For you to insert rows into a table, the table must be in your own schema or you must have the INSERT object privilege on the table.
For you to insert rows into the base table of a view, the owner of the schema containing the view must have the INSERT object privilege on the base table. Also, if the view is in a schema other than your own, then you must have the INSERT object privilege on the view.
If you have the INSERT ANY TABLE system privilege, then you can also insert rows into any table or the base table of any view.
Conventional and Direct-Path INSERT
You can use the INSERT statement to insert data into a table, partition, or view in two ways: conventional INSERT and direct-path INSERT. When you issue a conventional INSERT statement, Oracle Database reuses free space in the table into which you are inserting and maintains referential integrity constraints. With direct-path INSERT. the database appends the inserted data after existing data in the table. Data is written directly into datafiles, bypassing the
buffer cache. Free space in the existing data is not reused. This alternative enhances performance during insert operations and is similar to the functionality of the Oracle direct-path loader utility, SQL*Loader.
Direct-path INSERT is subject to a number of restrictions. If any of these restrictions is violated, then Oracle Database executes conventional INSERT serially without returning any message, unless otherwise noted:
You can have multiple direct-path INSERT statements in a single transaction, with or without other DML statements. However, after one DML statement alters a particular table, partition, or index, no other DML statement in the transaction can access that table, partition, or index.
Queries that access the same table, partition, or index are allowed before the direct-path INSERT statement, but not after it.
If any serial or parallel statement attempts to access a table that has already been modified by a direct-path INSERT in the same transaction, then the database returns an error and rejects the statement.
The target table cannot be index organized or part of a cluster.
The target table cannot contain object type columns.Source: docs.oracle.com