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https://issues.apache.org/jira/browse/CALCITE-501?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14230145#comment-14230145
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Julian Hyde commented on CALCITE-501:
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Yes, I always wanted to do this. The idea is that there should be rules that
know about the various access paths into a collection (full scan, range scan of
a sorted collection, indexed access via a map) and those translate into
alternative RelNodes. Each rule should be driven by metadata (e.g. annotations).
I think the idea of a sorted table will also be important. Note that
ArrayTable.Content.sortField is not used at present - we should use it. And we
could extend the Table interface to declare the table's sort order. I don't
know whether rules will explicitly look for sorted tables or whether they would
create them anyway and discover that range- or point-scans are costed much
cheaper.
> Implement indexed access paths in ReflectiveSchema
> --------------------------------------------------
>
> Key: CALCITE-501
> URL: https://issues.apache.org/jira/browse/CALCITE-501
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.0.0-incubating
> Reporter: Vladimir Sitnikov
> Assignee: Julian Hyde
>
> {{ReflectiveSchema}} is not able to perform indexed scan of a particular
> collection.
> It would be nice if it could find rows by a given key.
> This would demonstrate the way to implement indexed access path in Calcite:
> rules, filter matching.
> The sketch API can be as follows:
> {code:java}
> public static class CatchallSchema {
> public final Employee[] employees = {
> new Employee(1, 10, "A", 0f, null),
> new Employee(2, 10, "Ab", 0f, null),
> new Employee(3, 10, "Abc", 0f, null),
> new Employee(4, 10, "Abd", 0f, null),
> };
> // Return the data
> public Employee[] findEmployeesByName(String name);
> // or
> // List of indices into "employees" collection
> public int[] findEmployeesByName(String name);
> }
> {code}
> Alternative solution is to treat {{Map/SortedMap}} somehow in a special way.
> {code:java}
> // When Filter(name=?, Scan) can be transformed to MapGet(name=?)
> public Map<String, Employee> employees;
> {code}
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