EDOBE XDOM PMML Manuel d'utilisateur télécharger pdf (Page 18)

Date

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 date values.

Output Caches The pipeline is designed to pass blocks of data between components,

rather than passing all of the data at once. It is this capability that

allows the product to scale to handle a very large number of rows of

data.

Global and component level settings are available to determine

whether a copy of the data is stored for each node output. By default,

each computed output has a corresponding copy of the data in an

output cache file.

If all of the computations can be performed in a blockwise fashion

with a single pass through the data, all of the data can be passed from

node to node without storing the values. This would be the case in a

network containing a series of Read Text File, Create Columns,

and Write Text File nodes. The advantage of not caching output

values is a savings in file space usage.

The advantage of caching values is that it provides greater

interactivity. Additional components can be hooked to an output and

executed without having to recompute the previous component

outputs. The data at the output can also be viewed in the viewer.

This interactivity is the reason the product caches node outputs by

default.

Some computational components cannot operate in a blockwise

fashion with a single pass through the data. For example, logistic

regression needs to make multiple passes through the data as it

performs numerical optimization. For this type of node, the

preceding output caches corresponding to its inputs will be created

regardless of the cache settings.

Node State Each node is always in one of three states: created, configured, or

computed.

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EDOBE XDOM PMML Manuel d'utilisateur Page 18