Pagination with Offset in Druid

[Pravesh Gupta]

Hi,

Is Pagination with start Offset supported in Druid.

Given my Page Size is 100, If I go from Page 1 to Page 2, is there any way I can get results from 100 till 200 ?

Currently I am using "threshold" field and for above use case getting  2 * 100 = 200 rows , which i feel is not good from improvement point of view.

Is there anything like start_offset ?

I hope I am able to make my self clear here.

Thanks,

Pravesh Gupta

[Ankush Kapur]

Hi Pravesh,

Assuming you are asking about paging with a Select query.

The key to paging in a select query is to use pagingSpec object with the appropriate paging identifiers, as mentioned here, http://druid.io/docs/latest/querying/select-query.html

When you request the first page, there will be no pagingIdentifiers,

"pagingSpec":{"pagingIdentifiers": {}, "threshold":100}

The response object for this query will have pagingIndentifiers that you need to use for the subsequent page.

    "pagingIdentifiers" : {
      "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9" : 4
    },

So for the next page (page 2), you need to increment the segment offsets and include them in your request.

"pagingSpec":{"pagingIdentifiers": {"wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9" : 100}, "threshold":5}

If you want druid to perform the increment/decrement itself then include "fromNext": true in your property.(refer to the select query documentation)

Keep in mind, you need to include segments offsets from all previous requests for subsequent pages.

Hope this help

Ankush

[Pravesh Gupta]

Thanks Ankush for the details.

I was actually asking for TopN Query type.
Is there any way to do what u described with TopN query , or Select Query is the only option.

Thanks,
Pravesh Gupta

[Slim Bouguerra]

No

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B-Slim
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