Comparing the collection types

The following table compares the collection types based on the considerations.

Comparing factor	Nested table	Varray	Associative array
Maximum size	Unbound and grows dynamically.	Bounded. However, varray size, can only be increased thereafter.	Unbound and grows dynamically.
Sparsity	Starts dense but may become sparse due to deletions.	Always dense.	Can be sparse.
Storage considerations	Out-of-line storage in a separate storage table.	In-line storage up to 4000 bytes. For out-of-line storage, the LOB clause must be specified.	Non-persistent collection uses program memory that is UGA.
Querying ability	A nested table type column can be queried as an instance. However, unnesting of an instance is possible using the TABLE or CAST clause.	A varray type column can be queried as an instance. However, unnesting of an instance is possible using the TABLE or CAST clause.	Non-persistent collection.
DML operations	Piecewise and atomic operations possible...