You can create an empty or populated time series that also
contains user-defined metadata. A time series column includes a header
that holds information about the time series and can also contain
user-defined metadata.
About this task
User-defined metadata allows the time series to be self-describing.
The metadata can be information usually contained in additional columns
in the table, such as the name of a stock, or the type of the time
series. The advantage of keeping this type of information in the time
series is that, when using an API routine, it is easier to retrieve
the metadata than to pass additional columns to the routine. Metadata
is stored in a distinct type based on the TimeSeriesMeta data
type. The TimeSeriesMeta data type is an opaque data type of
variable length, up to a maximum length of 512 bytes. The routines
that accept the TimeSeriesMeta data type also accept its distinct
type. The distinct type requires support functions, such as input,
output, send, receive, and so on.
Procedure
To create a time series with metadata:
- Create a distinct data type based on the TimeSeriesMeta data
type with the following SQL statement. Substitute MyMetaData with
a name you choose.
create distinct type MyMetaData as
TimeSeriesMeta
- Create support functions for your metadata data type.
For information on creating support functions, see the HCL OneDB™ User-Defined Routines
and Data Types Developer's Guide.
- Run the TSCreate or TSCreateIrr function
with the metadata argument.
Results
After you have created a time series with metadata, you
can add, change, remove, and retrieve the metadata. You can also retrieve
the name of your metadata type.