MockRecordReader

Drill provides a mock record reader to generate test data in the package: org.apache.drill.exec.store.mock.

Mock data is available for physical plans. Here is a typical example:

       {
            @id:1,
            pop:"mock-scan",
            url: "http://apache.org",
            entries:[
                {records: 1000000, types: [
                  {name: "blue", type: "INT", mode: "REQUIRED"},
                  {name: "green", type: "INT", mode: "REQUIRED"}
                ]}
            ]
        },

The JSON fields are:

• @id: Standard required Physical OPerator (pop) ID.
• pop: Must be "mock-scan"
• url: Unused
• entries: A list of schemas of the files to generate.

The scanner supports parallelization based on the number of entries.

The fields for the schema are:

• records: The number of records to generate.
• types: A list of columns (the “types” name is a misnomer.)

Field schema fields include:

• name: Field name
• type: The Drill minor type as defined in MinorType.
• mode: The cardinality (mode) as defined in DataMode: OPTIONAL, REQUIRED or REPEATED.
• width: Optional field width (need only for variable-size types such as VARCHAR.)