[DOCS] Impala is not optimized for the IN operator when accessing HBASE
Change-Id: I37337a18c7add3c64795b3b2e49670493a9a8e44
Reviewed-on: http://gerrit.cloudera.org:8080/14891
Reviewed-by: Lars Volker <lv@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
diff --git a/docs/topics/impala_hbase.xml b/docs/topics/impala_hbase.xml
index 63f14af..aaf451c 100644
--- a/docs/topics/impala_hbase.xml
+++ b/docs/topics/impala_hbase.xml
@@ -110,12 +110,12 @@
the new table.)
</li>
- <li>
- You issue queries against the Impala tables. For efficient queries, use <codeph>WHERE</codeph> clauses to
- find a single key value or a range of key values wherever practical, by testing the Impala column
- corresponding to the HBase row key. Avoid queries that do full-table scans, which are efficient for
- regular Impala tables but inefficient in HBase.
- </li>
+ <li> You issue queries against the Impala tables. For efficient queries,
+ use the <codeph>WHERE</codeph> clause to find a single key value or a
+ range of key values wherever practical, by testing the Impala column
+ corresponding to the HBase row key. Avoid queries that do full-table
+ scans, which are efficient for regular Impala tables but inefficient
+ in HBase. </li>
</ul>
<p>
@@ -180,15 +180,16 @@
key or value fields. All the type enforcement is done on the Impala side.
</p>
- <p>
- For best performance of Impala queries against HBase tables, most queries will perform comparisons in the
- <codeph>WHERE</codeph> against the column that corresponds to the HBase row key. When creating the table
- through the Hive shell, use the <codeph>STRING</codeph> data type for the column that corresponds to the
- HBase row key. Impala can translate conditional tests (through operators such as <codeph>=</codeph>,
- <codeph><</codeph>, <codeph>BETWEEN</codeph>, and <codeph>IN</codeph>) against this column into fast
- lookups in HBase, but this optimization (<q>predicate pushdown</q>) only works when that column is
- defined as <codeph>STRING</codeph>.
- </p>
+ <p> For best performance of Impala queries against HBase tables, most
+ queries will perform comparisons in the <codeph>WHERE</codeph> clause
+ against the column that corresponds to the HBase row key. When creating
+ the table through the Hive shell, use the <codeph>STRING</codeph> data
+ type for the column that corresponds to the HBase row key. Impala can
+ translate predicates (through operators such as <codeph>=</codeph>,
+ <codeph><</codeph>, and <codeph>BETWEEN</codeph>) against this
+ column into fast lookups in HBase, but this optimization (<q>predicate
+ pushdown</q>) only works when that column is defined as
+ <codeph>STRING</codeph>. </p>
<p>
Starting in Impala 1.1, Impala also supports reading and writing to columns that are defined in the Hive
