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.

NOTE：

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:

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

The result shows below:

  1. +-----------------------------+-----------------+-----------+------+--------+
  2. |                         Time|           Device|temperature|status|hardware|
  3. +-----------------------------+-----------------+-----------+------+--------+
  4. |2017-11-01T00:00:00.000+08:00|root.ln.wf01.wt01|      25.96|  true|    null|
  5. |2017-11-01T00:01:00.000+08:00|root.ln.wf01.wt01|      24.36|  true|    null|
  6. |1970-01-01T08:00:00.001+08:00|root.ln.wf02.wt02|       null|  true|      v1|
  7. |1970-01-01T08:00:00.002+08:00|root.ln.wf02.wt02|       null| false|      v2|
  8. |2017-11-01T00:00:00.000+08:00|root.ln.wf02.wt02|       null|  true|      v2|
  9. |2017-11-01T00:01:00.000+08:00|root.ln.wf02.wt02|       null|  true|      v2|
  10. +-----------------------------+-----------------+-----------+------+--------+
  11. Total line number = 6
  12. It costs 0.012s