Paul: thanks. currently I do not need this feature from Hive QL, just need it in metastore.
you said "There exists structures for supporting this in the metastore", could you please give more details? I suppose the interface to metastore is basically classes like Table, Partition, but in the Partition API http://hadoop.apache.org/hive/docs/r0.5.0/api/org/apache/hadoop/hive/metastore/api/Partition.html I don't see any reference to schema, Yang On Thu, Jul 1, 2010 at 4:56 PM, Paul Yang <[email protected]> wrote: > There exists structures for supporting this in the metastore, but that > feature isn't in Hive yet. For example, although the metadata for partitions > include its own set of columns, parts of the code in the query processor > still read from table level metadata. > > Some evolution can occur in the form of adding columns to a table. > > -----Original Message----- > From: Yang [mailto:[email protected]] > Sent: Thursday, July 01, 2010 4:43 PM > To: [email protected] > Subject: Schema evolution? > > I read on the VLBD hive paper "Hive - A Warehousing Solution Over a > Map-Reduce Framework" > that Partitions could have different schemas : (section 3.1 MetaStore) " > Partition - Each partition can have its own columns > and SerDe and storage information. This can be used > in the future to support schema evolution in a Hive > warehouse. > " > > but the API: > http://hadoop.apache.org/hive/docs/r0.5.0/api/ > > only lists getSchema() for Table, and Partition does not have a > separate getSchema(). > > is the schema evolution feature really there? > > Thanks > Yang >
