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Improve documentation of COLLECT AQL statement.

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Max Neunhoeffer 2014-11-28 13:25:56 +01:00 committed by Frank Celler
parent 5e3a41dabf
commit 0c12f5a3d9
1 changed files with 12 additions and 1 deletions
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13
Documentation/Books/Users/Aql/Operations.mdpp
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@ -228,7 +228,18 @@ contains the group value.
The second form does the same as the first form, but additionally introduces a
variable (specified by *groups*) that contains all elements that fell into the
group. Specifying the *INTO* clause is optional-
group. This works as follows: The *groups* variable is a list containing
as many elements as there are in the group. Each member of that list is
a JSON object in which the value of every variable that is defined in the
AQL query is bound to the corresponding attribute. Note that this considers
all variables that are defined before the *COLLECT* statement, but not those on
the top level (outside of any *FOR*), unless the *COLLECT* statement is itself
on the top level, in which case all variables are taken. Furthermore note
that it is possible that the optimizer moves *LET* statements out of *FOR*
statements to improve performance. In a future version of ArangoDB we plan
to allow to configure exactly the values of which variables are copied
into the *groups* variable, since excessive copying can have a negative
impact on performance. Specifying the *INTO* clause is optional.
```
FOR u IN users