Teradata

Teradata Utilities

2011-09-15T22:47:00.000-07:00

Teradata loading utilities

The article contains comparison and main features of the data loading tools provided by Teradata. The tutorial illustrates main features of Teradata Multiload , FastLoad and TPump (Parallel Data Pump) and provides sample real-life uses of those tools.

Fast Load

Main use=> To load empty tables at high speed.

The target tables must be empty in order to use FastLoad.

It supports inserts only(not possible to perform updates or deletes in FastLoad).

Although Fastload uses multiple sessions to load the data, only one target table

can be processed at a time.

Teradata Fastload does not support join indexes, foreign key references in target

tables and tables with secondary index defined.

It is necessary to drop any of the constraints listed before loading and recreate

them afterwards.

The maximum number of concurrent Teradata Fastload tasks can be adjusted

by a system administrator.

Fastload runs in two operating modes: Interactive and Batch.

Duplicate rows will not be loaded.

Multi Load

Main use: Load, update and delete large tables in Teradata in a bulk mode

Efficient in loading very large tables.

Multiple tables can be loaded at a time.

Updates data in a database in a block mode (one physical write can update

multiple rows.

Uses table-level locks.

Resource consumption: loading at the highest possible throughput.

Duplicate rows allowed .

TPump

Main use: to load or update a small amount of target table rows

Sends data to a database as a statement which is much slower than using bulk mode

TPump uses row-level hash locks

Resource consumption: loading speed can be adjusted using a built-in resource

consumption management utility. The throughput can be turned down in peak periods.

TPump does not support MULTI-SET tables.

FastLoad(script)

===========================

The following script attached below will load a sample fixed-length columns extract into a Teradata database using FastLoad.

SESSIONS 4;
ERRLIMIT 25;
logon tdpid/username,password;

create table gg_cli (
wh_cust_no integer not null,
cust_name varchar(200),
bal_amt decimal(15,3) format �ZZZ,ZZ9.999�
)
unique primary index( wh_cust_no ) ;

SET RECORD UNFORMATTED;

define
                wh_cust_no(char(10)), delim1(char(1)),
                cust_name(char(200)), delim2(char(1)),
                bal_amt(char(18)), delim3(char(1))
                newlinechar(char(1))
file=insert.input;

SHOW;

BEGIN LOADING gg_cli errorfiles error_1, error_2;

insert into gg_cli (
                :wh_cust_no,
                :cust_name,
                :bal_amt
);

END LOADING;

logoff;

MultiLoad(script)

===========================

The following script attached below will load a sample fixed-length columns extract into a Teradata database using MultiLoad. Use the following command to run load the ggclients.mload file using Teradata FastLoad script:

.logtable inslogtable;

.logon tdpid/username,password;

create table gg_cli (
wh_cust_no integer not null,
cust_name varchar(200),
bal_amt decimal(15,3) format �ZZZ,ZZ9.999�
)
unique primary index( wh_cust_no ) ;

.BEGIN IMPORT MLOAD tables gg_cli;

.layout ggclilayout;
                .field wh_cust_no 1 char(10);
                .field cust_name 12 char(200);
                .field bal_amt 213 char(18);
.dml label insertclidml;

insert into gg_cli.*;

.import infile insert.input
                format text
                layout ggclilayout
                apply insertclidml;
.END MLOAD;

.logoff;

TPump(script)

===========================

The sample script attached below loads a sample fixed-length columns extract into a Teradata database using Parallel Data Pump - Teradata TPump.

.logtable tpumplogtable;
.logon tdpid/username,password;

.BEGIN LOAD SESSION 4;

.layout ggclilayout;
                .field wh_cust_no 1 char(10);
                .field cust_name 12 char(200);
                .field bal_amt 213 char(18);
.dml label insertclidml;

insert into gg_cli.*;

.IMPORT INFILE insert.input
                layout ggclilayout
                apply insertclidml;
.END LOAD;

.logoff;

Stats in Teradata

2011-09-05T22:03:00.000-07:00

Collect stats is a mechanism which helps optimizer to get the least cost execution plan for each requested query.

Collect statistics on table
collect stats on TABLE_NAME;

Collect statistics on column of table
collect stats on TABLE_NAME column(COL1);
collect stats on TABLE_NAME column(COL2);

To get detail about statistics of a table
Help stat DBName.TableName;

Macro in Teradata

2011-09-02T03:19:00.000-07:00

What is macro. What is the difference between macro and procedure.

A macro is the set of sql statements which can be run as a single statement.
          Macro                                                                    Procedure
Macro returns set of data/rows to the user.     It does not return data/rows to the user.
It is allows only input values.                            It provides Input/Output parameter.
It is stored in DBC Perm space.                  It is stored in DATABASE/USER Perm space.

To create a macro:

CREATE MACRO macro_name AS
(SELECT eid, ename FROM emp WHERE deptno=20;);
To execute a macro:
EXEC macro_name;

To create a parametrized macro:
CREATE MACRO macro_name( in_param DATATYPE)
(SELECT eid, ename FROM emp WHERE deptno= :in_param;);
To execute a macro:
EXEC <macro_name> [parameter value list];

Performance Tuning in Teradata

2011-09-01T23:55:00.000-07:00

This post to be released soon.

Introduction of Teradata Database

2011-08-30T06:45:00.000-07:00

The concept of teradata system is little bit different. There is only one database(your teradata system) with lots of (schemas/users). Here (schemas/users) is called database.
In this system dbc is the owner of all metadata. In dbc you can find all the object of teradata.

To get all tables name which consist the particular column.

select tablename, columnname from dbc.columns where columnname ='Emp_Id' and databasename = 'EMPDB';

To see all the objects in a particular database.

Help database databasename;

Index in Teradata

2011-08-30T03:58:00.000-07:00

What is index. How many types of indexes in Teradata.
=> Index is physical mechanism which is used to access and distribute the data rows.
   Indexes help to fast retrieval of data set and useful to data distribution across AMP.

=>There are four main types of indexes in Teradata.
   * Primary Index
   * Secondary Index
   * Join Index
   * Hash Index

=> These indexes divided into following sub category.
   * Unique Primary Index (UPI)
   * Non-Unique Primary Index (NUPI)
   * Partitioned Primary Index(PPI)
   * Non-Partitioned Primary Index(NPPI)
   * Unique Secondary Index (USI)
   * Non-Unique Secondary Index (NUPI)

=> Join Index has six subtypes viz:
   * Single table join index(STJI)
   * Single table aggregate join index(STAJI)
   * Single table sparse join index
   * Multitable simple join index
   * Multitable aggregate join index
   * Multitable sparse join index