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https://issues.apache.org/jira/browse/CALCITE-497?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14257322#comment-14257322
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James Taylor commented on CALCITE-497:
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FWIW, in Phoenix the user declares the list of columns in a column family at
DDL time, so no IO would be required. If there are other column qualifiers
outside of this list that want to be accessed, then the user must declare them
at query time (using the syntax outlined in CALCITE-493).
> Support optional qualifier for column name references
> -----------------------------------------------------
>
> Key: CALCITE-497
> URL: https://issues.apache.org/jira/browse/CALCITE-497
> Project: Calcite
> Issue Type: Sub-task
> Reporter: James Taylor
> Assignee: Julian Hyde
> Labels: phoenix
>
> Some systems, such as HBase, have a named group to which columns belong (i.e.
> a column family in this case). To disambiguate column references (i.e. if the
> same column name is used in different column families), it's useful to allow
> an optional qualifier. This is similar to the RECORD field mechanism that
> Calcite already supports, but in this case the record name would be optional,
> since it's not necessary if the column names are unique. For example:
> http://phoenix.apache.org/language/index.html#column_ref
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