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.