Joined-table

Specifies how to join tables.

Syntax

table-reference [ join-type ] JOIN table-reference [ TABLESAMPLE(percent) ] [ ON join-predicate ]

Arguments

table-reference

A table name, optionally qualified.

join-type

One of the following:

• INNER (default). INNER JOIN is equivalent to a query that specifies its join predicate in a WHERE clause.

• LEFT [ OUTER ]
• RIGHT [ OUTER ]
• FULL [ OUTER ]
• NATURAL
• CROSS

TABLESAMPLE(percent)

Use simple random sampling to return an approximate percentage of records. The percentage value must be greater than 0 and less than 100. All rows in the total potential return set are equally eligible to be included in the sampling. Vertica performs this sampling before other filters in the query are applied. The number of records returned is not guaranteed to be exactly percent.

The TABLESAMPLE option is valid only with user-defined tables and Data Collector (DC) tables. Views and system tables are not supported.

ON join-predicate

Specifies the columns to join on. Invalid for NATURAL and CROSS joins, required for all other join types.

Alternative JOIN syntax options

Vertica supports two older join syntax conventions:

• Table joins specified by join predicate in a WHERE clause

• Table joins specified by a USING clause

For details, see Join Syntax.

Examples

The following SELECT statement qualifies its JOIN clause with the TABLESAMPLE option:

=> SELECT user_id.id, user_name.name FROM user_name TABLESAMPLE(50)
     JOIN user_id TABLESAMPLE(50) ON user_name.id = user_id.id;
  id  |  name
------+--------
  489 | Markus
 2234 | Cato
  763 | Pompey
(3 rows)