Oracle and PostgreSQL Invisible Indexes
Feature compatibility | AWS SCT / AWS DMS automation level | AWS SCT action code index | Key differences |
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PostgreSQL doesn’t support invisible indexes. |
Oracle Usage
In Oracle, the invisible index feature gives database administrators the ability to create indexes, or change existing indexes, that are ignored by the optimizer. They are maintained during DML operations and are kept relevant, but are different from usable indexes.
The most common uses for invisible indexes are:
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Testing the effect of a dropped index without actually dropping it.
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Using a specific index for certain operations or modules of an application without affecting the overall application.
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Adding an index to a set of columns on which an index already exists.
Database administrators can force the optimizer to use invisible indexes by changing the OPTIMIZER_USE_INVISIBLE_INDEXES
parameter to true. You can use invisible indexes if they are specified as a HINT.
Examples
Change an index to an invisible index.
ALTER INDEX idx_name INVISIBLE;
Change an invisible index to a visible index.
ALTER INDEX idx_name VISIBLE;
Create an invisible index.
CREATE INDEX idx_name ON employees(first_name) INVISIBLE;
Query all invisible indexes.
SELECT TABLE_OWNER, INDEX_NAME FROM DBA_INDEXES WHERE VISIBILITY = 'INVISIBLE';
For more information, see Understand When to Use Unusable or Invisible Indexes
PostgreSQL Usage
Currently, Aurora PostgreSQL doesn’t provide a directly comparable alternative for Oracle invisible indexes.