- Why truncate is DDL command?
- How many table we can join in SQL?
- What happens to indexes when you truncate a table?
- Does truncate free space?
- Does truncate lock table?
- Does truncate delete table structure?
- What is difference between truncate drop and delete?
- How do I truncate a table in postgresql?
- What happens if we truncate a table?
- How do you truncate a table?
- Can truncate have where condition?
- How do you truncate a table with conditions?
- Does delete query lock table?
- Which is better truncate or delete?
- What is truncate and delete?
- Is truncate a DDL command?
- Does truncating a table reset the identity?
- Which is faster drop or truncate?
- Can we rollback truncate?
- How long does it take to truncate a table?
- How do you delete duplicate rows in SQL?
Why truncate is DDL command?
TRUNCATE resets the high water mark of the table, effectively eliminating all the previously existing rows.
Treating it as a DDL statement allows it to be super-fast, as it allows it to function without retaining undo (rollback) information like DML statements..
How many table we can join in SQL?
Theoretically, there is no upper limit on the number of tables that can be joined using a SELECT statement. (One join condition always combines two tables!) However, the Database Engine has an implementation restriction: the maximum number of tables that can be joined in a SELECT statement is 64.
What happens to indexes when you truncate a table?
When you truncate a table, Oracle Database automatically removes all data in the table’s indexes and any materialized view direct-path INSERT information held in association with the table. This information is independent of any materialized view log.
Does truncate free space?
If you’re using innodb_file_per_table=ON, or you’re using MyISAM, TRUNCATE TABLE will delete the table files used by the table in question (and create new, empty ones). So, the space used will be released to the file system, and in Unix/Linux, “df” on the file system will show new space.
Does truncate lock table?
TRUNCATE is a DDL command. TRUNCATE TABLE always locks the table and page. However, it doesn’t lock each row.
Does truncate delete table structure?
TRUNCATE TABLE is similar to DELETE , but this operation is a DDL (Data Definition Language) command. It also deletes records from a table without removing table structure, but it doesn’t use the WHERE clause.
What is difference between truncate drop and delete?
The DROP command removes a table from the database. All the tables’ rows, indexes, and privileges will also be removed. … 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.
How do I truncate a table in postgresql?
Use the TRUNCATE TABLE statement to delete all data from a large table. Use the CASCADE option to truncate a table and other tables that reference the table via foreign key constraint. The TRUNCATE TABLE does not fire ON DELETE trigger. Instead, it fires the BEFORE TRUNCATE and AFTER TRUNCATE triggers.
What happens if we truncate a table?
TRUNCATE TABLE empties it, but leaves its structure for future data. Removes all rows from a table without logging the individual row deletions. TRUNCATE TABLE is similar to the DELETE statement with no WHERE clause; however, TRUNCATE TABLE is faster and uses fewer system and transaction log resources.
How do you truncate a table?
The SQL TRUNCATE TABLE command is used to delete complete data from an existing table. You can also use DROP TABLE command to delete complete table but it would remove complete table structure form the database and you would need to re-create this table once again if you wish you store some data.
Can truncate have where condition?
TRUNCATE cannot be executed with a WHERE clause means that all records will be removed from the TRUNCATE / statement. However, partitions can be truncated as shown in the below T-SQL statement. From the above statement, partitions 2,4,6,7,8 will be truncated leaving the other partitions data will not be truncated.
How do you truncate a table with conditions?
No, TRUNCATE is all or nothing. You can do a DELETE FROM