[jira] [Resolved] (CALCITE-1276) In Druid adapter, deduce columns by running a "segmentMetadata" query

["Julian Hyde (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CALCITE-1276?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Julian Hyde resolved CALCITE-1276.
----------------------------------
       Resolution: Fixed
    Fix Version/s: 1.8.0

Fixed in http://git-wip-us.apache.org/repos/asf/calcite/commit/435e2030. Documentation has not yet been updated, but I will do it before 1.8 is announced.

> In Druid adapter, deduce columns by running a "segmentMetadata" query
> ---------------------------------------------------------------------
>
>                 Key: CALCITE-1276
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1276
>             Project: Calcite
>          Issue Type: Bug
>          Components: druid
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>             Fix For: 1.8.0
>
>
> In Druid adapter, deduce columns by running a "segmentMetadata" query. Currently a Druid model must contain "dimensions" and "metrics" fields. If either of these are absent, Calcite should run a [segment metadata query|http://druid.io/docs/latest/querying/segmentmetadataquery.html] and take the resulting "columns" and "aggregators" fields and make them into columns.
> The effect will be that the Druid adapter will be easier to configure. You will be able to connect without a model, per CALCITE-1259:
> {code}
> jdbc:calcite:schema=wiki; schemaFactory= org.apache.calcite.adapter.druid.DruidSchemaFactory; schema.url=http://localhost:8082/druid/v2/?pretty
> {code}
> It will also adapt to schema changes. If there are multiple segments, and the schema evolves over time, I suppose that the segments might have different columns and aggregators. Calcite should use {{"merge": true, "lenientAggregatorMerge": false}} to combine them.



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