What are metadata tables?

What are metadata tables?

Metadata tables provide the data definitions for the source data that is being consumed by the operational server. These tables provide the basic information to associate the source data to the member data.

What is metadata in SQL database?

Metadata, as most of you may already know, provides the basic and relevant information about the data. Metadata functions in SQL Server return information about the database, database objects, database files, file groups etc. in SQL Server.

How can I see table details in Teradata?

In my Teradata SQL Assistant Client, I can right-click a table and select Show Definition, this will display the column types and how they are defined.

How do I get table schema in Teradata?

You can use SHOW TABLE to display the table definition for a PTI table. The output includes the system generated TD_TIMEBUCKET, TD_TIMECODE, and TD_SEQNO columns for PTI Tables. For complete information about SHOW TABLE syntax, see Teradata Vantage™ SQL Data Definition Language Syntax and Examples , B035-1144.

How do I see SQL table metadata?

There are 2 simple ways:

1. Option 1. sp_help ‘schema.table_name’
2. Option 2. SELECT * FROM INFORMATION_SCHEMA.columns c WHERE c.table_name = ‘table_name’

How do I get the metadata from a table in SQL?

Using the Information Schema

1. SELECT TABLE_NAME FROM INFORMATION_SCHEMA. TABLES.
2. SELECT TABLE_NAME, COLUMN_NAME FROM INFORMATION_SCHEMA. COLUMNS.
3. SELECT COLUMN_NAME FROM INFORMATION_SCHEMA. COLUMNS WHERE TABLE_NAME = ‘Album’
4. IF EXISTS( SELECT * FROM INFORMATION_SCHEMA.
5. IF EXISTS( SELECT * FROM INFORMATION_SCHEMA.

What are DBC tables in Teradata?

Teradata data dictionary tables are metadata tables present in the DBC database. It can be used for variety of things such as checking table size, query bottleneck and database size etc. Dbc. Columns : Column informatiom of tables, views, join index & hash index etc.

How do you create a table statement in Teradata?

Following is the generic syntax of CREATE TABLE statement. CREATE TABLE

What is DBC table Teradata?

What is DBC in Teradata?

The DBC/1012 Data Base Computer was introduced by Teradata Corporation in 1984, as a back-end data base management system for mainframe computers.

What are the 4 types of metadata?

Metadata Types There are three main types of metadata: descriptive, administrative, and structural. Descriptive metadata enables discovery, identification, and selection of resources. It can include elements such as title, author, and subjects.

How to execute multiple queries in Teradata?

Teradata enables you to check last query executed by specific user. To list sessions: List active sessions. Notes. To log query information you need to create rules for logs. To do this use BEGIN QUERY LOGGING statement. You can find out how to use it in teradata documentation. Example statement to log all queries: BEGIN QUERY LOGGING ON ALL; Query

How to optimize a Teradata query?

First of all use EXPLAIN plan to see how the query is performing.

Keywords like Product joins,low confidence are measures of poor performance.

Make Sure,STATS are collected on the columns used in WHERE Clause and JOIN columns.

How to check the table size using query in Teradata?

Teradata. How much space are your tables using? You can measure the space used by the tables in bytes across databases. Syntax: SELECT tablename,sum(currentperm)/1024*1024 Bytes_usage. FROM dbc.allspace. WHERE databasename=’your_database_name’. GROUP BY 1.

How to measure SQL query performance in Teradata?

Non-indexed columns used in predicates: Missing statistics force the Optimizer to do a very inaccurate heuristic estimation.

Skewed indexed columns: Random AMP sampling on skewed index results in wrong estimates and execution plans.

Small tables: Estimations for small tables suck when there are fewer table rows than AMPs.