[CALCITE-1429] Druid adapter must send "fromNext" when requesting rows from Druid

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.11.0
• Component/s: druid-adapter
• Assignee: Julian Hyde
• Reporter: Jiarong Wei
• Created: 11/Oct/16 14:38
• Updated: 06/Jan/17 19:30
• Resolved: 19/Oct/16 04:27

Description

Druid adapter gets an error while fetching data. As mentioned in Druid documentation,

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.

I think Druid adapter presumes this feature is turned on but it's not set in code.

Also, previousOffset may not be reasonable, see DruidQuery. 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.