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commit 345d012fff81b0d2c261ab15ec29b9e1ead66192 Author: Alex Rodoni <[email protected]> AuthorDate: Thu Feb 14 12:43:02 2019 -0800 IMPALA-8195: [DOCS] Impala supports Cartesian joins - Removed the note that Impala does not support Cartesian joins. Change-Id: I8734a4c2cb63b1a3229660e01d45a578a42efc29 Reviewed-on: http://gerrit.cloudera.org:8080/12487 Tested-by: Impala Public Jenkins <[email protected]> Reviewed-by: Tim Armstrong <[email protected]> --- docs/topics/impala_joins.xml | 31 +++++-------------------------- 1 file changed, 5 insertions(+), 26 deletions(-) diff --git a/docs/topics/impala_joins.xml b/docs/topics/impala_joins.xml index ef0a67a..2c8cc94 100644 --- a/docs/topics/impala_joins.xml +++ b/docs/topics/impala_joins.xml @@ -34,13 +34,11 @@ under the License. <conbody> - <p> - <indexterm audience="hidden">joins</indexterm> - A join query is a <codeph>SELECT</codeph> statement that combines data from two or more tables, - and returns a result set containing items from some or all of those tables. It is a way to - cross-reference and correlate related data that is organized into multiple tables, typically - using identifiers that are repeated in each of the joined tables. - </p> + <p> A join query is a <codeph>SELECT</codeph> statement that combines data + from two or more tables, and returns a result set containing items from + some or all of those tables. It is a way to cross-reference and correlate + related data that is organized into multiple tables, typically using + identifiers that are repeated in each of the joined tables. </p> <p conref="../shared/impala_common.xml#common/syntax_blurb"/> @@ -121,25 +119,6 @@ SELECT t1.c1, t2.c2 FROM <b>t1 JOIN t2</b> SELECT lhs.id, rhs.parent, lhs.c1, rhs.c2 FROM tree_data lhs, tree_data rhs WHERE lhs.id = rhs.parent;</codeblock> <p> - <b>Cartesian joins:</b> - </p> - - <p> - To avoid producing huge result sets by mistake, Impala does not allow Cartesian joins of the form: -<codeblock>SELECT ... FROM t1 JOIN t2; -SELECT ... FROM t1, t2;</codeblock> - If you intend to join the tables based on common values, add <codeph>ON</codeph> or <codeph>WHERE</codeph> - clauses to compare columns across the tables. If you truly intend to do a Cartesian join, use the - <codeph>CROSS JOIN</codeph> keyword as the join operator. The <codeph>CROSS JOIN</codeph> form does not use - any <codeph>ON</codeph> clause, because it produces a result set with all combinations of rows from the - left-hand and right-hand tables. The result set can still be filtered by subsequent <codeph>WHERE</codeph> - clauses. For example: - </p> - -<codeblock>SELECT ... FROM t1 CROSS JOIN t2; -SELECT ... FROM t1 CROSS JOIN t2 WHERE <varname>tests_on_non_join_columns</varname>;</codeblock> - - <p> <b>Inner and outer joins:</b> </p>
