DataBlade API data type structures
Many DataBlade® API functions provide information for DataBlade API modules in special data type structures. The names of these data type structures begin with the MI_ prefix.
The following table lists the data type structures, their purposes, and where you can find detailed descriptions of them.
| DataBlade API data type structure | Purpose | More information |
|---|---|---|
| MI_COLL_DESC | Collection descriptor, which describes the structure of a collection | A collection descriptor |
| MI_COLLECTION | Collection structure, which contains the elements of a collection | A collection structure |
| MI_CONNECTION | Connection descriptor, which contains the execution context for a connection | Establish a connection |
| MI_CONNECTION_INFO | Connection-information descriptor, which contains connection parameters for an open connection | Connection parameters |
| MI_DATABASE_INFO | Database-information descriptor, which contains database parameters for an open connection | Database parameters |
| MI_DATUM | Datum, which provides a transport mechanism to pass data of an SQL data type by value or by reference | The MI_DATUM data type |
| MI_ERROR_DESC | Error descriptor, which describes an exception | Event information |
| MI_FPARAM | Function-parameter structure, which holds information about a UDR that the routine can access during its execution | Access MI_FPARAM routine-state information |
| MI_FUNCARG | Function-argument structure, which holds information about the argument of a companion UDR | The MI_FUNCARG data type |
| MI_FUNC_DESC | Function descriptor, which describes a UDR that is to be invoked with the Fastpath interface | Obtain a function descriptor |
| MI_LO_FD | LO file descriptor, which describes an open smart large object | Obtain an LO file descriptor |
| MI_LO_HANDLE | LO handle, which identifies the location of a smart large object in its sbspace | Obtain an LO handle |
| MI_LO_SPEC | LO-specification structure, which contains storage characteristics for a smart large object | Obtain the LO-specification structure |
| MI_LO_STAT | LO-status structure, which contains status information for a smart large object | Obtaining status information for a smart large object |
| MI_PARAMETER_INFO | Parameter-information descriptor, which specifies whether callbacks are enabled or disabled and whether pointers are checked in client LIBMI applications | Session parameters |
| MI_ROW | Row (or row structure), which contains either the column values of a table row or field values of a row type | Retrieve rows A row structure |
| MI_ROW_DESC | Row descriptor, which describes the structure of a row | Obtain row information A row descriptor |
| MI_SAVE_SET | Save-set descriptor, which describes a save set | Create a save set |
| MI_STATEMENT | Statement descriptor, which describes a prepared SQL statement | Execute prepared SQL statements |
| mi_statret | Statistics-return structure (C language structure), which holds the collected statistics for a user-defined data type | SET_END in statcollect() |
| MI_STREAM | Stream descriptor, which describes an open stream A
stream is an object that can be written to or read from. The DataBlade
API has
functions for the following predefined stream classes:
|
|
| MI_TRANSITION_DESC | Transition descriptor, which describes a state transition | Understanding state-transition events |
| MI_TYPEID | Type identifier, which uniquely identifies a data type within a database | Type identifiers |
| MI_TYPE_DESC | Type descriptor, which provides information about a data type | Type descriptors |
The DataBlade
API provides
constructor and destructor functions for most of these public data
type structures. These functions handle memory allocation of these
data type structures, as follows:
- The constructor function for a DataBlade
API data
type structure creates a new instance of the data type structure.
A constructor function usually returns a pointer to the DataBlade API data type structure and allocates memory for the structure.
Server only: The memory allocation is in the current memory duration, which is PER_ROUTINE by default. For more information, see Choose the memory duration. - The destructor function for a DataBlade
API data
type structure frees the instance of the data type structure.
You specify a pointer to the DataBlade API data type structure to the destructor function. The destructor function deallocates memory for the specified data type structure. Call destructor functions only for DataBlade API data type structures that you explicitly allocated with the corresponding constructor function.