Difference between drop table and truncate table

Question

I have some tables that I build as a part of my report rollup  I don t need them afterwards at all  Someone mentioned to truncate them as it would be faster

User · Answer

DELETE

The DELETE command is used to remove rows from a table. A WHERE clause can be used to only remove some rows. If no WHERE condition is specified, all rows will be removed. After performing a DELETE operation you need to COMMIT or ROLLBACK the transaction to make the change permanent or to undo it.

TRUNCATE

TRUNCATE removes all rows from a table. The operation cannot be rolled back ... As such, TRUCATE is faster and doesn't use as much undo space as a DELETE.

From: http://www.orafaq.com/faq/difference_between_truncate_delete_and_drop_commands

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Drop drop whole table and all its structure  truncate delete all rows from table  it is different from delete that it also delete indexes of rows

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Truncating the table empties the table  Dropping the table deletes it entirely  Either one will be fast  but dropping it will likely be faster  depending on your database engine    If you don t need it anymore  drop it so it s not cluttering up your schema

User · Answer

DROP TABLE deletes the table   TRUNCATE TABLE empties it  but leaves its structure for future data

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I have a correction for one of the statements above     truncate cannot be rolled back   Truncate can be rolled back   There are some cases when you can t do a truncate or drop table  such as when you have a foreign key reference   For a task such as monthly reporting  I d probably just drop the table once I didn t need it anymore   If I was doing this rollup reporting more often then I d probably keep the table instead and use truncate   Hope this helps  here s some more info that you should find useful     Please see the following article for more details  http   sqlblog com blogs denis gobo archive 2007 06 13 1458 aspx  Also  for more details on delete vs  truncate  see this article  http   www sql-server-performance com faq delete truncate difference p1 aspx  Thanks  Jeff

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TRUNCATE TABLE keeps all of your old indexing and whatnot   DROP TABLE would  obviously  get rid of the table and require you to recreate it later

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In the SQL standard  DROP table removes the table and the table schema - TRUNCATE removes all rows

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Drop gets rid of the table completely  removing the definition as well   Truncate empties the table but does not get rid of the definition

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DROP Table  DROP TABLE  table name        The DROP command is used to remove a table from the database  It is a DDL command  All the rows  indexes and privileges of the table will also be removed  DROP operation cannot be rolled back    DELETE Table  DELETE FROM  table name  WHERE  condition    DELETE FROM  table name        The DELETE command is a DML command  It can be used to delete all the rows or some rows from the table based on the condition specified in WHERE clause  It is executed using a row lock  each row in the table is locked for deletion  It maintain the transaction log  so it is slower than TRUNCATE    DELETE operations can be rolled back    TRUNCATE Table  TRUNCATE TABLE  table name        The TRUNCATE command removes all rows from a table  It won t log the deletion of each row  instead it logs the deallocation of the data pages of the table  which makes it faster than DELETE  It is executed using a table lock and whole table is locked for remove all records  It is a DDL command  TRUNCATE operations cannot be rolled back

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Deleting records from a table logs every deletion and executes delete triggers for the records deleted  Truncate is a more powerful command that empties a table without logging each row  SQL Server prevents you from truncating a table with foreign keys referencing it  because of the need to check the foreign keys on each row   Truncate is normally ultra-fast  ideal for cleaning out data from a temporary table  It does preserve the structure of the table for future use   If you actually want to remove the table definitions as well as the data  simply drop the tables   See this MSDN article for more info

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I think you means the difference between DELETE TABLE and TRUNCATE TABLE   DROP TABLE      remove the table from the database    DELETE TABLE      without a condition delete all rows  If there are trigger and references then this will process for every row  Also a index will be modify if there one    TRUNCATE TABLE      set the row count zero and without logging each row  That it is many faster as the other both

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None of these answer point out an important difference about these two operations   Drop table is an operation that can be rolled back   However  truncate cannot be rolled back   TRUNCATE TABLE  can be rolled back as well    In this way dropping a very large table can be very expensive if there are many rows  because they all have to be recorded in a temporary space in case you decide to roll it back   Usually  if I want to get rid of a large table  I will truncate it  then drop it   This way the data will be nixed without record  and the table can be dropped  and that drop will be very inexpensive because no data needs to be recorded   It is important to point out though that truncate just deletes data  leaving the table  while drop will  in fact  delete the data and the table itself    assuming foreign keys don t preclude such an action

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truncate removes all the rows  but not the table itself  it is essentially equivalent to deleting with no where clause  but usually faster

