Should you ever delete data from database?

Should you ever delete data from database?

Actual database performance may not require deleting data, unless the data sets are huge. Even a table with millions of rows and dozens of columns may not need deleting if you partition it properly and ensure your queries always use the proper partitions.

How do you hard delete a database?

Hard Delete

1. Involves directly deleting the data row from the table.
2. Many a times, the data (or action) is copied onto an audit table to assist in possible debugging in the future.
3. This copying can be done with one of the following options : Listener code in the application (observer pattern) Database Trigger.

Is it possible to delete data in database management system?

A subset may be defined for deletion using a condition, otherwise all records are removed. Some database management systems (DBMSs), like MySQL, allow deletion of rows from multiple tables with one DELETE statement (this is sometimes called multi-table DELETE).

What is truncate in database?

TRUNCATE TABLE removes all rows from a table, but the table structure and its columns, constraints, indexes, and so on remain. To remove the table definition in addition to its data, use the DROP TABLE statement.

How do I clean up my SQL database?

1. Join.
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How do you do a soft delete in SQL?

Think of the cycle:

1. create user (login=JOE)
2. soft-delete (set deleted column to non-null.)
3. (re) create user (login=JOE). ERROR. LOGIN=JOE is already taken.

What is soft delete in database?

“Soft delete” in database lingo means that you set a flag on an existing table which indicates that a record has been deleted, instead of actually deleting the record.

Why we do soft delete?

Soft deletion is a widely used pattern applied for business applications. It allows you to mark some records as deleted without actual erasure from the database. Effectively, you prevent a soft-deleted record from being selected, meanwhile, all old records can still refer to it.

Can delete be rolled back?

DELETE is a DML Command so it can be rolled back. The DELETE command returns the number of records that were deleted by its execution.

Which is better truncate or delete?

Truncate removes all records and doesn’t fire triggers. Truncate is faster compared to delete as it makes less use of the transaction log. Truncate is not possible when a table is referenced by a Foreign Key or tables are used in replication or with indexed views.

What are the disadvantages of deleting an existing database?

NOTE − Be careful before using this operation because by deleting an existing database would result in loss of complete information stored in the database. Make sure you have the admin privilege before dropping any database.

Do I have to delete data?

In certain circumstances you MUST delete data, an example being anything relating to a users personal information. EU Law (and possibly others) state that a user should have the right to request that their data be removed. In such a case this data must be deleted, and not simply flagged as no longer active.

Is it possible to recover deleted data from a database?

As with all these things the answer is “it depends”. If the user is ever likely to want the data back then your friends are right – you don’t really delete just mark the record as “deleted”. This way when the user changes their mind you can recover the data.

What happens to deleted records when a database is compacted?

When the DB needs to write a new record, it will likely (if the space is sized correctly) try to write over top of one of these areas, rather than increase the size of the database. Compacting and Repairing the database, amongst other things, removes all of these deleted records from the database. Which leads to the question.