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Temporal table security

  • Artikkeli

Applies to: SQL Server 2016 (13.x) and later Azure SQL Database Azure SQL Managed Instance

To understand security as it applies to temporal tables, you must understand the security principles that apply to temporal tables. After you understand these security principles, you're ready to dive into the security around the CREATE TABLE, ALTER TABLE, and SELECT statements.

Security principles

The following table describes the security principles that apply to temporal tables:

Principle Description
Enable/disable system-versioning requires highest privileges on affected objects Enabling and disabling SYSTEM_VERSIONING requires CONTROL permission on both the current and the history table.
History data can't be modified directly When SYSTEM_VERSIONING is ON, users can't alter history data, regardless of their actual permissions on the current or history table. This limitation includes both data and schema modifications. 1
Querying history data requires SELECT permission on the history table A user with SELECT permission on the current table doesn't automatically have SELECT permission on the history table.
Audit reveals operations affecting history table in specific ways Auditing settings from the current table aren't automatically applied to the history table. Auditing needs to be enabled explicitly for history table. Once enabled, auditing on the history table regularly captures all direct attempts to access the data (regardless if they were successful or not).

SELECT with temporal query extension shows that the history table was affected with that operation.

CREATE/ALTER temporal table exposes information that the permission check happens on the history table as well. The audit file contains additional records for the history table.

DML operations on the current table reveal that history table was affected, but additional_information provides necessary context (DML was result of SYSTEM_VERSIONING).

1 If you have ALTER permission on the current table and the history table, and you drop a column in the current table, the associated column in the history table is also dropped, even if SYSTEM_VERSIONING is ON.

Perform schema operations

When SYSTEM_VERSIONING is set to ON, schema modification operations are limited.

Disallowed ALTER schema operations

Operation Current table History table
DROP TABLE Disallowed Disallowed
ALTER TABLE...SWITCH PARTITION SWITCH IN only (see Partition with temporal tables) SWITCH OUT only (see Partition with temporal tables)
ALTER TABLE...DROP PERIOD Disallowed N/A
ALTER TABLE...ADD PERIOD N/A Disallowed

Allowed ALTER TABLE operations

Operation Current History
ALTER TABLE...REBUILD Allowed (independently) Allowed (independently)
CREATE INDEX Allowed (independently) Allowed (independently)
CREATE STATISTICS Allowed (independently) Allowed (independently)

Security of the CREATE temporal table statement

Feature Create new history table Reuse existing history table
Permission required CREATE TABLE permission in the database

ALTER permission on the schemas into which the current and history tables are being created		 CREATE TABLE permission in the database

ALTER permission on the schema in which the current table will be created.

CONTROL permission on the history table specified as part of the CREATE TABLE statement creating the temporal table.
Audit Audit shows that users attempted to create two objects. Operation might fail due to lack of permissions to create a table in the database, or due to lack of permissions to alter schemas for either table. Audit shows that the temporal table was created. The operation might fail due to lack of permission to create a table in the database, lack of permissions to alter the schema for the temporal table, or lack of permissions on the history table.

Security of the ALTER temporal table SET (SYSTEM_VERSIONING ON/OFF) statement

Feature Create new history table Reuse existing history table
Permission required CONTROL permission in the database.

CREATE TABLE permission in the database.

ALTER permission on the schemas into which the history table is being created.		 CONTROL permission on the original table that is altered.

CONTROL permission on the history table specified as part of the ALTER TABLE statement.
Audit Audit shows that the temporal table was altered and the history table was created at the same time. This operation might fail due to lack of permissions to create a table in the database, lack of permissions to alter schema for history table, or lack of permission to modify the temporal table. Audit shows that the temporal table was altered, but the operation required access to the history table. The operation might fail due to lack of permissions on the history table, or lack of permissions on the current table.

Security of the SELECT statement

SELECT permission is unchanged for SELECT statements that don't affect the history table. For SELECT statements that affect the history table, SELECT permission is required on both the current table and the history table.

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