EDOBE XDOM PMML Manual de usuario Pagina 53

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String
String columns are used for informational columns such as names or
addresses that do not represent categories and are not used in
computations. The actual string value is stored separately for each
row. The number of characters stored can be set for each column.
The underlying pipeline can handle full Unicode multibyte
characters. However, the import/export library used by Spotfire
Miner only supports 8-byte ASCII. This includes all of the characters
in most Romance languages, but not the full character sets for some
Asian languages.
The string width value actually specifies the number of bytes used.
Multibyte characters may use more than one byte per character, in
which case the number of characters that can be stored for a string
will be less than the string width setting.
Time/Date
Time/Date columns are used to represent dates and times. They are
stored as a long representing the number of milliseconds since an
origin of January 1, 1970. This is the same origin used by Java. A
string representation of the time is used for display. Options under
Tools:Options specify the default date formats for reading and
displaying time/date values.
Buf Objects A buf object represents a data buffer with N rows by P columns. The
number of rows, number of columns, their names, and their data
types are determined when the buf is created. The actual storage in a
buf is allocated when the buf is initialized.
A buf object acts like a circular buffer. One proc can write a series of
rows of data into a buf, and one or more procs can read this data, in
order. As a proc reads a chunk of data from a buf, it releases the
chunk. Only when all reading procs have released a chunk of data is
the space available to be filled by newly-written rows.
It is very important that the bufs be sized large enough. Before a proc
can run, it needs to reserve a chunk of data from its input bufs, as well
as the space for its output data in its output bufs. While a proc is
executing, it cannot allocate more space from its output bufs.
Therefore, if a buf is too small, you can have a situation where a
reading proc cannot execute (because its input buf doesn't have
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