docs - distribution key not required to be left-subset of primary key
@@ -727,13 +727,10 @@ CREATE [ [GLOBAL | LOCAL] {TEMPORARY | TEMP} | UNLOGGED ] TABLE [IF NOT EXISTS]
with regards to columns that are the <i>distribution key</i> in a Greenplum table. For a
unique constraint to be enforced in Greenplum Database, the table must be hash-distributed
(not <codeph>DISTRIBUTED RANDOMLY</codeph>), and the constraint columns must be the same
- as (or a superset of) the table's distribution key columns. Also, the distribution key
- must be a left-subset of the constraint columns with the columns in the correct order. For
- example, if the primary key is (a,b,c), the distribution key can be only one of the
- following: (a), (a,b), or (a,b,c).<p>Replicated tables (<codeph>DISTRIBUTED
- REPLICATED</codeph>) can have both <codeph>PRIMARY KEY</codeph> and
- <codeph>UNIQUE</codeph>column constraints.</p><p>A primary key constraint is simply a
- combination of a unique constraint and a not-null constraint.</p><p>Greenplum Database
+ as (or a superset of) the table's distribution key columns. <p>Replicated tables
+ (<codeph>DISTRIBUTED REPLICATED</codeph>) can have both <codeph>PRIMARY KEY</codeph>
+ and <codeph>UNIQUE</codeph>column constraints.</p><p>A primary key constraint is simply
+ a combination of a unique constraint and a not-null constraint.</p><p>Greenplum Database
automatically creates a <codeph>UNIQUE</codeph> index for each <codeph>UNIQUE</codeph>
or <codeph>PRIMARY KEY</codeph> constraint to enforce uniqueness. Thus, it is not
necessary to create an index explicitly for primary key columns. <codeph>UNIQUE</codeph>
