What is the difference between TRUNCATE DELETE and DROP?

What is the difference between TRUNCATE DELETE and DROP?

DROP statement is a Data Definition Language(DDL) Command which is used to delete existing database objects. Unlike TRUNCATE which only deletes the data of the tables, the DROP command deletes the data of the table as well as removes the entire schema/structure of the table from the database.

How do you TRUNCATE a staging table?

DROP vs DELETE vs TRUNCATE for staging data

1. Load the data into staging stable, mark this data as new, load only marked data into target, unmark data.
2. Delete all data in staging, load the data into staging table, load all data into target.
3. Truncate staging table, load into staging, load into target.

Can delete and TRUNCATE be reversed?

DROP and TRUNCATE are DDL commands, whereas DELETE is a DML command. DELETE operations can be rolled back (undone), while DROP and TRUNCATE operations cannot be rolled back.

Does TRUNCATE DELETE table structure?

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.

Is DROP table expensive?

2 Answers. DROP & CREATE is slightly more expensive, as it actually deletes rows from some system tables ( pg_class , pg_attribute .) in addition to removing the physical table files – and later has to parse etc.

What is truncate and load in ETL?

Truncate & Load: The target table is deleted completely first, and all data records from source system is inserted afresh. Delta Load: Here, the source data records are first checked for changes i.e. New records inserted and Old records updated.

What’s the difference between drop, truncate and delete?

DROP is a DDL Command. Objects deleted using DROP are permanently lost and it cannot be rolled back. Unlike TRUNCATE which only deletes the data of the tables, the DROP command deletes the data of the table as well as removes the entire schema/structure of the table from the database.

Which is faster to delete or truncate a table?

To remove specific rows, use DELETE. To remove all rows from a large table and leave the table structure, use TRUNCATE TABLE. It’s faster than DELETE. To remove an entire table, including its structure and data, use DROP TABLE.

How to delete all data in staging table?

Delete all data in staging, load the data into staging table, load all data into target. Drop staging table, create staging table, laod into staging table, load into target. Drop staging database, create staging table, load into staging table, load into target.

Can a drop table be used to delete a table?

The DROP TABLE is another DDL (Data Definition Language) operation. But it is not used for simply removing data from a table; it deletes the table structure from the database, along with any data stored in the table. All you need after DROP TABLE is the name of the table you want to delete.