3.3 Guessing

If ‘-s’ is not given, ffe tries to guess the input structure.

When guessing binary data ffe reads the first block of input data and tries to match the structure definitions from configuration file to that block. The input block size is the maximum binary block size found in configuration file.

When guessing text data ffe reads the first 10 000 lines or 1 MB of input data and tries to match the structure definitions from configuration file to input stream. If all lines match one and only one structure, the structure is used for reading the input file.

Guessing uses following execution cycle:

1. A input line or a binary block is read
2. All record id’s are compared to the input data, if all id’s of a record match the input date and the records line length matches the total length (or total count for separated structure) of the fields, the record is considered to match the input line. If there are no id’s, only the line length or field count is checked. In case of binary data only id’s are used in matching.
3. In case of text data: If all lines match at least one of the records in a particular structure, the structure is considered as selected. There must be only one structure matching all lines used for guessing.

   In case of binary data: If the first block matches at least one record of a structure, the structure is considered as selected. Only one structure must match.

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