What happens to index when table is dropped in Oracle?

What happens to index when table is dropped in Oracle?

Dropping a table removes the table definition from the data dictionary. All indexes and triggers associated with a table are dropped. All views and PL/SQL program units dependent on a dropped table remain, yet become invalid (not usable).

How do you drop an index from a table in Oracle?

The syntax for dropping an index in Oracle/PLSQL is: DROP INDEX index_name; index_name. The name of the index to drop.

Can we drop index in Oracle?

Use the DROP INDEX statement to remove an index or domain index from the database. When you drop an index, Oracle Database invalidates all objects that depend on the underlying table, including views, packages, package bodies, functions, and procedures.

What does the database let you do if you require more explicit control over the indexes associated with unique and primary key constraints?

If you require more explicit control over the indexes associated with UNIQUE and PRIMARY KEY constraints, the database lets you:

1. Specify an existing index that the database is to use to enforce the constraint.
2. Specify a CREATE INDEX statement that the database is to use to create the index and enforce the constraint.

Does drop table free up space?

Dropping a table will free up the space within the database, but will not release the space back to Windows. That requires shrinking the database file.

Does drop table also drop index?

DROP TABLE removes tables from the database. DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified.

How do I drop a table in Oracle?

Oracle DROP TABLE

1. First, indicate the table and its schema that you want to drop after the DROP TABLE clause.
2. Second, specify CASCADE CONSTRAINTS clause to remove all referential integrity constraints which refer to primary and unique keys in the table.

Does Oracle rebuild indexes automatically?

The indexes are updated with the base table operation. You are not required to update later and independently rebuild the indexes. The global indexes are more highly available, because they are not marked UNUSABLE .

Which is faster TRUNCATE or DROP?

TRUNCATE is a DDL(Data Definition Language) command. It is used to delete all the tuples from the table. The TRUNCATE command is faster than both the DROP and the DELETE command. Like the DROP command we also can’t rollback the data after using the this command.

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 .

What is index and different types of indexes in Oracle?

Oracle uses two different index architectures: b-Tree indexes and bitmap indexes. Cluster indexes, bitmap join indexes, function-based indexes, reverse key indexes and text indexes are all just variations on the two main types.

What is drop Index in SQL?

In SQL Server DROP INDEX Removes one or more relational, spatial, filtered, or XML indexes from the current database. You can drop a clustered index and move the resulting table to another filegroup or partition scheme in a single transaction by specifying the MOVE TO option.

What is DROP INDEX?

When you drop an index, Oracle Database invalidates all objects that depend on the underlying table, including views, packages, package bodies, functions, and procedures. When you drop a global partitioned index, a range-partitioned index, or a hash-partitioned index, all the index partitions are also dropped.