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The answers here match up to the question  but I m going to answer the question you didn t ask   Should I use truncate or delete   If you are removing all rows from a table  you ll typically want to truncate  since it s much much faster   Why is it much faster   At least in the case of Oracle  it resets the high water mark   This is basically a dereferencing of the data and allows the db to reuse it for something else

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DELETE  VS TRUNCATE   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 We can use WHERE clause in DELETE but in TRUNCATE you cannot use it When the DELETE statement is executed using a row lock  each row in the table is locked  for deletion  TRUNCATE TABLE always locks the table and page but not each row After a DELETE statement is executed  the table can still contain empty pages If the  delete operation does not use a table lock  the table  heap  will contain many empty  pages  For indexes  the delete operation can leave empty pages behind  although these pages will be deallocated quickly by a background cleanup process TRUNCATE TABLE removes all rows from a table  but the table structure and its columns   constraints  indexes  and so on remain DELETE statement doesn t RESEED identity column but TRUNCATE statement RESEEDS the  IDENTITY column You cannot use TRUNCATE TABLE on tables that     Are referenced by a FOREIGN KEY constraint   You can truncate a table that has a  foreign key that references itself   Participate in an indexed view  Are published by using transactional replication or merge replication  TRUNCATE TABLE cannot activate a trigger because the operation does not log individual  row deletions

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TRUNCATE TABLE is functionally   identical to DELETE statement with no   WHERE clause  both remove all rows in   the table  But TRUNCATE TABLE is   faster and uses fewer system and   transaction log resources than DELETE       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 s data  and only the   page deallocations are recorded in the   transaction log       TRUNCATE TABLE removes all rows from a   table  but the table structure and its   columns  constraints  indexes and so   on remain  The counter used by an   identity for new rows is reset to the   seed for the column  If you want to   retain the identity counter  use   DELETE instead  If you want to remove   table definition and its data  use the   DROP TABLE statement       You cannot use TRUNCATE TABLE on a   table referenced by a FOREIGN KEY   constraint  instead  use DELETE   statement without a WHERE clause    Because TRUNCATE TABLE is not logged    it cannot activate a trigger       TRUNCATE TABLE may not be used on   tables participating in an indexed   view    From http   msdn microsoft com en-us library aa260621 SQL 80  aspx

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DROP and TRUNC do different things   TRUNCATE TABLE     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    DROP TABLE     Removes one or more table definitions   and all data  indexes  triggers    constraints  and permission   specifications for those tables    As far as speed is concerned the difference should be small  And anyway if you don t need the table structure at all  certainly use DROP

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Delete Statement Delete Statement delete table rows and return the number of rows is deleted from the table in this statement  we use where clause to deleted data from the table  Delete Statement is slower than Truncate statement because it deleted records one by one  Truncate Statement Truncate statement Deleted or removing all the rows from the table   It is faster than the Delete Statement because it deleted all the records from the table Truncate statement not return the no of rows are deleted from the table  Drop statement Drop statement deleted all records as well as the structure of the table

User · Answer

DELETE

The DELETE command is used to remove rows from a table. A WHERE clause can be used to only remove some rows. If no WHERE condition is specified, all rows will be removed. After performing a DELETE operation you need to COMMIT or ROLLBACK the transaction to make the change permanent or to undo it.

TRUNCATE

TRUNCATE removes all rows from a table. The operation cannot be rolled back ... As such, TRUCATE is faster and doesn't use as much undo space as a DELETE.

From: http://www.orafaq.com/faq/difference_between_truncate_delete_and_drop_commands

User · Answer

DELETE TableA instead of TRUNCATE TableA   A common misconception is that they do the same thing   Not so   In fact  there are many differences between the two   DELETE is a logged operation on a per row basis   This means that the deletion of each row gets logged and physically deleted   You can DELETE any row that will not violate a constraint  while leaving the foreign key or any other contraint in place   TRUNCATE is also a logged operation  but in a different way   TRUNCATE logs the deallocation of the data pages in which the data exists   The deallocation of data pages means that your data rows still actually exist in the data pages  but the extents have been marked as empty for reuse   This is what makes TRUNCATE a faster operation to perform over DELETE   You cannot TRUNCATE a table that has any foreign key constraints   You will have to remove the contraints  TRUNCATE the table  and reapply the contraints   TRUNCATE will reset any identity columns to the default seed value

[sql] Difference between drop table and truncate table?

DELETE

TRUNCATE

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