GdaVconnectionDataModelFunc ()

void
(*GdaVconnectionDataModelFunc) (GdaDataModel *Param1,
                                const gchar *Param2,
                                gpointer Param3);

This function is called for every GdaDataModel representing a table in a GdaVconnectionDataModel connection, when using the gda_vconnection_data_model_foreach() method.

GdaVconnectionDataModelCreateColumnsFunc ()

GList *
(*GdaVconnectionDataModelCreateColumnsFunc)
                               (GdaVconnectionDataModelSpec *Param1,
                                GError **Param2);

Function called to create the virtual table's columns, as GdaColumn objects.

GdaVconnectionDataModelCreateModelFunc ()

GdaDataModel *
(*GdaVconnectionDataModelCreateModelFunc)
                               (GdaVconnectionDataModelSpec *Param1);

Function called to create a GdaDataModel object, called when a virtual table's data need to be accessed, and when optimization is not handled.

GdaVconnectionDataModelParseFilterFunc ()

void
(*GdaVconnectionDataModelParseFilterFunc)
                               (GdaVconnectionDataModelSpec *Param1,
                                GdaVconnectionDataModelFilter *Param2);

This function actually analyses the proposed optimization and modified Param2 to tell the database engine how (if applicable) it implements the optimization.

GdaVconnectionDataModelCreateFModelFunc ()

GdaDataModel *
(*GdaVconnectionDataModelCreateFModelFunc)
                               (GdaVconnectionDataModelSpec *Param1,
                                int Param2,
                                const char *Param3,
                                int Param4,
                                GValue **Param5);

Function called to create a GdaDataModel object, called when a virtual table's data need to be accessed, and when optimization is handled.

gda_vconnection_data_model_add ()

gboolean
gda_vconnection_data_model_add (GdaVconnectionDataModel *cnc,
                                GdaVconnectionDataModelSpec *spec,
                                GDestroyNotify spec_free_func,
                                const gchar *table_name,
                                GError **error);

Create a new virtual table named table_name in cnc . The contents of that new table is dictated by what's in spec .

If there is just one GdaDataModel to make appear as a table then the gda_vconnection_data_model_add_model() method is easier to use.

The spec_free_func can (depending on your code) be used to clean memory allocated for spec or spec->data_model .

If an error occurs, then the spec_free_func function is called using spec as argument.

gda_vconnection_data_model_add_model ()

gboolean
gda_vconnection_data_model_add_model (GdaVconnectionDataModel *cnc,
                                      GdaDataModel *model,
                                      const gchar *table_name,
                                      GError **error);

Make model appear as a table named table_name in the cnc connection (as if a "CREATE TABLE..." statement was executed, except that the data contained within model is actually used when table_name 's contents is read or written).

For a more general approach, see the gda_vconnection_data_model_add() method.

gda_vconnection_data_model_remove ()

gboolean
gda_vconnection_data_model_remove (GdaVconnectionDataModel *cnc,
                                   const gchar *table_name,
                                   GError **error);

Remove the table named table_name in the cnc connection (as if a "DROP TABLE..." statement was executed, except that no data gets destroyed as the associated data model remains the same).

gda_vconnection_data_model_get_table_name ()

const gchar *
gda_vconnection_data_model_get_table_name
                               (GdaVconnectionDataModel *cnc,
                                GdaDataModel *model);

Find the name of the table associated to model in cnc

gda_vconnection_data_model_get_model ()

GdaDataModel *
gda_vconnection_data_model_get_model (GdaVconnectionDataModel *cnc,
                                      const gchar *table_name);

Find the GdaDataModel object representing the table_name table in cnc . it can return NULL either if no table named table_name exists, or if that table actually exists but no GdaDataModel has yet been created. For a more general approach, use the gda_vconnection_data_model_get().

gda_vconnection_data_model_get ()

GdaVconnectionDataModelSpec *
gda_vconnection_data_model_get (GdaVconnectionDataModel *cnc,
                                const gchar *table_name);

Find the GdaVconnectionDataModelSpec specifying how the table named table_name is represented in cnc .

Since: 4.2.6

gda_vconnection_data_model_foreach ()

void
gda_vconnection_data_model_foreach (GdaVconnectionDataModel *cnc,
                                    GdaVconnectionDataModelFunc func,
                                    gpointer data);

Call func for each table in cnc .

Warning: func will be called for any table present in cnc even if no data model represents the contents of the table (which means the 1st argument of func may be NULL)

struct GdaVconnectionDataModel

struct GdaVconnectionDataModel;

struct GdaVconnectionDataModelSpec

struct GdaVconnectionDataModelSpec {
	GdaDataModel                             *data_model;
	GdaVconnectionDataModelCreateColumnsFunc  create_columns_func;
	GdaVconnectionDataModelCreateModelFunc    create_model_func;

	GdaVconnectionDataModelParseFilterFunc    create_filter_func;
	GdaVconnectionDataModelCreateFModelFunc   create_filtered_model_func;
};

This structure holds all the information supplied to declare a virtual table using gda_vconnection_data_model_add(). You don't need to provider pointers for all the functions and for data_model , but the following rules have to be respected:

Note that if specifying a create_filtered_model_func , you should also specifiy a create_filter_func function which is actually responsible for analysing the optimization.

struct GdaVconnectionDataModelFilter

struct GdaVconnectionDataModelFilter {
	/* Inputs */
	int nConstraint; /* Number of entries in aConstraint */
	struct GdaVirtualConstraint {
		int iColumn;       /* Column on left-hand side of constraint */
		GdaSqlOperatorType op;  /* Constraint operator, among _EQ, _LT, _LEQ, _GT, _GEQ, _REGEXP */
	} *aConstraint;            /* Table of WHERE clause constraints */
	int nOrderBy;              /* Number of terms in the ORDER BY clause */
	struct GdaVirtualOrderby {
		int iColumn;       /* Column number */
		gboolean desc;     /* TRUE for DESC.  FALSE for ASC. */
	} *aOrderBy;               /* The ORDER BY clause */

	/* Outputs */
	struct GdaVirtualConstraintUsage {
		int argvIndex;     /* if >0, constraint is part of argv to xFilter */
		gboolean omit;     /* Do not code a test for this constraint if TRUE */
	} *aConstraintUsage;
	int idxNum;                /* Number used to identify the index */
	gpointer idxPointer;       /* Pointer used to identify the index */
	gboolean orderByConsumed;  /* TRUE if output is already ordered */
	double estimatedCost;      /* Estimated cost of using this index */
};

This structure contains data which should be analysed to produce a data model (used as data for a virtual table) when a GdaVconnectionDataModelCreateFModelFunc is called. The structure contains an input part (which should not be modified) and and output part (it is closely mapped with SQLite's sqlite3_index_info type).

A pointer to this structure is passed to the GdaVconnectionDataModelParseFilterFunc function and the function has to modify the variables in the output part (marked as *Outputs*).

The idxNum and idxPointer are passed to the GdaVconnectionDataModelCreateFModelFunc function call and they represent nothing specific except that the GdaVconnectionDataModelParseFilterFunc and GdaVconnectionDataModelCreateFModelFunc functions need to agree on their meaning.

See the gda-vconnection-hub.c file for an usage example.

The “vtable-created” signal

void
user_function (GdaVconnectionDataModel *cnc,
               char                    *spec,
               gpointer                 user_data)

Signal emitted when a new virtual table has been declared

Flags: Run Last

The “vtable-dropped” signal

void
user_function (GdaVconnectionDataModel *cnc,
               char                    *spec,
               gpointer                 user_data)

Signal emitted when a new virtual table has been undeclared

Flags: Run Last