SQL: [Docs] Add limitation for sorting on aggs #52210
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Add a sections to point out that when ordering by an aggregate certain restrictions are applied to the columns used in the `ORDER BY` clause. Only the exact same aggregate function(s) as in the `SELECT` clause and/or the exact same grouping keys must be used. Fixes: elastic#52204
matriv
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Pinging @elastic/es-search (:Search/SQL) |
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Pinging @elastic/es-docs (>docs) |
bpintea
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Feb 11, 2020
| It is possible to run the same queries without a `LIMIT` however in that case if the maximum size (*10000*) is passed, | ||
| an exception will be returned as {es-sql} is unable to track (and sort) all the results returned. | ||
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| Moreover, if there are aggregation(s) in the `ORDER BY`, they must be the exact the same exact aggregation |
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"they must be the exact the same exact aggregation"
bpintea
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Feb 11, 2020
| an exception will be returned as {es-sql} is unable to track (and sort) all the results returned. | ||
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| Moreover, if there are aggregation(s) in the `ORDER BY`, they must be the exact the same exact aggregation | ||
| expressions(s), as used in the `SELECT` clause. The same applies for the fields that are defined the `GROUP BY` clause: |
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"that are defined in the GROUP BY"
bpintea
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Feb 11, 2020
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| -------------------------------------------------- | ||
| SELECT age, MAX(salary) FROM test GROUP BY gender ORDER BY age % 10, MAX(salary); | ||
| SELECT age, MAX(salary) FROM test GROUP BY gender ORDER BY age, CAST(MAX(salary) AS FLOAT); | ||
| SELECT age % 10, MAX(salary) FROM test GROUP BY gender ORDER BY age, MAX(salary); | ||
| SELECT age, MAX(salary) / 12 AS max_salary FROM test GROUP BY ORDER BY age, MAX(salary); | ||
| -------------------------------------------------- |
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Might be useful to add one-two examples on how to change the statement, so that it works. Up to you.
bpintea
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Feb 11, 2020
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LGTM, left some minor needed corrections.
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Not 100% correct. Need to recheck the behaviour first. |
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Fixed the limitation to mention only the aggregate functions. |
bpintea
reviewed
Feb 12, 2020
| It is possible to run the same queries without a `LIMIT` however in that case if the maximum size (*10000*) is passed, | ||
| an exception will be returned as {es-sql} is unable to track (and sort) all the results returned. | ||
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| Moreover, the aggregation(s) used in the `ORDER BY`, must be only plain aggregate functions. No scalar |
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"must be only plain aggregate functions" could be rephrased to "can only be ..."
bpintea
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LGTM, only left a slight improvement optional suggestion.
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Add a section to point out that when ordering by an aggregate
only plain aggregate functions are allowed, no scalars/operators
can be used on top of them.
Fixes: #52204