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Data cleansing or data cleaning is the process of identifying and correcting (or removing) corrupt, inaccurate, or irrelevant records from a dataset, table, or database.It involves detecting incomplete, incorrect, or inaccurate parts of the data and then replacing, modifying, or deleting the affected data. [1]
Amazon Redshift is a data warehouse product which forms part of the larger cloud-computing platform Amazon Web Services. [1] It is built on top of technology from the massive parallel processing (MPP) data warehouse company ParAccel (later acquired by Actian ), [ 2 ] to handle large scale data sets and database migrations .
Reads from the indexes on the primary instance are read-after-write consistent and users can delete or create new indexes at any time. DocumentDB was an enhancement to the Amazon Aurora relational database system, [5] specifically the PostgreSQL-compatible edition. Its architecture separates storage and computing so that each layer can scale ...
AWS CloudFormation provides a way for users to model an entire AWS infrastructure in a text file, allowing for the infrastructure to be version-controlled, shared, and reused. [8] By using templates, users can create, update, and delete a collection of resources together as a single unit, known as a stack .
Consistent read was a new feature that was released at the same time as conditional put and conditional delete. As the name suggests, consistent read addresses problems that arise due to SimpleDB's eventual consistency model (See the Limitations section). Consider the following sequence of operations: Program A stores some data in SimpleDB.
DELETE requires a shared table lock; Triggers fire; DELETE can be used in the case of: database link; DELETE returns the number of records deleted; Transaction log - DELETE needs to read records, check constraints, update block, update indexes, and generate redo / undo. All of this takes time, hence it takes time much longer than with TRUNCATE
Cursors can not only be used to fetch data from the DBMS into an application but also to identify a row in a table to be updated or deleted. The SQL:2003 standard defines positioned update and positioned delete SQL statements for that purpose. Such statements do not use a regular WHERE clause with predicates. Instead, a cursor identifies the row.
A Primary Key is a set of attributes that uniquely identifies items in a DynamoDB Table. Creation of a DynamoDB Table requires definition of a Primary Key. Each item in a DynamoDB Table is required to have all of the attributes that constitute the Primary Key, and no two items in a Table can have the same Primary Key.