KUDU-2671: Update upstream docs

This patch updates the upstream docs to include range specific
hash schemas within the partitioning section. An example
with the proper sql syntax is also included in the kudu impala
integration doc.

Change-Id: I8da554851a124d1d357be65d8bcc2c6c37875dcc
Reviewed-on: http://gerrit.cloudera.org:8080/21108
Tested-by: Kudu Jenkins
Reviewed-by: Alexey Serbin <[email protected]>

docs/kudu_impala_integration.adoc

@@ -485,6 +485,48 @@ The example creates 16 partitions. You could also use `HASH (id, sku) PARTITIONS
 However, a scan for `sku` values would almost always impact all 16 partitions, rather
 than possibly being limited to 4.
 
+.Range-Specific Hash Schemas
+As of 1.17, Kudu supports range-specific hash schemas for tables. It's possible to
+add ranges with a hash schema independent of the table-wide hash schema. This can be
+done while creating or altering the table. The number of hash partition levels must
+be the same across all ranges in a table.
+
+[source, sql]
+----
+CREATE TABLE cust_behavior (
+  id BIGINT,
+  sku STRING,
+  salary STRING,
+  edu_level INT,
+  usergender STRING,
+  `group` STRING,
+  city STRING,
+  postcode STRING,
+  last_purchase_price FLOAT,
+  last_purchase_date BIGINT,
+  category STRING,
+  rating INT,
+  fulfilled_date BIGINT,
+  PRIMARY KEY (id, sku)
+)
+PARTITION BY HASH (id) PARTITIONS 4
+RANGE (sku)
+(
+  PARTITION VALUES < 'g'
+  PARTITION 'g' <= VALUES < 'o'
+      HASH (id) PARTITIONS 6
+  PARTITION 'o' <= VALUES < 'u'
+      HASH (id) PARTITIONS 8
+  PARTITION 'u' <= VALUES
+)
+STORED AS KUDU;
+----
+
+This example uses the range-specific hash schema feature for the middle two
+ranges. The table-wide hash schema has 4 buckets while the hash schemas
+for the middle two ranges have 6 and 8 buckets respectively. This can be done
+in cases where we expect a higher workload in such ranges.
+
 .Non-Covering Range Partitions
 Kudu 1.0 and higher supports the use of non-covering range partitions,
 which address scenarios like the following:

docs/schema_design.adoc

@@ -435,6 +435,22 @@ NOTE: see the <<hash-range-partitioning-example>> and the
 <<hash-hash-partitioning-example>> for further discussion of multilevel
 partitioning.
 
+[[flexible-partitioning]]
+=== Flexible Partitioning
+
+As of 1.17, Kudu supports range-specific hash schema for tables. It's now
+possible to add ranges with their own unique hash schema independent of the
+table-wide hash schema. This can be done while creating or altering the table.
+This feature helps mitigate potential hotspotting as more buckets can be
+added for a hash schema of a range that expects more workload.
+
+[[same-number-of-hash-levels]]
+[IMPORTANT]
+.Same Number of Hash Levels
+The number of hash partition levels must be the same across for all the ranges
+in a table. See <<multilevel-partitioning>> for more details on hash partition
+levels.
+
 [[partition-pruning]]
 === Partition Pruning