OK_Packet

OK_Packet is sent by the server to the client and indicates a successful completion of a command sent by the client before.

Direction

Server to client.

Fields

• int<1> 0x00 : OK_Packet header or (0xFE if CLIENT_DEPRECATE_EOF is set).

• int affected rows.

• int last insert id.

• int<2> server status.

• int<2> warning count.

• If packet has more data:

  • string info.

  • If (status flags & SERVER_SESSION_STATE_CHANGED) and session_tracking_supported (see CLIENT_SESSION_TRACK):

    • string session state info.

The length-encoded info string is not always included in the packet. Check the length of the packet to detect if there is data after the warning count. For the first OK_Packet in the connection it contains (if present) the SSL certificate verification signature. For the following OK_Packets it contains (if present) various human-readable information.

Server status flag

Values of server status flags:

Flag	Value	Details
SERVER_STATUS_IN_TRANS	1	A transaction is currently active.
SERVER_STATUS_AUTOCOMMIT	2	Autocommit mode is set.
SERVER_MORE_RESULTS_EXISTS	8	More results exists (more packets will follow).
SERVER_QUERY_NO_GOOD_INDEX_USED	16	Set if EXPLAIN would've shown Range checked for each record.
SERVER_QUERY_NO_INDEX_USED	32	The query did not use an index.
SERVER_STATUS_CURSOR_EXISTS	64	When using COM_STMT_FETCH, indicate that current cursor still has result.
SERVER_STATUS_LAST_ROW_SENT	128	When using COM_STMT_FETCH, indicate that current cursor has finished to send results.
SERVER_STATUS_DB_DROPPED	1<<8	Database has been dropped.
SERVER_STATUS_NO_BACKSLASH_ESCAPES	1<<9	Current escape mode is "no backslash escape".
SERVER_STATUS_METADATA_CHANGED	1<<10	A DDL change did have an impact on an existing PREPARE (an automatic re-prepare has been executed).
SERVER_QUERY_WAS_SLOW	1<<11	The query was slower than long_query_time.
SERVER_PS_OUT_PARAMS	1<<12	This result set contains stored procedure output parameter.
SERVER_STATUS_IN_TRANS_READONLY	1<<13	Current transaction is a read-only transaction.
SERVER_SESSION_STATE_CHANGED	1<<14	Session state change. See session change type for more information.

Session state info

• While packet has remaining data:

  • int<1> session change type.

  • If (session-change-type != SESSION_TRACK_STATE_CHANGE):

    • int total length.

  • string session data change.

Session change type

Change Type	Flag
0	SESSION_TRACK_SYSTEM_VARIABLES
1	SESSION_TRACK_SCHEMA
2	SESSION_TRACK_STATE_CHANGE
3	SESSION_TRACK_GTIDS
4	SESSION_TRACK_TRANSACTION_CHARACTERISTICS
5	SESSION_TRACK_TRANSACTION_STATE

Session Data Change

Each type of data has its own kind of format:

SESSION_TRACK_SCHEMA

• string new current schema.

SESSION_TRACK_SYSTEM_VARIABLES

While there is remaining data:

• string variable data.

For each variable data:

• string variable name.

• string variable value.

Possible tracked variables list is tracked by session_track_system_variables special variable value description:

• redirect_url: format is mariadb/mysql:[<user>[:<password>]@]<host>[:<port>]/[<db>[?<opt1>=<value1>[&<opt2>=<value2>]]]. Possible options:

  • ttl : cache timeout in ms to remember redirection, in order to reconnect directly to new host. 0=no caching

SESSION_TRACK_STATE_CHANGE

Indicates if session state changes occurred. The value is represented as 1.

• string 1 if session state tracking was enabled.

SESSION_TRACK_GTIDS

This tracker is not implemented by MariaDB.

SESSION_TRACK_TRANSACTION_CHARACTERISTICS

• string Transaction characteristics.

Transaction characteristics is the set of SQL statements that reproduce the type and state of the current transaction. It can consist of the following SQL statements:

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
SET TRANSACTION ISOLATION LEVEL READ COMMITTED;
SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
START TRANSACTION;
START TRANSACTION WITH CONSISTENT SNAPSHOT;
START TRANSACTION WITH CONSISTENT SNAPSHOT, READ ONLY;
START TRANSACTION WITH CONSISTENT SNAPSHOT, READ WRITE;
SET TRANSACTION READ ONLY;
SET TRANSACTION READ WRITE;
XA START <XA specification>;

SESSION_TRACK_TRANSACTION_STATE

• string Transaction state string.

The transaction state string is always 8 characters long. The characters, in order, are:

1. No transaction: _ Explicit transaction: T Implicit transaction: I

2. Transaction read safe: _ Transaction read unsafe: r

3. Unknown transaction type: _ Read-only transaction: R

4. Transaction write safe: _ Transaction write unsafe: w

5. Unknown transaction type: _ Read-write transaction: W

6. Transaction statement safe: _ Transaction statement unsafe: s

7. Transaction does not have resultsets: _ Transaction with result sets: S

8. No locked tables: _ Tables have been locked: L

Notes

• To determine if session tracking is enabled, check if the CLIENT_SESSION_TRACK flag is set in server_capabilities.

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