Method writeCommandLongData

packets.go:998–1041

https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_stmt_send_long_data.html

(paramID int, arg []byte)

// https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_stmt_send_long_data.html
func (stmt *mysqlStmt) writeCommandLongData(paramID int, arg []byte) error {
	maxLen := stmt.mc.maxAllowedPacket - 1
	pktLen := maxLen

	// After the header (bytes 0-3) follows before the data:
	// 1 byte command
	// 4 bytes stmtID
	// 2 bytes paramID
	const dataOffset = 1 + 4 + 2

	// Cannot use the write buffer since
	// a) the buffer is too small
	// b) it is in use
	data := make([]byte, 4+1+4+2+len(arg))

	copy(data[4+dataOffset:], arg)

	for argLen := len(arg); argLen > 0; argLen -= pktLen - dataOffset {
		if dataOffset+argLen < maxLen {
			pktLen = dataOffset + argLen
		}

		// Add command byte [1 byte]
		data[4] = comStmtSendLongData

		// Add stmtID [32 bit]
		binary.LittleEndian.PutUint32(data[5:], stmt.id)

		// Add paramID [16 bit]
		binary.LittleEndian.PutUint16(data[9:], uint16(paramID))

		// Send CMD packet
		err := stmt.mc.writePacket(data[:4+pktLen])
		// Every COM_LONG_DATA packet reset Packet Sequence
		stmt.mc.resetSequence()
		if err == nil {
			data = data[pktLen-dataOffset:]
			continue
		}
		return err
	}

	return nil
}

// Execute Prepared Statement
// https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_com_stmt_execute.html