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---
====== Data Operation - Drop ======


===== About =====
''drop'' is a [[:docs:flow:intermediate|intermediate operation]] that will drop the [[:docs:flow:input|inputs]]. It will remove:
  * their [[:docs:resource:metadata|metadata]]
  * and their [[docs:resource:content|data (content)]].



<note important>
As there is no way to retrieve the data or metadata, you should use this operation with care.
</note>

===== System Equivalence =====

  * A ''drop'' operation on a [[docs:resource:file|file]] is equivalent to a ''remove'' or ''delete''.
  * A ''drop'' operation on a [[docs:resource:sql_table|sql table]] is equivalent to a ''drop table''.



===== Arguments =====

^ Name ^ Default ^ Description ^
| ''force'' | ''false'' | Drop the foreign keys for a table |
| ''cascade'' | ''false'' | Drop recursively the [[:docs:resource:dependency|dependent resources]] |
| ''processing-type'' | ''batch'' | The [[:docs:flow:processing-type|processing type]] \\ In ''stream'' processing, inputs are dropped one at a time \\ In ''batch'' processing, they are dropped in batch |


==== processing-type ====

By default, the [[:docs:flow:processing-type|processing type]] is ''batch'' because it can handle a bad [[docs:resource:sql_view|sql view]].

When ordering the resources in a ''drop'' order, an error may occur if a [[docs:resource:sql_view|sql view]] has a non-valid SQL Statement:
  * the view is not valid anymore
  * we can't get its [[:docs:resource:dependency|dependencies]].

''batch'' processing will ignore it and try to drop the [[:docs:flow:input|inputs]] in received order.
===== Cli =====

The ''drop'' operation is available in the [[:docs:tabul:data:drop|tabul data drop]] cli command


===== Note =====

==== How to drop dependent table ? ====

If you execute drop in:
  * [[:docs:flow:processing-type|batch processing]], the ''drop'' operation will drop them in ''drop'' order automatically.
  * [[:docs:flow:processing-type|stream processing]], the [[:docs:op:select|select operation]] should have the ''order'' option set to ''drop'' so that the tables are send in the pipeline in a ''drop'' order.



Otherwise you may see error like:
```
Cause: ERROR: cannot drop table call_center because other objects depend on it
  Detail: constraint catalog_sales_cs_call_center_sk_fkey on table catalog_sales depends on table call_center
constraint catalog_returns_cr_call_center_sk_fkey on table catalog_returns depends on table call_center
  Hint: Use DROP ... CASCADE to drop the dependent objects too.
```