Teradata indexes with examples

Teradata acquired aster data systems to buy their way into the nosql section of the big data world. This book includes over examples of all aspects of sql starting at the most basic level and going to the most advanced level with real examples that work and explain exactly what is going on. Purpose creates a secondary index on an existing data table or join index. Drop index is supported in teradata syntax as well as odbc syntax for locally created index names. Nov 06, 2016 this video explains the basics of teradata data distribution and introduction to primary index. This manual describes the oracle database gateway for teradata, which enables oracle client applications to access teradata data through structured query language sql. The tutorial illustrates main features of teradata multiload, fastload and tpump parallel data pump and provides sample reallife uses of those tools. Creating a partitioned primary index to improve performance.

Create index is supported in odbc syntax as well as in teradata syntax. In fact, it is by far the most important of all teradata indexes. All you can do is to make a copy of a table without an index. List tables indexes in teradata teradata sql server. Indexes on tables in a relational database function much like indexes in books, they speed up information retrieval. Each table in teradata is required to have a primary index defined. Simple answer you cant disable and reenable indexes in teradata. The gateway, with the oracle database, creates the appearance that all data resides on a local oracle database, even though the data can be widely distributed. May 28, 2014 the teradata hash index can help you to reduce system workload. Teradata keeps all collect statistics information in dbc in the data dictionary tables. A multitable join index is created by joining more than one table. Access to a teradata environment on which to execute queries. Indexes are used to retrieve data from the database more quickly than otherwise. The extent of improvement can be dramatic, especially for queries involving complex, largetable, and multipletable joins.

Partitioning can be done on volatile,global temporary and permanent tables. Unique secondary index usi as the name suggest, usi enforces uniqueness on a column or group of column values. Tvfields for all columns and single column indexes. The first chapter of the teradata indexes book focuses on the primary index pi, as you would probably expect if you knew even a little about teradata, and teradata indexes in particular. By looking at the longest running queries and running them through a query plan generator we realized the database could benefit from a new index. The following example creates the salary table with column employeeno as unique primary index. The following example displays a list of projects in which the word batch appears in the project description, and lists the starting position of the word. Teradata data loading tools multiload, fastload and tpump. It is still only one primary index, but it is merely made up by combining multiple columns together. Usi access is atmost a twoamp operation and will return atmost single row. You create secondary indexes explicitly using the create table and create index statements. Secondary index is not involved in data distribution.

The optimizer uses the synopsis data to generate the table access and join plans. Examples of creating and updating secondary index in teradata rdbms access data using secondary index if a teradata sql request uses secondary index values in a where constraint, the optimizer may use the rowid in a secondary index subtable to access the qualifying rows in the data table. If the primary index is not defined, teradata automatically assigns the primary index. The purpose of collect statistics is to gather and store demographic data for one or more columns or indices of a table or join index. Below is an example of a singletable aggregate join index. Select databasename, tablename, columnname, indextype, indexnumber, indexname from dices order by databasename, tablename, indexnumber. In this process it collects data and stores the summary in the data dictionary dd inside user dbc. Collect statistics statement is collects the demographic data for one or more columns,hash indexes, join indexes of the table and stores the synopsis in the data dictionary. Create unique indexemployeeno on employee non unique secondary. Boost your teradata system performance by adding the join index to your indexing portfolio. Teradata vantage sql fundamentals, b0351141 provides an overview of secondary indexes, while teradata vantage database design, b0351094 provides more detail.

I till 64 columnsapi is composite till 64 column if is physical mechanism to assign a row to amp. Index function in teradata extension in teradata tutorial 26. The following example creates usi on employeeno column of employee table. Oct 11, 2015 list tables indexes in teradata getting all tables indexes in teradata studio is not quite a straightforward process. Vldb apps cloud data teradata indexes primary index. There are a few more join indexes that can be used in teradata. Teradata database sql data definition language syntax and examples release. The extent of such improvement depends on how often an index is appropriate to a query. A ppi partitioned primary index is a type of index that enables users to set up databases that provide performance benefits from a data locality, while retaining the benefits of scalability inherent in the hash architecture of the teradata database.

Secondary indexes secondary indexes are never required for teradata database tables, but they can often improve system performance. In this tutorial, we will create solutions to design indexes to help us improve query performance of teradata database management system. The teradata timestamp can be set to a different time zone systemwide, per user or per column using with time zone. Primary index in general, all teradata database tables require a primary index because the system distributes tables on their primary indexes.

