Jiarong Wei created CALCITE-1429:
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Summary: Error of deciding pagingIdentifiers in select query for
Druid
Key: CALCITE-1429
URL: https://issues.apache.org/jira/browse/CALCITE-1429
Project: Calcite
Issue Type: Bug
Components: druid
Reporter: Jiarong Wei
Assignee: Julian Hyde
As mentioned in [Druid
documentation|http://druid.io/docs/0.9.1.1/querying/select-query.html],
{quote}
Note that in the second query, an offset is specified and that it is 1 greater
than the largest offset found in the initial results. To return the next
"page", this offset must be incremented by 1 (should be decremented by 1 for
descending query), with each new query, but with option {{fromNext}} enabled,
this operation is not needed. When an empty results set is received, the very
last page has been returned.
{quote}
I think Druid adapter
[presumes|https://github.com/apache/calcite/blob/master/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java#L935]
this feature is turned on but it's not set in
[code|https://github.com/apache/calcite/blob/master/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java#L627].
Also, {{previousOffset}} may not be reasonable, see
[DruidQuery|https://github.com/apache/calcite/blob/master/druid/src/main/java/org/apache/calcite/adapter/druid/DruidQuery.java#L940].
I think whether we have already fetched all data is decided by the next
request. If we don't have any data returned on next request, that means
fetching is done.
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