Select queries return raw Druid rows and support pagination.
{ "queryType": "select", "dataSource": "wikipedia", "dimensions":[], "metrics":[], "granularity": "all", "intervals": [ "2013-01-01/2013-01-02" ], "pagingSpec":{"pagingIdentifiers": {}, "threshold":5} }
There are several main parts to a select query:
| property | description | required? |
|---|---|---|
| queryType | This String should always be “select”; this is the first thing Druid looks at to figure out how to interpret the query | yes |
| dataSource | A String defining the data source to query, very similar to a table in a relational database | yes |
| intervals | A JSON Object representing ISO-8601 Intervals. This defines the time ranges to run the query over. | yes |
| filter | See Filters | no |
| dimensions | A String array of dimensions to select. If left empty, all dimensions are returned. | no |
| metrics | A String array of metrics to select. If left empty, all metrics are returned. | no |
| pagingSpec | A JSON object indicating offsets into different scanned segments. Query results will return a pagingIdentifiers value that can be reused in the next query for pagination. | yes |
| context | An additional JSON Object which can be used to specify certain flags. | no |
The format of the result is:
[{ "timestamp" : "2013-01-01T00:00:00.000Z", "result" : { "pagingIdentifiers" : { "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9" : 4 }, "events" : [ { "segmentId" : "wikipedia_editstream_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9", "offset" : 0, "event" : { "timestamp" : "2013-01-01T00:00:00.000Z", "robot" : "1", "namespace" : "article", "anonymous" : "0", "unpatrolled" : "0", "page" : "11._korpus_(NOVJ)", "language" : "sl", "newpage" : "0", "user" : "EmausBot", "count" : 1.0, "added" : 39.0, "delta" : 39.0, "variation" : 39.0, "deleted" : 0.0 } }, { "segmentId" : "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9", "offset" : 1, "event" : { "timestamp" : "2013-01-01T00:00:00.000Z", "robot" : "0", "namespace" : "article", "anonymous" : "0", "unpatrolled" : "0", "page" : "112_U.S._580", "language" : "en", "newpage" : "1", "user" : "MZMcBride", "count" : 1.0, "added" : 70.0, "delta" : 70.0, "variation" : 70.0, "deleted" : 0.0 } }, { "segmentId" : "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9", "offset" : 2, "event" : { "timestamp" : "2013-01-01T00:00:00.000Z", "robot" : "0", "namespace" : "article", "anonymous" : "0", "unpatrolled" : "0", "page" : "113_U.S._243", "language" : "en", "newpage" : "1", "user" : "MZMcBride", "count" : 1.0, "added" : 77.0, "delta" : 77.0, "variation" : 77.0, "deleted" : 0.0 } }, { "segmentId" : "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9", "offset" : 3, "event" : { "timestamp" : "2013-01-01T00:00:00.000Z", "robot" : "0", "namespace" : "article", "anonymous" : "0", "unpatrolled" : "0", "page" : "113_U.S._73", "language" : "en", "newpage" : "1", "user" : "MZMcBride", "count" : 1.0, "added" : 70.0, "delta" : 70.0, "variation" : 70.0, "deleted" : 0.0 } }, { "segmentId" : "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9", "offset" : 4, "event" : { "timestamp" : "2013-01-01T00:00:00.000Z", "robot" : "0", "namespace" : "article", "anonymous" : "0", "unpatrolled" : "0", "page" : "113_U.S._756", "language" : "en", "newpage" : "1", "user" : "MZMcBride", "count" : 1.0, "added" : 68.0, "delta" : 68.0, "variation" : 68.0, "deleted" : 0.0 } } ] } } ]
The threshold determines how many hits are returned, with each hit indexed by an offset.
The results above include:
"pagingIdentifiers" : { "wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9" : 4 },
This can be used with the next query's pagingSpec:
{ "queryType": "select", "dataSource": "wikipedia", "dimensions":[], "metrics":[], "granularity": "all", "intervals": [ "2013-01-01/2013-01-02" ], "pagingSpec":{"pagingIdentifiers": {"wikipedia_2012-12-29T00:00:00.000Z_2013-01-10T08:00:00.000Z_2013-01-10T08:13:47.830Z_v9" : 5}, "threshold":5} } 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 with each new query. When an empty results set is received, the very last page has been returned.