What does MySQL truncate do?
TRUNCATE TABLE empties a table completely. It requires the DROP privilege. Logically, TRUNCATE TABLE is similar to a DELETE statement that deletes all rows, or a sequence of DROP TABLE and CREATE TABLE statements. To achieve high performance, TRUNCATE TABLE bypasses the DML method of deleting data.
How can I get truncated data back in MySQL?
Basically, use mysqlbinlog to dump the contents of that log as a SQL script, then open that script in an editor and delete everything from the TRUNCATE statement to the end. See also https://dev.mysql.com/doc/refman/5.6/en/point-in-time-recovery.html for more tips on using mysqlbinlog for recovery.
What is difference between DELETE and truncate in MySQL?
The DELETE statement removes rows one at a time and records an entry in the transaction log for each deleted row. TRUNCATE TABLE removes the data by deallocating the data pages used to store the table data and records only the page deallocations in the transaction log. 6.
What is truncated in database?
Truncation, also called stemming, is a technique that broadens your search to include various word endings and spellings. To use truncation, enter the root of a word and put the truncation symbol at the end. The database will return results that include any ending of that root word.
Is truncate faster than delete?
TRUNCATE is faster than DELETE , as it doesn’t scan every record before removing it. TRUNCATE TABLE locks the whole table to remove data from a table; thus, this command also uses less transaction space than DELETE .
Is delete DDL or DML?
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.
Can we use TRUNCATE in transaction?
2 Answers. In SQL Server, you can rollback a TRUNCATE from a transaction. It does write page deallocation to the log, as you mentioned. In Oracle, TRUNCATE TABLE is a DDL statement that cannot be used in a transaction (or, more accurately, cannot be rolled back).
Why use truncate instead of 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.
Does truncate free space?
Truncating a table does not give any free space back to the disk – you need to run a SHRINKDATABASE operation for the allocated space to be successfully de-allocated and returned to the disk. Also, as others have mentioned, maybe the table was not taking up much space in the first place.