XML Data Sources

Virtual DataPort allows using XML as data sources. To define an XML data source, it is necessary to specify the access path to the XML document and, optionally, the access path to the file containing the schema or DTD of same.

  • SCHEMA or DTD (optional): Path to the file that contains the metadata of the data source XML file. It may be an XML Schema or a DTD. If it is not specified, Virtual DataPort will try to infer an appropriate schema by analyzing the XML document structure indicated in the next parameter.

  • ROUTE: path to the XML file that represents the data source. See more information about paths to data files in the section Specifying Paths in Virtual DataPort.

  • FILTER: List of filters that will be applied to a file before processing it. They can be applied to the XML file and the XML Schema or DTD (see section Filters)

Syntax of the CREATE DATASOURCE XML statement
    [ FOLDER = <literal> ]
    [ { SCHEMA | DTD } <route> [ <route_filters> ] ]
    ROUTE <route> [ <route_filters> ]
    [ VALIDATE = { TRUE | FALSE } ]
    [ TRANSFER_RATE_FACTOR = <double> ]
    [ DESCRIPTION = <literal> ]

<route_filters> ::= FILTER ( <filter> [, <filter> ]* )

This statement also allows the OR REPLACE clause. In this case, if there is already a data source with the same name, its definition is replaced with the new one.

The syntax of the modification statement of an XML data source is shown below.

Syntax of the ALTER DATASOURCE XML statement
ALTER DATASOURCE XML <name:identifier>
    [ { SCHEMA | DTD } <route> [ <route_filters> ] ]
    [ ROUTE <route> <route_filters> ]
    [ VALIDATE = { TRUE | FALSE } ]
    [ TRANSFER_RATE_FACTOR = <double> ]
    [ DESCRIPTION = <literal> ]

<route_filters> ::=
  FILTER ( <filter> [, <filter> ]* )

Explanation of some of the parameters of these statements:

  • TRANSFER_RATE_FACTOR: relative measure of the speed of the network connection between the Denodo server and the data source. Use the default value (e.g. 1 for JDBC databases located on premises) if the data source is accessible through a conventional 100 Mbps LAN. Use higher values for faster networks and lower values for data sources accessible through a WAN.

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