DISTRIBUTED BY uses
hash distribution with one or more columns declared as the distribution
key. For the most even data distribution, the distribution key should
be the primary key of the table or a unique column (or set of columns).
If that is not possible, then you might choose DISTRIBUTED RANDOMLY,
which sends the data round-robin to the segment instances. If a value
is not supplied, then hash distribution is chosen using the primary
key (if the table has one) or the first eligible column of the table
as the distribution key.
DISTRIBUTED_BY can be
submitted as shown above or within the DBCREATE_TABLE_OPTS= table
option. Here is an example of how it is specified in DBCREATE_TABLE_OPTS=:
dbcreate_table_opts='distributed by ("b")'