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From "Yingyi Bu (JIRA)" <>
Subject [jira] [Issue Comment Deleted] (ASTERIXDB-1606) Optimize "last value" query
Date Wed, 24 Aug 2016 17:29:21 GMT


Yingyi Bu updated ASTERIXDB-1606:
    Comment: was deleted

(was: Does any database provide (1)?

GREATEST is a function name in most database, e.g.:

> Optimize "last value" query
> ---------------------------
>                 Key: ASTERIXDB-1606
>                 URL:
>             Project: Apache AsterixDB
>          Issue Type: Bug
>            Reporter: Steven Jacobs
>            Priority: Minor
> We need to work on optimizing queries looking for a "most recent" or "greatest" value
of a given field. 
> As an example, consider an append-only dataset filled with user locations over time,
and suppose we want to know the user's last known location. Currently, we would need to do
this as an:
> order by $record.timeStamp
> limit 1
> We could improve this in two ways:
> 1) Improve usability by providing an alias syntax for users, e.g. "where greatest timeStamp"
> 2) Improve the compilation of such a job to only retrieve a single record.

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