On Fri, Nov 12, 2010 at 12:21 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Thu, Nov 11, 2010 at 10:02 AM, Itagaki Takahiro >> <itagaki.takah...@gmail.com> wrote: >>> If we reuse type IDs of arrays for multisets, the multisets would >>> have some special typmod. For example, typmod = 0 means multiset, >>> and positive value means array with max cardinality. Note that >>> the SQL standard doesn't mention about multi-dimensional arrays. >>> So, we can use typmod = -1 as a free-size and free-dimensional >>> array for backward compatibility. > >> I would really like to see us fix our type system so that it doesn't >> require this type of awful hack. But maybe that's asking too much of >> a patch to implement this feature. > > The problem is not with the type system: as long as you give multisets > different type OIDs from arrays, everything will work fine. It will > absolutely not work to try to use typmod to make the behavior vary > like that ... but Itagaki-san knew that already.
And thus you must create a THIRD copy of every entry in pg_type. That doesn't qualify as a problem? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
