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https://issues.apache.org/jira/browse/IOTDB-298?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17035005#comment-17035005
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Shao Wei commented on IOTDB-298:
--------------------------------
Hi, a last query scan just work as normal query scan. I've learned that we make
a copy for the memtable and this copy could be used for this query. So there
should be no blocking when multiple copies of memtable can be used during read
and write.
> Last time-value query
> ---------------------
>
> Key: IOTDB-298
> URL: https://issues.apache.org/jira/browse/IOTDB-298
> Project: Apache IoTDB
> Issue Type: New Feature
> Reporter: Jialin Qiao
> Assignee: Shao Wei
> Priority: Major
> Labels: pull-request-available
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> We have two aggregators:
> last_value -> return the value of the last data point
> max_time -> return the time of the last data point
> However, we do not have an aggregator that returns the last time-value pair.
> This is very antihuman in a time-series database :(:(:(
>
> I suggest adding a new last query:
>
> last s1 from root.sg1.d1, root.sg1.d2 or other similar grammar.
>
> The Result should be in the following format:
>
> Path, Time, Value
> root.sg1.d1.s1, 100, 100
> root.sg1.d2.s1, 10, 10
>
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