Machbase DBMS
Feature and Tables
Tag Table
Manipulating tag data
Delete tag data

Delete tag data

Tag data deletion constraints

Machbase only supports deletion of data before a specific time.

Unsupported tag data deletion condition

  • Delete specific tag ID data
  • Delete data for a specific time range
  • Delete specific time range data for a specific tag

Supported tag data deletion condition

  • Delete all tags before a specific time
  • Delete all data

Delete all tags before a specific time

If you specify the time of the BEFORE statement, all tags before that time are deleted.

DELETE FROM TAG BEFORE TO_DATE('Time-string');
## Original Data
Mach> select * from tag;
NAME TIME VALUE
--------------------------------------------------------------------------------------
TAG_0001 2018-01-01 01:00:00 000:000:000 1
TAG_0001 2018-01-02 02:00:00 000:000:000 2
TAG_0001 2018-01-03 03:00:00 000:000:000 3
TAG_0001 2018-01-04 04:00:00 000:000:000 4
TAG_0001 2018-01-05 05:00:00 000:000:000 5
TAG_0001 2018-01-06 06:00:00 000:000:000 6
TAG_0001 2018-01-07 07:00:00 000:000:000 7
TAG_0001 2018-01-08 08:00:00 000:000:000 8
TAG_0001 2018-01-09 09:00:00 000:000:000 9
TAG_0001 2018-01-10 10:00:00 000:000:000 10
TAG_0002 2018-02-01 01:00:00 000:000:000 11
TAG_0002 2018-02-02 02:00:00 000:000:000 12
TAG_0002 2018-02-03 03:00:00 000:000:000 13
TAG_0002 2018-02-04 04:00:00 000:000:000 14
TAG_0002 2018-02-05 05:00:00 000:000:000 15
TAG_0002 2018-02-06 06:00:00 000:000:000 16
TAG_0002 2018-02-07 07:00:00 000:000:000 17
TAG_0002 2018-02-08 08:00:00 000:000:000 18
TAG_0002 2018-02-09 09:00:00 000:000:000 19
TAG_0002 2018-02-10 10:00:00 000:000:000 20
[20] row(s) selected.
 
Mach> delete from tag before to_date('2018-02-01');
10 row(s) deleted.
 
Mach> select * from tag;
NAME TIME VALUE
--------------------------------------------------------------------------------------
TAG_0002 2018-02-01 01:00:00 000:000:000 11
TAG_0002 2018-02-02 02:00:00 000:000:000 12
TAG_0002 2018-02-03 03:00:00 000:000:000 13
TAG_0002 2018-02-04 04:00:00 000:000:000 14
TAG_0002 2018-02-05 05:00:00 000:000:000 15
TAG_0002 2018-02-06 06:00:00 000:000:000 16
TAG_0002 2018-02-07 07:00:00 000:000:000 17
TAG_0002 2018-02-08 08:00:00 000:000:000 18
TAG_0002 2018-02-09 09:00:00 000:000:000 19
TAG_0002 2018-02-10 10:00:00 000:000:000 20
[10] row(s) selected.

Delete all data

If there are no conditions, all data is deleted.

## Original Data
Mach> select * from tag;
NAME TIME VALUE
--------------------------------------------------------------------------------------
TAG_0001 2018-01-01 01:00:00 000:000:000 1
TAG_0001 2018-01-02 02:00:00 000:000:000 2
TAG_0001 2018-01-03 03:00:00 000:000:000 3
TAG_0001 2018-01-04 04:00:00 000:000:000 4
TAG_0001 2018-01-05 05:00:00 000:000:000 5
TAG_0001 2018-01-06 06:00:00 000:000:000 6
TAG_0001 2018-01-07 07:00:00 000:000:000 7
TAG_0001 2018-01-08 08:00:00 000:000:000 8
TAG_0001 2018-01-09 09:00:00 000:000:000 9
TAG_0001 2018-01-10 10:00:00 000:000:000 10
TAG_0002 2018-02-01 01:00:00 000:000:000 11
TAG_0002 2018-02-02 02:00:00 000:000:000 12
TAG_0002 2018-02-03 03:00:00 000:000:000 13
TAG_0002 2018-02-04 04:00:00 000:000:000 14
TAG_0002 2018-02-05 05:00:00 000:000:000 15
TAG_0002 2018-02-06 06:00:00 000:000:000 16
TAG_0002 2018-02-07 07:00:00 000:000:000 17
TAG_0002 2018-02-08 08:00:00 000:000:000 18
TAG_0002 2018-02-09 09:00:00 000:000:000 19
TAG_0002 2018-02-10 10:00:00 000:000:000 20
[20] row(s) selected.
 
Mach> delete from tag;
20 row(s) deleted.
 
Mach> select * from tag;
NAME TIME VALUE
--------------------------------------------------------------------------------------
[0] row(s) selected.

Delete ROLLUP Data

Example of deleting rollup data

DELETE FROM TAG ROLLUP BEFORE TO_DATE('Time-string');

if you specify the time of the BEFORE statement, all rollup data before that time are deleted.

if you don’t specify the time of the BEFORE statement, all rollup data is deleted.

Last updated on
Extract tag data