Some Oracle SQL should known by Developer - 1

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Interview Questions : DataWareHouse - Part6

What is BUS Schema?
BUS Schema is composed of a master suite of confirmed dimension and standardized definition if facts.

What are the methodologies of Data Warehousing?
Every company has methodology of their own. However, to name a few SDLC Methodology, AIM methodology is standard used.

ETL Testing : Trends & Challenges

ETL Testing : Trends

Count Validation
- Record Count Verification DWH backend/Reporting queries against source and target as a initial check.

Dimensional Validation
Data integrity between the various source tables and relationships. Also we should test the slowly changing dimension as given below. The most common slowly changing dimensions are Types 1, 2, and 3.

Interview Questions : DataWareHouse - Part 4

What are the types of Synonyms?
There are two types of Synonyms Private and Public

What is a Redo Log?
The set of Redo Log files YSDATE, UID, USER or USERENV SQL functions, or the pseudo columns LEVEL or ROWNUM.

What is an Index Segment?
Each Index has an Index segment that stores all of its data.

Explain the relationship among Database, Table space and Data file?
Each databases logically divided into one or more table spaces one or more data files are explicitly created for each table space.

Oracle Interview Questions - Part-2

26. What is hash cluster?
A row is stored in a hash cluster based on the result of applying a hash function to the row’s cluster key value. All rows with the same hash key value are stores together on disk.

27. When can hash cluster used?
Hash clusters are better choice when a table is often queried with equality queries. For such queries the specified cluster key value is hashed. The resulting hash key value points directly to the area on disk that stores the specified rows.

Oracle Interview Questions - Part-1

1. What are the components of physical database structure of Oracle database?
Oracle database is comprised of three types of files. One or more datafiles, two or more redo log files, and one or more control files.

2. What are the components of logical database structure of Oracle database?
There are tablespaces and database’s schema objects.

3. What is a tablespace?
A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.

TeraData HELP command

HELP Command in Teradata plays a important role, This is something like “DESCRIBE” command in Oracle and DB2. This will display the object details.

The HELP Command is used to display information about database objects such as
●     Databases and Users
●     Tables
●     Views
●     Macros

HELP retrieves information about these objects from the Data Dictionary. Below are the syntactical options for various forms of the HELP command: