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https://issues.apache.org/jira/browse/CALCITE-1661?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15886420#comment-15886420
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Jesus Camacho Rodriguez edited comment on CALCITE-1661 at 2/27/17 8:04 PM:
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You are right, that is fair. Rounding might happen. Overflowing might happen
too, though I do not know if there is a deterministic behavior to handle it,
e.g., defined by the SQL standard.
When I proposed this fix, I was assuming that this is something that we will
document properly on the Hive side, so we can support DECIMAL type (similar to
what we do with the handling of NULL semantics by Druid). Are you suggesting
that we should not support DECIMAL in Druid?
We could check the precision&scale to control overflow, though user needs to be
aware of what is going on in Druid and that rounding might happen.
[~ashutoshc], what do you think? [~julianhyde], could you give your opinion
about this too?
was (Author: jcamachorodriguez):
You are right, that is fair. Rounding might happen. Overflowing might happen
too, though I do not know if there is a deterministic behavior to handle it,
e.g., defined by the SQL standard.
That is why I think we should check the precision&scale and act accordingly,
e.g., if DECIMAL with given precision&scale can be represented as double
without loss of precision, we store it in Druid and thus we can push the
aggregation; otherwise, we do not. That would work for COUNT, SUM, MIN, and MAX
aggregation functions that we currently support. In addition, it plays nicely
with the recognition of LONG vs DOUBLE aggregation function in Druid?
[~ashutoshc], what do you think? [~julianhyde], could you give your opinion
about this too? Maybe I am missing something... If you agree this is fine, I
will update the PR accordingly.
> Recognize aggregation function types as FRACTIONAL instead of DOUBLE
> --------------------------------------------------------------------
>
> Key: CALCITE-1661
> URL: https://issues.apache.org/jira/browse/CALCITE-1661
> Project: Calcite
> Issue Type: Bug
> Components: druid
> Affects Versions: 1.12.0
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Fix For: 1.12.0
>
>
> Currently, whether to use fractional or integer aggregations is based on
> following code (L699 in DruidQuery.java).
> {code}
> final boolean b = aggCall.getType().getSqlTypeName() == SqlTypeName.DOUBLE;
> {code}
> Since Hive might use other fractional types for the aggregation, we might end
> up using the wrong type of aggregation in Druid. We could extend the check as
> follows:
> {code}
> final boolean b =
> SqlTypeName.FRACTIONAL_TYPES.contains(aggCall.getType().getSqlTypeName());
> {code}
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