The imdc_adapter function outputs data from a specified IMDC. This output can be input to another SQL-MapReduce function by an input iterator. This technique enables the receiving SQL-MapReduce function to use IMDCs even if it was not coded to use them.
Conceptually, imdc_adapter is a combination of load_into_imdc and project_from_imdc. However, while load_into_imdc fails if the specified IMDC does not exist, imdc_adapter creates the IMDC and loads it with data from its input.
Syntax
SELECT * FROM imdc_adapter ( input imdc (imdc_name) [ imdcInMemSizeInMB ('memory_size') ] );
Input
One or more sources of data to load into the IMDC. The inputs must meet the Semantic Requirements for SQL-MapReduce Functions.
If the IMDC exists, the function substitutes the empty table NC_SYSTEM.NC_DUMMY for the inputs that you provide. For details, see Optimization When IMDC Exists.
Arguments
- imdc
- Specifies the name of the IMDC whose data is to be output. If the specified IMDC does not exist, the function creates it and loads it with data from its inputs.
- imdcInMemSizeInMB
- [Optional. Ignored if the specified IMDC exists.] Specifies amount of memory (MB) for the IMDC to use for each partition. Default: 16 MB for a fact table, 99 MB for a dimension table.
Schema of Output IMDC
If the input IMDC exists, the schema of the output IMDC is the same as that of the input IMDC.
If the input IMDC does not exist, the schema of the output IMDC is the same as that of the input table.