Better parsing of USE queries sent with COM_QUERY #4598

[renecannao]

Closes #4598

USE queries sent via COM_QUERY are not processed in a better way, improving their parsing:

• it is implemented into SetParser (even if it is not a SET statement !! , to minimize code changes)
• comments are removed
• it handles schemaname with and without backtick
• in case backtick is used, a space between USE and dbname is optional

This new parser passes the tests in existing reg_test_3493-USE_with_comment-t TAP test, and it also introduced a new set of tests that are automatically executed in debug build.

[renecannao]

Some of the test in reg_test_3493-USE_with_comment-t are failing.

List of all tests: https://github.com/sysown/proxysql/blob/v2.6.3/test/tap/tests/reg_test_3493-USE_with_comment-t.cpp#L171-L185
For reference:

... ("test_use_comment", "/*+ placeholder_comment */ USE test_use_comment", false));
... ("`test_use_comment-a1`", "USE /*+ placeholder_comment */ `test_use_comment-a1`", true));
... ("test_use_comment_1", "  USE /*+ placeholder_comment */   `test_use_comment_1`", false));
... ("test_use_comment_2", "USE/*+ placeholder_comment */ `test_use_comment_2`", false));
... ("test_use_comment_3", "USE /*+ placeholder_comment */`test_use_comment_3`", true));
... ("test_use_comment_4", "  USE /*+ placeholder_comment */   test_use_comment_4", false));
... ("test_use_comment_5", "USE/*+ placeholder_comment */ test_use_comment_5", false));
... ("test_use_comment_6", "USE /*+ placeholder_comment */test_use_comment_6", true));
... ("`test_use_comment-1`", "  USE /*+ placeholder_comment */   `test_use_comment-1`", false));
... ("`test_use_comment-2`", "USE/*+ placeholder_comment */ `test_use_comment-2`", false));
... ("`test_use_comment-3`", "USE /*+ placeholder_comment */`test_use_comment-3`", true));
... ("`test_use_comment-4`", "/*+ placeholder_comment */USE          `test_use_comment-4`", false));
... ("`test_use_comment-5`", "USE/*+ placeholder_comment */`test_use_comment-5`", false));
... ("`test_use_comment-6`", "/* comment */USE`test_use_comment-6`", false));
... ("`test_use_comment-7`", "USE`test_use_comment-7`", false));

[mirostauder]

retest this please

[TomaszKorwel]

This seems to have introduced problem with laravel's doctrine:

[2024-08-29 08:52:28] developmnet.ERROR: SQLSTATE[42000]: Syntax error or access violation: 1148 Unable to parse: use app; (Connection: mysql, SQL: ....) {"exception":"[object] (Illuminate\Database\QueryException(code: 42000): SQLSTATE[42000]: Syntax error or access violation: 1148 Unable to parse: use app; (Connection: mysql, SQL: ... ) at /var/share/nginx/html/current/vendor/laravel/framework/src/Illuminate/Database/Connection.php:829)"

Reverting proxysql to 2.6.3 solved our problem.

Laravel config:

    'connections' => [

        'mysql' => [
            'driver'      => 'mysql',
            'host'        => env('DB_HOST',''),
            'port'        => env('DB_PORT',''),
            'database'    => env('DB_DATABASE', 'app'),
            'username'    => env('DB_USERNAME',''),
            'password'    => env('DB_PASSWORD',''),
            'unix_socket' => env('DB_SOCKET', ''),
            'charset'     => 'latin1',
            'collation'   => 'latin1_swedish_ci',
            'prefix'      => '',
            'strict'      => true,
            'engine'      => null,
        ],

[renecannao]

@TomaszKorwel , yes, we are aware.
Laravel seems to do 2 unusual things at the same time:

• it uses COM_QUERY to send USE command instead of using COM_INIT_DB
• it adds a semicolon at the end of the database name

On our end, we missed removing the semicolon from queries sent by application like Laraval .
PR #4629 fixed this.
Expect 2.6.5 to be released within hours.

[TomaszKorwel]

Thanks!