feature request : MariaDB pipeline PREPARE + EXECUTE

[rusher]

this feature request is part of a serie to improve performance when using MariaDB : see doc

MariaDB (since 10.2) permit sending COM_STMT_PREPARE + COM_STMT_EXECUTE directly, without having to wait for prepare, this permit faster first execution. It wpuld be great to have that !

from https://mariadb.com/kb/en/mariadb-protocol-differences-with-mysql/#pipelining-prepare-execute

Connectors usually follow a two-step process for prepared statements:

Prepare: Send a COM_STMT_PREPARE command to the server, receiving a statement ID in response.
Execute: Send a COM_STMT_EXECUTE command, using the statement ID obtained in the previous step.
When the server support MARIADB_CLIENT_STMT_BULK_OPERATIONS capability (since MariaDB 10.2), a specific statement ID value of -1 (or 0xffffffff in hexadecimal) can be used to indicate that the previously prepared statement could be reused. This enables connectors to pipeline the preparation and execution steps into a single request:

Send a COM_STMT_PREPARE then a COM_STMT_EXECUTE with statement ID -1 (0xffffffff) commands to the server.
Read the prepare and execute responses
If the COM_STMT_PREPARE command returns an error (ERR_Packet), the subsequent COM_STMT_EXECUTE with statement ID -1 will also fail and return an error.

By eliminating the round trip for the separate COM_STMT_EXECUTE command, this approach improves performance for the first execution.

Traditionally, connectors send COM_STMT_PREPARE, wait for results, then execute COM_STMT_EXECUTE with statement_id received from the prepare result.

This description has been done for COM_STMT_EXECUTE, but COM_STMT_BULK_EXECUTE works exactly the same way.