spi_execute_with_args(3) [centos man page]
SPI_EXECUTE_WITH_ARGS(3) PostgreSQL 9.2.7 Documentation SPI_EXECUTE_WITH_ARGS(3) NAME
SPI_execute_with_args - execute a command with out-of-line parameters SYNOPSIS
int SPI_execute_with_args(const char *command, int nargs, Oid *argtypes, Datum *values, const char *nulls, bool read_only, long count) DESCRIPTION
SPI_execute_with_args executes a command that might include references to externally supplied parameters. The command text refers to a parameter as $n, and the call specifies data types and values for each such symbol. read_only and count have the same interpretation as in SPI_execute. The main advantage of this routine compared to SPI_execute is that data values can be inserted into the command without tedious quoting/escaping, and thus with much less risk of SQL-injection attacks. Similar results can be achieved with SPI_prepare followed by SPI_execute_plan; however, when using this function the query plan is always customized to the specific parameter values provided. For one-time query execution, this function should be preferred. If the same command is to be executed with many different parameters, either method might be faster, depending on the cost of re-planning versus the benefit of custom plans. ARGUMENTS
const char * command command string int nargs number of input parameters ($1, $2, etc.) Oid * argtypes an array containing the OIDs of the data types of the parameters Datum * values an array of actual parameter values const char * nulls an array describing which parameters are null If nulls is NULL then SPI_execute_with_args assumes that no parameters are null. bool read_only true for read-only execution long count maximum number of rows to return, or 0 for no limit RETURN VALUE
The return value is the same as for SPI_execute. SPI_processed and SPI_tuptable are set as in SPI_execute if successful. PostgreSQL 9.2.7 2014-02-17 SPI_EXECUTE_WITH_ARGS(3)
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SPI_PREPARE(3) PostgreSQL 9.2.7 Documentation SPI_PREPARE(3) NAME
SPI_prepare - prepare a statement, without executing it yet SYNOPSIS
SPIPlanPtr SPI_prepare(const char * command, int nargs, Oid * argtypes) DESCRIPTION
SPI_prepare creates and returns a prepared statement for the specified command, but doesn't execute the command. The prepared statement can later be executed repeatedly using SPI_execute_plan. When the same or a similar command is to be executed repeatedly, it is generally advantageous to perform parse analysis only once, and might furthermore be advantageous to re-use an execution plan for the command. SPI_prepare converts a command string into a prepared statement that encapsulates the results of parse analysis. The prepared statement also provides a place for caching an execution plan if it is found that generating a custom plan for each execution is not helpful. A prepared command can be generalized by writing parameters ($1, $2, etc.) in place of what would be constants in a normal command. The actual values of the parameters are then specified when SPI_execute_plan is called. This allows the prepared command to be used over a wider range of situations than would be possible without parameters. The statement returned by SPI_prepare can be used only in the current invocation of the procedure, since SPI_finish frees memory allocated for such a statement. But the statement can be saved for longer using the functions SPI_keepplan or SPI_saveplan. ARGUMENTS
const char * command command string int nargs number of input parameters ($1, $2, etc.) Oid * argtypes pointer to an array containing the OIDs of the data types of the parameters RETURN VALUE
SPI_prepare returns a non-null pointer to an SPIPlan, which is an opaque struct representing a prepared statement. On error, NULL will be returned, and SPI_result will be set to one of the same error codes used by SPI_execute, except that it is set to SPI_ERROR_ARGUMENT if command is NULL, or if nargs is less than 0, or if nargs is greater than 0 and argtypes is NULL. NOTES
If no parameters are defined, a generic plan will be created at the first use of SPI_execute_plan, and used for all subsequent executions as well. If there are parameters, the first few uses of SPI_execute_plan will generate custom plans that are specific to the supplied parameter values. After enough uses of the same prepared statement, SPI_execute_plan will build a generic plan, and if that is not too much more expensive than the custom plans, it will start using the generic plan instead of re-planning each time. If this default behavior is unsuitable, you can alter it by passing the CURSOR_OPT_GENERIC_PLAN or CURSOR_OPT_CUSTOM_PLAN flag to SPI_prepare_cursor, to force use of generic or custom plans respectively. This function should only be called from a connected procedure. SPIPlanPtr is declared as a pointer to an opaque struct type in spi.h. It is unwise to try to access its contents directly, as that makes your code much more likely to break in future revisions of PostgreSQL. The name SPIPlanPtr is somewhat historical, since the data structure no longer necessarily contains an execution plan. PostgreSQL 9.2.7 2014-02-17 SPI_PREPARE(3)