Kenneth Knowles created BEAM-4700:
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Summary: JDBC driver cannot support TIMESTAMP data type
Key: BEAM-4700
URL: https://issues.apache.org/jira/browse/BEAM-4700
Project: Beam
Issue Type: New Feature
Components: dsl-sql
Reporter: Kenneth Knowles
Assignee: Kenneth Knowles
Avatica allows column representation to be customized, so a timestamp can be
stored as a variety of types. Joda ReadableInstant is none of these types:
https://github.com/apache/calcite-avatica/blob/acb675de97b9b0743c09368820a770e2ceda05f8/core/src/main/java/org/apache/calcite/avatica/util/AbstractCursor.java#L162
By default, it seems to be configured to store {{TIMESTAMP}} columns as
{{long}} values. If you run the SQL shell and select a {{TIMESTAMP}} column,
you get:
{code}
ava.lang.ClassCastException: org.joda.time.Instant cannot be cast to
java.lang.Number
at
org.apache.beam.repackaged.beam_sdks_java_extensions_sql.org.apache.calcite.avatica.util.AbstractCursor$NumberAccessor.getNumber(AbstractCursor.java:726)
at
org.apache.beam.repackaged.beam_sdks_java_extensions_sql.org.apache.calcite.avatica.util.AbstractCursor$TimestampFromNumberAccessor.getString(AbstractCursor.java:1026)
at
org.apache.beam.repackaged.beam_sdks_java_extensions_sql.org.apache.calcite.avatica.AvaticaResultSet.getString(AvaticaResultSet.java:225)
at sqlline.Rows$Row.<init>(Rows.java:183)
{code}
So, essentially, Beam SQL Shell does not support timestamps.
We may be able to:
- override how the accessor for our existing storage is created
- configure what the column representation is (this doesn't really help, since
none of the choices are ours)
- convert timestamps to longs in BeamEnumerableConverter; not sure how many
conversions will be required here
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