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Query Alignment Mode

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Query Alignment Mode

In addition, IoTDB supports another result set format: ALIGN BY DEVICE.

align by device

The ALIGN BY DEVICE indicates that the deviceId is considered as a column. Therefore, there are totally limited columns in the dataset.


1.You can see the result of 'align by device' as one relational table, Time + Device is the primary key of this Table.

2.The result is order by Device firstly, and then by Time order.

The SQL statement is:

select * from root.ln.** where time <= 2017-11-01T00:01:00 align by device;

The result shows below:

|                         Time|           Device|temperature|status|hardware|
|2017-11-01T00:00:00.000+08:00|root.ln.wf01.wt01|      25.96|  true|    null|
|2017-11-01T00:01:00.000+08:00|root.ln.wf01.wt01|      24.36|  true|    null|
|1970-01-01T08:00:00.001+08:00|root.ln.wf02.wt02|       null|  true|      v1|
|1970-01-01T08:00:00.002+08:00|root.ln.wf02.wt02|       null| false|      v2|
|2017-11-01T00:00:00.000+08:00|root.ln.wf02.wt02|       null|  true|      v2|
|2017-11-01T00:01:00.000+08:00|root.ln.wf02.wt02|       null|  true|      v2|
Total line number = 6
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