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Grant & revoke access

Grant or revoke access to table writes using SQL statements.

Tableland allows for some SQL-based access control, along with smart contracts controllers. Developers can provision access to certain addresses using the GRANT or REVOKE keywords, which defines high-level write permissions. Only the owner can write this access control query.

Usage​

To grant permissions for all table mutation abilities, you can make a write query that follows the general format below. Namely, you set the rules for INSERT, UPDATE, or DELETE permissions on a specific table to a specific on-chain address. Keep in mind the 0x address should be treated as a TEXT value and wrapped in single quotes, and the examples below show 0xYOUR_EVM_ADDRESS but be sure to update this accordingly with the correct EVM address.

GRANT
  INSERT,
  UPDATE,
  DELETE
ON my_table
TO '0xYOUR_EVM_ADDRESS'

The primary difference between the keywords is the following:

  • GRANT: Allows the caller to grant an address permissions on a table.
  • REVOKE: Removes any of the privileges that were enabled for an address by way of GRANT.
note

At this time, the most robust features are only available at the smart contract level.

Example statements​

To GRANT permissions for all table mutation abilities, you can execute a query that defines all write possibilities to an address.

GRANT
  INSERT,
  UPDATE,
  DELETE
ON
  my_table
TO
  '0xYOUR_EVM_ADDRESS';

Perhaps at a point in the future, you decide to REVOKE the permission to DELETE rows via another access control write query:

REVOKE
  DELETE
ON
  my_table
FROM
  '0xYOUR_EVM_ADDRESS';
tip

For more information on GRANT and REVOKE, see the SQL specification.

Precedence​

At a lower level, it's possible to set a custom controller using a smart contract. Once a smart contract controller has been configured for a table, it takes precedence over any GRANT or REVOKE statements. If that smart contract controller is ever removed and set back to its initial value ("unsetting" to the 0x0 address), the GRANT and REVOKE statements go back into effect. Again, what's described here with controllers and setting/unsetting is only possible at the smart contract level and does not happen with pure SQL.