Table Variable vs. Temp Table Summary:Local Temporary Tables and Table Variables
| Feature | Table Variable | Temp Table | Note |
| Table Name | Max 128 characters | Max 116 characters | |
| Data Storage | In memory and TempDB | TempDB | |
| Meta Data | In memory | TempDB | A table variable inherits current database settings and can use the registered UDTs, user defined data types, and xml collections in the database. A temp table inherits the settings of TempDB and cannot use the types created in the user database if the same types do not exist in the TempDB. |
| Scope | Current batch | Current session | Temp tables created in a stored procedure (SP) can be referenced by dynamic queries in the SP, sub SPs, triggers fired by the affected tables of the SP. |
| Constraints | Allowed | Allowed | For table variables, since no DDL is allowed, constraints can not be created in separate DDL statements. |
| DDL | Not allowed | Allowed. | E.g. create Index on the temp table. |
| Concurrent | Supported | Supported | Constraints and Indexes with explicit name in a temp table cause duplicate name error. |
| Statistics | Not supported | Supported | Estimated row number in execution plan for table variable is always 1 |
| Parallel execution plan | Supported only for select | Supported | Parallel query execution plans are not generated for queries that modify table variables. |
| Transaction and Locking | Not participated | Participated | Data in table variable is not affected if the transaction is rolled back |
| Cause Recompile | No | Yes | Temp Table creation causes SPs/batches to recompile |
| SELECT INTO <t> | Not supported | Supported | |
| INSERT <t> EXEC | Not supported | Supported | |
| Use | UDFs, Stored procedures, Triggers, Batches | Stored procedures, Triggers, Batches | Temp tables can't be used in UDFs. |