[HIVE-364] Hive Operators should calculate the value of common expressions just once

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Query Processor
• Assignee: Unassigned
• Reporter: Zheng Shao
• Created: 24/Mar/09 20:57
• Updated: 05/Apr/11 23:21

Description

Currently, if we have "t.a + t.b" in 2 different expressions in the select clause / where clause, we are computing it twice.
We should cache the value of the expression evaluation result to save CPU time.