[TAJO-1092] Improve the function system to allow other function implementation types

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.10.0, block_iteration
• Component/s: Function/UDF
• Assignee: Hyunsik Choi
• Reporter: Hyunsik Choi
• Created: 02/Oct/14 07:10
• Updated: 15/Oct/14 17:59
• Resolved: 15/Oct/14 17:42

Description

In the current function system, each function implementation is a single Java class subclassed from org.apache.tajo.catalog.function.Function.

In this approach, there are many rooms for improvement. This approach always uses Datum as input and output values of functions, creating unnecessary objects. It does not likely to exploit given information included query statements; for example, some parameters are constants or variables.

In this issue, I propose the improvement to allow the function system to support other function implementation types. In addition, I propose three function implementation types:

• legacy Java class function provided by the current Tajo
• static method in Java class
• code generation by ASM

Later, we could expand this feature to allow Pig or Hive functions in Tajo.

Issue Links

• is depended upon by: TAJO-1057 Function and UDF mechanism should not use Datum as parameter and return values
• is depended upon by: TAJO-1058 Implement off-heap hash table for hash aggregation