Timestamp function
timestamp(columnName)
elects a
designated timestamp:
- during a CREATE TABLE operation
- during a SELECT operation (
dynamic timestamp
)
#
Syntax#
During a CREATE operationCreate a designated timestamp column during table creation. For more information, refer to the CREATE TABLE section.
#
During a SELECT operationCreates a designated timestamp column in the result of a query.
caution
The output query must be ordered by time. TIMESTAMP()
does not check for order
and using timestamp functions on unordered data may produce unexpected results.
tip
Dynamic timestamp allows to perform time series operations such as LATEST BY
,
SAMPLE BY
or LATEST BY
on tables which do not have a designated timestamp
.
#
Examples#
During a CREATE operationThe following creates a table with designated timestamp.
#
During a SELECT operationThe following will query a table and assign a
designated timestamp to the output. Note
the use of brackets to ensure the timestamp clause is applied to the result of
the query instead of the whole readings
table.
Although the readings
table does not have a designated timestamp, we are able
to create one on the fly. Now, we can use this into a subquery to perform
timestamp operations.
If the data is unordered, it is important to order it first.