Joined-Table
Specifies how to join tables.
Syntax
table‑reference [join-type] JOIN table-reference[ TABLESAMPLE(sampling‑pct) ] [ ON join‑predicate ]
Parameters
table‑reference |
A table or another joined-table. |
join-type |
Valid Values:
|
TABLESAMPLE |
Specifies to use simple random sampling to return an approximate percentage of records. 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 the exact percentage of records defined by sampling‑pct. The |
sampling‑pct | Specifies the percentage of records to be returned as a part of sampling. The value must be greater than 0 and less than 100. |
ON join‑predicate |
An equi-join based on one or more columns in the joined tables. invalid for |
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 in Analyzing Data.
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)