Hyunsik Choi created TAJO-906:
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Summary: Runtime code generation for evaluating expression trees
Key: TAJO-906
URL: https://issues.apache.org/jira/browse/TAJO-906
Project: Tajo
Issue Type: Sub-task
Components: physical operator
Reporter: Hyunsik Choi
Assignee: Hyunsik Choi
Fix For: 0.9.0
We have used EvalNode for two purposes:
* logical planning of expressions
* evaluation of expressions
EvalNode still is very nice for the purpose of logical planning. But, each
EvalNode tree takes Datum included in a tuple and results in a Datum as a
evaluation result.
So, the current approach requires many object creations, and causes interpret
overheads, meaning that each one evaluation involves tree traverses and many
function calls. interpretation involves also many branches, and it is harmful
to CPU pipelining.
I propose Java byte code generation for each expression, and I'll use ASM
(http://asm.ow2.org/) for it. This approach will write native java byte code,
eliminating many condition branches and function calls. In addition, it is
easier to deal with java primitive data types for expressions.
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