db.data.frame-class: Class '"db.data.frame"'

In greenplum-db/GreenplumR: A Fast, Easy-to-Use Tool for Manipulating Tables in Databases

Class "db.data.frame"

Description

An object of this class points to a real table/view in the database. No data is transfered into R. Only a minimal amount of information is kept in the object.

Objects from the Class

Objects can be created by calls of db.data.frame or as.db.data.frame.

The object represents a real table/view in the database. Usually it is NOT recommended to directly manipulate the internal slots of these objects.

Slots

.name:

Object of class "character". It is the table name if this db.data.frame was created using just a table name. It can also be a two-element array if this db.data.frame was created. This slot is obsolete.

.content:

Object of class "character". The table name. The function content can get this value.

.conn.id:

Object of class "numeric", an integer. The ID number of the database connection where the table resides. The functions conn.id and conn.id<- can get and set this value.

.col.name:

Object of class "character". The 1D array of column names of the table/view that this db.data.frame points to. The S4 method names,db.obj-method

gets this value.

.col.data_type:

Object of class "character". The 1D array of column data types of the table/view that this db.data.frame points to. This is not supposed to be used by the normal user.

.col.udt_name:

Object of class "character". The 1D array of column udt names of the table/view that this db.data.frame points to. This is not to used by normal users.

.table.type:

Object of class "character". The information about the type of tha table/view that this db.data.frame points to, for example, "BASE TABLE", "VIEW" or "LOCAL TEMPORARY".

.is.factor:

Object of class "logical". An array of logical values which indicate whether each column of the table/view is a factor. This is not to be used by the normal users.

.factor.suffix:

Object of class "character". An array of strings for every column. When creating dummy columns for a factor column, we add a random string in the names of the dummy columns to avoid naming conflicts. So a factor column's .factor.suffix is a random string, otherwise it is just an empty string. This is not to be used by the normal users.

.factor.ref:

The value of the factor reference level for the regressions. If it is NA, then the regressions automatically select a reference level.

.appear.name:

Object of class "character". This is not to be used by the normal users.

.dummy:

Object of class "character". An array of strings, The dummy column names which are used only for factor support.

.dummy.expr:

Object of class "character". The SQL expressions used to create dummy column names which are used only for factor support.

.dist.by:

A string, the distribution policy when using Greenplum database or HAWQ. It can be character(0), which means the data table is distributed randomly. Or it can be a string of column names separated by comma, which are the columns that are used in the "distributed by" when the table was created.

Extends

Class db.obj, directly.

Methods

Aggregate functions, by,db.obj-method, dim,db.table-method, dim,db.view-method, dim,db.Rquery-method, names,db.obj-method, conn.id, conn.id<-, eql, key, key<-, merge,db.obj,db.obj-method, print,db.data.frame-method, show,db.data.frame-method, sort,db.obj-method, subset,db.obj-method, Arith methods, Compare methods, Logical methods, Extraction methods, Replacement methods

Author(s)

Author: Predictive Analytics Team at Pivotal Inc.

Maintainer: Frank McQuillan, Pivotal Inc. [e-mail]

See Also

db.data.frame creates a db.data.frame object.

as.db.data.frame converts db.Rquery object, data.frame, or a data file into a db.data.frame object and at the same time creates a new table in the database.

db.obj is the superclass.

db.table and db.view are the sub-classes.

db.Rquery is another sub-class of db.obj.

lk or lookat display a part of the table

Examples

## Not run: 
showClass("db.data.frame")



## set up the database connection
## Assume that .port is port number and .dbname is the database name
cid <- db.connect(port = .port, dbname = .dbname, verbose = FALSE)

delete("abalone", conn.id = cid)
as.db.data.frame(abalone, "abalone", conn.id = cid, verbose = FALSE)
x <- db.data.frame("abalone", conn.id = cid, verbose = FALSE) # x points to table "abalone"

lk(x)

db.disconnect(cid, verbose = FALSE)

## End(Not run)

greenplum-db/GreenplumR documentation built on Sept. 2, 2023, 8:09 a.m.