Author: hashutosh
Date: Tue Jul 9 08:31:37 2013
New Revision: 1501129
URL: http://svn.apache.org/r1501129
Log:
HIVE-4819 : Comments in CommonJoinOperator for aliasTag is not valid (Navis via
Ashutosh Chauhan)
Modified:
hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/CommonJoinOperator.java
Modified:
hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/CommonJoinOperator.java
URL:
http://svn.apache.org/viewvc/hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/CommonJoinOperator.java?rev=1501129&r1=1501128&r2=1501129&view=diff
==============================================================================
---
hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/CommonJoinOperator.java
(original)
+++
hive/trunk/ql/src/java/org/apache/hadoop/hive/ql/exec/CommonJoinOperator.java
Tue Jul 9 08:31:37 2013
@@ -360,26 +360,46 @@ public abstract class CommonJoinOperator
// filter tags for objects
protected transient short[] filterTags;
- // ANDed value of all filter tags in current join group
- // if any of values passes on outer join alias (which makes zero for the tag
alias),
- // it means there exists a pair for it, and no need to check outer join
(just do inner join)
- //
- // for example, with table a, b something like,
- // a, b = 100, 10 | 100, 20 | 100, 30
- //
- // the query "a FOJ b ON a.k=b.k AND a.v>0 AND b.v>20" makes values with tag
- //
- // a = 100, 10, 00000010 | 100, 20, 00000010 | 100, 30, 00000010 : 0/1 for
'b' (alias 1)
- // b = 100, 10, 00000001 | 100, 20, 00000001 | 100, 30, 00000000 : 0/1 for
'a' (alias 0)
- //
- // which makes aliasFilterTags for a = 00000010, for b = 00000000
- //
- // for LO, b = 0000000(0) means there is a pair object(s) in 'b' (has no
'a'-null case)
- // for RO, a = 000000(1)0 means there is no pair object in 'a' (has null-'b'
case)
- //
- // result : 100, 10 + 100, 30 | 100, 20 + 100, 30 | 100, 30 + 100, 30 |
- // N + 100, 10 | N + 100, 20
- //
+ /**
+ * On filterTags
+ *
+ * ANDed value of all filter tags in current join group
+ * if any of values passes on outer join alias (which makes zero for the tag
alias),
+ * it means there exists a pair for it and safely regarded as a inner join
+ *
+ * for example, with table a, b something like,
+ * a = 100, 10 | 100, 20 | 100, 30
+ * b = 100, 10 | 100, 20 | 100, 30
+ *
+ * the query "a FO b ON a.k=b.k AND a.v>10 AND b.v>30" makes filter map
+ * 0(a) = [1(b),1] : a.v>10
+ * 1(b) = [0(a),1] : b.v>30
+ *
+ * for filtered rows in a (100,10) create a-NULL
+ * for filtered rows in b (100,10) (100,20) (100,30) create NULL-b
+ *
+ * with 0(a) = [1(b),1] : a.v>10
+ * 100, 10 = 00000010 (filtered)
+ * 100, 20 = 00000000 (valid)
+ * 100, 30 = 00000000 (valid)
+ * -------------------------
+ * sum = 00000000 : for valid rows in b, there is at least one pair in
a
+ *
+ * with 1(b) = [0(a),1] : b.v>30
+ * 100, 10 = 00000001 (filtered)
+ * 100, 20 = 00000001 (filtered)
+ * 100, 30 = 00000001 (filtered)
+ * -------------------------
+ * sum = 00000001 : for valid rows in a (100,20) (100,30), there is no
pair in b
+ *
+ * result :
+ * 100, 10 : N, N
+ * N, N : 100, 10
+ * N, N : 100, 20
+ * N, N : 100, 30
+ * 100, 20 : N, N
+ * 100, 30 : N, N
+ */
protected transient short[] aliasFilterTags;
// all evaluation should be processed here for valid aliasFilterTags
