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https://issues.apache.org/jira/browse/TAJO-34?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13636367#comment-13636367
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Hyunsik Choi commented on TAJO-34:
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Hi Alexander,
Physical operators are in
tajo-core/tajo-core-backend/src/main/java/tajo/engine/planner/physical.
HashJoinExec and MergeJoinExec are in that directory too. Both operators work
in default as inner join operators.
Tajo uses ANTLR as a parser generator. The ANTLR parser rule is
tajo-core/tajo-core-backend/src/main/antlr3/tajo/engine/parser/NQL.g.
tajo.engine.parser.QueryAnalyzer analyzes an AST generated from SQL and
transforms the AST into an annotated query block object.
> Outer Join
> ----------
>
> Key: TAJO-34
> URL: https://issues.apache.org/jira/browse/TAJO-34
> Project: Tajo
> Issue Type: New Feature
> Reporter: Hyunsik Choi
> Labels: gsoc, gsoc2013, join, mentor
>
> h3. Background
> The current Tajo does not support outer join. The parser part for outer join
> was already implemented.
> h3. Proposal
> In this issue, we should improve LogicalPlanner/LogicalOptimizer to deal with
> outer joins. Then, we should adopt outer join to existing physical join
> operators like HashJoinExec and MergeJoinExec.
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