54 lines
1.6 KiB
Plaintext
54 lines
1.6 KiB
Plaintext
[discrete]
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[[esql-stats-by]]
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=== `STATS ... BY`
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Use `STATS ... BY` to group rows according to a common value and calculate one
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or more aggregated values over the grouped rows.
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[source.merge.styled,esql]
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----
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include::{esql-specs}/docs.csv-spec[tag=stats]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/docs.csv-spec[tag=stats-result]
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|===
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If `BY` is omitted, the output table contains exactly one row with the
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aggregations applied over the entire dataset:
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[source.merge.styled,esql]
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----
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include::{esql-specs}/docs.csv-spec[tag=statsWithoutBy]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/docs.csv-spec[tag=statsWithoutBy-result]
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|===
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It's possible to calculate multiple values:
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[source,esql]
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----
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include::{esql-specs}/docs.csv-spec[tag=statsCalcMultipleValues]
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----
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It's also possible to group by multiple values (only supported for long and
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keyword family fields):
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[source,esql]
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----
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include::{esql-specs}/docs.csv-spec[tag=statsGroupByMultipleValues]
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----
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The following aggregation functions are supported:
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include::../functions/aggregation-functions.asciidoc[tag=agg_list]
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NOTE: `STATS` without any groups is much much faster than adding group.
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NOTE: Grouping on a single field is currently much more optimized than grouping
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on many fields. In some tests we've seen grouping on a single `keyword`
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field to be five times faster than grouping on two `keyword` fields. Don't
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try to work around this combining the two fields together with something
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like <<esql-concat>> and then grouping - that's not going to be faster.
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