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https://issues.apache.org/jira/browse/DRILL-8261?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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James Turton updated DRILL-8261:
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Description: The attributes MAP column generated by the XML format plugin
is currently explicit and present in wildcard selects. However, attributes are
frequently not present at all in XML data, or are better queried using explicit
projections of the individual attributes of interest to scalars. The motivating
example here is an ETL-style query that transforms XML to Parquet using a CTAS
with a wildcard column spec. This query will fail for XML that has no
attributes because the Parquet writer cannot write a Parquet schema containing
the empty struct produced by the attributes map. It is therefore proposed that
the attributes MAP becomes an implicit column. (was: The attributes MAP column
generated by the XML format plugin is currently explicit and present in
wildcard selects. However, attributes are frequently not present at all in XML
data, or are better queried using explicit projections of the individual
attributes of interest to scalars. The motivating example here is an ETL-style
query that transforms XML to Parquet using a CTAS with a wildcard column spec.
This query will fail for XML that has no attributes because the Parquet writer
cannot write a Parquet schema containing an empty struct. It is therefore
proposed that the attributes MAP becomes an implicit column.)
> Make the XML format plugin's attributes MAP an implicit column
> --------------------------------------------------------------
>
> Key: DRILL-8261
> URL: https://issues.apache.org/jira/browse/DRILL-8261
> Project: Apache Drill
> Issue Type: Improvement
> Components: Storage - XML
> Affects Versions: 1.20.1
> Reporter: James Turton
> Assignee: James Turton
> Priority: Minor
> Fix For: 2.0.0
>
>
> The attributes MAP column generated by the XML format plugin is currently
> explicit and present in wildcard selects. However, attributes are frequently
> not present at all in XML data, or are better queried using explicit
> projections of the individual attributes of interest to scalars. The
> motivating example here is an ETL-style query that transforms XML to Parquet
> using a CTAS with a wildcard column spec. This query will fail for XML that
> has no attributes because the Parquet writer cannot write a Parquet schema
> containing the empty struct produced by the attributes map. It is therefore
> proposed that the attributes MAP becomes an implicit column.
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