Oliver Lee created CALCITE-5982:
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Summary: Allow overloading the created enumerable in Calcite when
calling getTables() or getColumns()
Key: CALCITE-5982
URL: https://issues.apache.org/jira/browse/CALCITE-5982
Project: Calcite
Issue Type: New Feature
Reporter: Oliver Lee
Assignee: Oliver Lee
The goal is to introduce a mechanism that allows overloading the enumerable
type that is created when {{getTables()}} and {{getColumns()}} is called. If a
user provides an overloaded {{{}MetaTable{}}}/ {{MetaColumn}} class, then they
can add in additional metadata fields that they would like to be transferred.
Currently, {{CalciteMetaImpl}} in {{getTables()}} and {{getColumns()}} calls
are hardcoded to do reflection on {{MetaTable.class}} and {{MetaColumn.class}}
‘ fields, matched with the list of column names that are passed in. Reflection
is important here, as it creates the proper {{ColumnMetaData}} and
{{Signature}} that the client needs to deserialize.
See here for {{[getTables()|#L270]]}} and here for
[{{getColumns()}}|https://github.com/apache/calcite/blob/164ff0a27e243850d294908dc5cff90760d0a35a/core/src/main/java/org/apache/calcite/jdbc/CalciteMetaImpl.java#L320]
I would like to introduce fields ( {{metaTableClass}} , {{metaColumnClass}} )
on {{CalciteMetaImpl}} that determine which class to use for each of these.
This will be configured as a {{CalciteConnectionProperty}} when making the
{{jdbc:calcite}} connection
Requirements:
* User can specify in {{Properties}} new {{CalciteConnectionProperty}} ’s to
specify which overloaded class of {{CalciteMetaTable}} and {{MetaColumn}} to use
* If not specified, it will default to {{CalciteMetaTable.class}} and
{{MetaColumn.class}}
The provided overloaded class will create a subclass of {{CalciteMetaTable}} /
{{MetaColumn}} that has the same shape constructor and also provide an override
for the function {{{}getColumnNames(){}}}.
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