PowerExchange for Cassandra User Guide

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Virtual Table Operations Examples

The example mappings illustrate the operations that you can perform on a virtual table.

The login details of users are stored in a Cassandra column family. You need to read, insert, update, append, or delete values from the location column.

The following users_list table represents a Cassandra column family that contains a collection of type list:

username	first_name	last_name	city	last_login	location
user1	john	doe	SFO	2014-8-03 01:30:00	0.0.0.0, 123.123.123.2
user2	jane	smith	NYC	2014-8-03 01:40:00	123.88.99.2, 0.0.0.0
user3	brian	lee	SFO	2014-8-04 11:15:00	123.123.2.2, 127.0.0.0
user4	james	adam	NYC	2014-8-05 05:22:00	123.123.1.2, 127.0.0.0

The Informatica Cassandra ODBC driver creates the users_list main table and users_list_vt_location virtual table.

The following image displays the users_list main table:

The image shows the data preview of a source table for a list collection.

The following image displays the users_list_vt_location virtual table:

The image shows the data preview of the virtual table for a list collection.

The following example mappings and data preview illustrate the virtual table operations:

Read Operation: The following image displays the data preview of the users_list_vt_location virtual table:
Insert Operation: The following pass-through mapping inserts rows into a virtual table:

The mapping source is the users_list_vt_location table. The mapping target is the users_list_tgt_vt_location table.

The following image displays the data preview of the target virtual table:
Update Operation: You can use a DD_UPDATE constant in an Update Strategy transformation to update rows in a virtual table.
The following mapping uses an Update Strategy transformation to update rows in a virtual table:

The mapping source is the users_list_vt_location table. The DD_UPDATE constant in the Update Strategy transformation updates rows in the target virtual table. The mapping target is the users_list_tgt_vt_location table.
Append Operation: You can append rows only to virtual tables created for list type.
The following mapping appends the location value to each user in the list in the users_list_tgt_vt_location table:

The mapping source is the users_list_vt_location table. The Expression transformation sets the list index to -1. The mapping target is the users_list_tgt_vt_location table.

The following image displays a data preview of the rows in the target table before you append rows in the target table:

The following image displays a data preview of the rows appended in the target virtual table:
Delete Operation: You can use a DD_DELETE constant in an Update Strategy transformation to delete rows from a virtual table.
The following mapping uses an Update Strategy transformation to delete rows from a virtual table:

The mapping source is the users_list_vt_location table. The DD_DELETE constant in the Update Strategy transformation deletes rows from the target virtual table. The mapping target is the users_list_tgt_vt_location table.

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PowerExchange for Cassandra User Guide

PowerExchange for Cassandra User Guide

Virtual Table Operations Examples

Virtual Table Operations Examples