Since Oracle 12c, Oracle has also offered another feature in this regard: Attribute Clustering . It offers the possibility of influencing the physical organization of the data in a heap table. Attribute Clustering makes it possible to specify how the data should be physically organized for the heap table, which actually has no organization.
How is that supposed to work, since by definition a heap table is called that precisely because there are no specifications as to where data should be stored in it? Attribute clustering in Oracle is therefore only taken into account for certain operations on the heap algeria telegram screening table - namely, whenever new blocks of data are written directly. This is the case, for example, with the aforementioned APPEND mode of the insert, with a CREATE TABLE AS SELECT operation, or with an ALTER TABLE MOVE when the table is reorganized and completely rewritten.
Meanwhile, the database ignores the attribute clustering in conventional DML - so if a normal insert is made into the heap table, the normal rules described above apply - the row is written wherever there is space, regardless of any specifications using attribute clustering as to how the data should be organized.
Therefore, to effectively apply attribute clustering to a heap table, the data must be inserted using APPEND mode or created using a CREATE TABLE AS SELECT operation - this is often the case in data warehouse environments when data is processed in batches as part of ETL transformations or via exchange partition operations.