Storing R objects in database tables

The Netezza R library allows you to store serialized versions of your objects in database tables. As Netezza does not support large objects (LOBS), objects are stored across several database rows. To make management of such objects easier, the nzr package introduces the object class nz.list.

nz.list is aligned with lists in R, although objects are stored remotely instead of locally. An nz.list object is a reference to a specially formatted database table.

To create an nz.list, you can use the following command:

nzl <- nz.list("MYNEWLIST",createTable=T, indexType="character");

This command creates a table MYNEWLIST and a local stub object nzl. The indexType character parameter indicates that the index column for the list is represented by varchar in the database. The indexType integer would use an integer column for this purpose.

Objects can be stored to the remote list by using the [] and $ operators.

#Store an object
nzl['myKey'] ← 1:100000
nzl$myKey ← 1:100000
#Read an object
nzl['myKey']
nzl$myKey
#Delete an object
nzl['myKey'] ← NULL
nzl$myKey ← NULL

Note: The names function returns all the keys in a list; the length function returns the length of a list.

The following arguments are used with the nz.list constructor:

tableName: Specifies the name of the database table containing the list. This can be an existing table or a new one.
createTable: Optional. If TRUE, a new table is created if it does not yet exist.
indexType: If a new table is created, it indicates the type of index to use, integer or character.