Secondary indexes are an alternate path to access the data. The create index statement is used to create indexes in tables. A secondary index can be defined as a unique secondary index usi or nonunique secondary index nusi. Continues the discussion of utilizing indexes in teradata and provides numerous examples of using indexes to gain optimal access and performance. This video explains the basics of teradata data distribution and introduction to primary index. List tables indexes in teradata getting all tables indexes in teradata studio is not quite a straightforward process. Drop index if you talking about pi primary index you cant drop it. Which teradata load protocol do we use to load our data. The following example creates the empupi table with column empid as. Join index is stored in the permanent space and maintained by the system automatically. Primary index provides the fastest way to access the data. The samples are split into eleven distinct modules. Since secondary indexes require subtables, these subtables require additional disk space and, therefore, may require additional ios for inserts, deletes, and updates.

Its been few years since i have been working on hive, impala, spark sql, pyspark, redshift and in the journey so far i have migrated many applications in different rdbms like teradata, netezza, oracle to cloud or onpremise hadoop environment for various clients. Teradata will create subtable on each amp once you create the usi on a column or group of columns. The teradata hash index can help you to reduce system workload. Generally, secondary index are defined on column values frequently used in where constraints. For your reference, please find below the indexes used in teradata. Jun 11, 2018 covering indexes improve the speed of join queries. List table indexes in teradata database teradata data dictionary. Teradata renamed the offering as teradata aster after the acquisition. Teradata join index achieve better performance now. You can define join index in teradata on single or multiple tables. Odbc learning examples tier 2 is a suite of applications designed to provide an informative guide to developing odbc applications as well as providing simple building blocks for odbc applications. For example, the optimizer may consider using a covering index instead of. The next example creates a unique secondary indexusi. Secondary indexes are stored in separate subtables that requires additional disk.

Both multitable and singletable simple join indexes can also be sparse, for example. This function worked before there was a defined standard command to provide this functionality. Index function in teradata extension in teradata tutorial 01. In the teradata rdbms, an index is used to define row uniqueness and retrieve data. This post gives you all the details you need for your indexing strategy. Apr 09, 2020 both teradata and bigquery data types are usually associated with a utc time zone. Therefore its always handy to have a query to dbc database available. Examples of creating and updating secondary index in teradata rdbms. To find out the list of indexes used in teradata forget code. Clustered and nonclustered indexes in sql server part 36. Teradata allows more than one column to be designated as the primary index. You cannot fire any query on the join index directly. The next example creates a unique secondary index usi. Can be defined to create a partial or full replication of base table with a different primary index.

In our example, each amp holds the name column for all employee rows in. I was once working on a database where a series of operations took about eight days to complete. By rendering the following query, you can find the list of indexes. Nov 19, 2019 the teradata knowledge site teradata join index achieve better performance now. The article contains comparison and main features of the data loading tools provided by teradata. The users cannot see the indexes, they are just used to speed up searchesqueries. Teradata partition primary indexppi ppi characteristics. Index examines the name field and returns all names where a space appears in a character position beyond the sixth character position seven or higher. Multitable join index can be used to store the result set of frequently joined tables to improve the performance. Mar 11, 2011 the same hash index definition could have been abbreviated as follows. How do teradata indexes affect our choice of load protocol. Secondary index secondary indexes can be unique or nonunique. Dec, 2010 sparse index sparse join index it is type of join index which contains a where clause, that reduces number of rows participating from the base tables. A join index composed of virtual rows, with multiple fixed column sets.

There are some differences between the primary index and the secondary index. An index is a physical mechanism used to store and access the rows of a table. Teradata database can implicitly create unique secondary indexes. All types of join indexes, including single table, multitable, simple or aggregate can be sparse. Teradata will perform full table scan for those queries. Teradata maintains separate subtable for each secondary index. Teradata basics training database courses webucator. Since we are not specifying the word unique, the above index will be treated as non unique secondary index. And like the folks before said, figure out how all the tables relate to each other and the type of questions you plan to ask of your data. The purpose of this documentation is to provide examples of programs that can be used as a guide for purposes of developing jdbc applications solely for use with the database, and is provided as an illustration of how jdbc functions operate with the database. The bigquery timestamp type assumes utc if you dont explicitly specify a time zone.

Teradata has always been doing big data, but traditionally with sql rdbmsbased oltp and olap systems features of teradata. The building block approach that continues to take things a step deeper at a time makes this a perfect sql guide for everyone. Performance tuning using collect statistics in teradata table. Examples of using partitioning and secondary indexes with join indexes are provided. Teradata basics training print in this course, students will learn the basics of teradata architecture with a focus on whats important to know from an it and developer perspective. The teradata join index stores prejoined tables, the result of aggregations.