Query Alignment Mode
Less than 1 minute
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 byTime
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
It costs 0.012s