the syntax needs to be fairly complex to allow for a mixture of
modes, e.g. range and list partitioning. That is currently possible
today and the syntax for doing that is IMHO much simpler than the Oracle
"simple" way of specifying it.
Subpartitioning is not being targeted right now, but could be put on the TODO list for further enhancements.
An alternative is to provide a partitioning function which decides which
partition each values goes into.
PARTITION FUNCTION which_partition(date_col)
The partition function must return an unsigned integer > 0, which would
correspond to particular partitions. Partitions would be numbered 1..N,
and named tablename_partM where 1 <= M <= N.
The input and contents of the partition function would be up to the
user. e.g.
CREATE FUNCTION range_partition(date date_col)
{
if (date_col < D1)
return 1;
else if (date_col < D2)
return 2;
else if (date_col < D3)
return 3;
return 4;
}
Doing it this way would allow us to easily join two tables based upon a
common partition function.
In time, I would suggest we support both ways: declarative and
functional.
Till now, we are going the declarative way.
Regards,
Nikhils
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EnterpriseDB
http://www.enterprisedb.com
