mirror of https://github.com/apache/druid.git
56 lines
1.8 KiB
Markdown
56 lines
1.8 KiB
Markdown
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Segment metadata queries return per segment information about:
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\* Cardinality of all columns in the segment
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\* Estimated byte size for the segment columns in TSV format
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\* Interval the segment covers
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\* Column type of all the columns in the segment
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\* Estimated total segment byte size in TSV format
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\* Segment id
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<code>{
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"queryType":"segmentMetadata",
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"dataSource":"sample_datasource",
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"intervals":["2013-01-01/2014-01-01"],
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}
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</code>
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There are several main parts to a segment metadata query:
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|property|description|required?|
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|--------|-----------|---------|
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|queryType|This String should always be “segmentMetadata”; this is the first thing Druid looks at to figure out how to interpret the query|yes|
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|dataSource|A String defining the data source to query, very similar to a table in a relational database|yes|
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|intervals|A JSON Object representing ISO-8601 Intervals. This defines the time ranges to run the query over.|yes|
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|merge|Merge all individual segment metadata results into a single result|no|
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|context|An additional JSON Object which can be used to specify certain flags.|no|
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The format of the result is:
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<code>[ {
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"id" : "some_id",
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"intervals" : [ "2013-05-13T00:00:00.000Z/2013-05-14T00:00:00.000Z" ],
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"columns" : {
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"__time" : {
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"type" : "LONG",
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"size" : 407240380,
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"cardinality" : null
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},
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"dim1" : {
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"type" : "STRING",
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"size" : 100000,
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"cardinality" : 1944
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},
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"dim2" : {
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"type" : "STRING",
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"size" : 100000,
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"cardinality" : 1504
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},
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"metric1" : {
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"type" : "FLOAT",
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"size" : 100000,
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"cardinality" : null
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}
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},
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"size" : 300000
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} ]
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</code>
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