Details
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Task
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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None
Description
SQL standard supports EXCLUDE clause within window frame definition.
We currently have it in sql_yacc.yy. The statement is parsed, but ignored:
opt_window_frame_clause:
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/* empty */ {}
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| window_frame_units window_frame_extent opt_window_frame_exclusion
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opt_window_frame_exclusion:
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/* empty */ { $$= Window_frame::EXCL_NONE; }
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| EXCLUDE_SYM CURRENT_SYM ROW_SYM
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{ $$= Window_frame::EXCL_CURRENT_ROW; }
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| EXCLUDE_SYM GROUP_SYM
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{ $$= Window_frame::EXCL_GROUP; }
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| EXCLUDE_SYM TIES_SYM
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{ $$= Window_frame::EXCL_TIES; }
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| EXCLUDE_SYM NO_SYM OTHERS_SYM
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{ $$= Window_frame::EXCL_NONE; }
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;
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The question is - should we implement frame exclusion? It doesn't seem to be supported by anybody:
- PostgreSQL: http://www.postgresql.org/docs/9.5/static/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS
- Oracle: http://docs.oracle.com/cd/E11882_01/server.112/e41084/functions004.htm#SQLRF06174
- MS SQL server: https://msdn.microsoft.com/en-us/library/ms189461.aspx
- Apache Drill: https://drill.apache.org/docs/sql-window-functions-introduction/
- Amazon Redshift: http://docs.aws.amazon.com/redshift/latest/dg/r_Window_function_synopsis.html
If we decide not to support Frame Exclusion, we should disable it in the parser so that it doesn't confuse anybody.
Attachments
Issue Links
- is part of
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- Closed
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Made a decision on the optimizer call: we will not support frame exclusion (at least for the first version).
The parts of the grammar should remain, but attempt to specify any exclusion clause will cause a "Not supported" or a "not implemented" error (check what error code/message we have)