SPI_exec(query, tcount)
SPI_ERROR_UNCONNECTED if called from an un-connected procedure |
SPI_ERROR_ARGUMENT if query is NULL or tcount < 0. |
SPI_ERROR_UNCONNECTED if procedure is unconnected. |
SPI_ERROR_COPY if COPY TO/FROM stdin. |
SPI_ERROR_CURSOR if DECLARE/CLOSE CURSOR, FETCH. |
SPI_ERROR_TRANSACTION if BEGIN/ABORT/END. |
SPI_ERROR_OPUNKNOWN if type of query is unknown (this shouldn't occur). |
If execution of your query was successful then one of the following (non-negative) values will be returned:
SPI_OK_UTILITY if some utility (e.g. CREATE TABLE ...) was executed |
SPI_OK_SELECT if SELECT (but not SELECT ... INTO!) was executed |
SPI_OK_SELINTO if SELECT ... INTO was executed |
SPI_OK_INSERT if INSERT (or INSERT ... SELECT) was executed |
SPI_OK_DELETE if DELETE was executed |
SPI_OK_UPDATE if UPDATE was executed |
SPI_exec
creates an execution
plan (parser+planner+optimizer) and executes the query for
tcount tuples.
This should only be called from a connected procedure. If tcount is zero then it executes the query for all tuples returned by the query scan. Using tcount > 0 you may restrict the number of tuples for which the query will be executed (much like a LIMIT clause). For example,
SPI_exec ("INSERT INTO tab SELECT * FROM tab", 5);
will allow at most 5 tuples to be inserted into table. If execution of your query was successful then a non-negative value will be returned.
Note: You may pass multiple queries in one string or query string may be re-written by RULEs.
SPI_exec
returns the result for the last query executed.
The actual number of tuples for which the (last) query was executed is returned in the global variable SPI_processed (if not SPI_OK_UTILITY). If SPI_OK_SELECT is returned and SPI_processed > 0 then you may use global pointer SPITupleTable *SPI_tuptable to access the result tuples.
SPI_exec
may return one of the
following (negative) values:
SPI_ERROR_ARGUMENT if query is NULL or tcount < 0. |
SPI_ERROR_UNCONNECTED if procedure is unconnected. |
SPI_ERROR_COPY if COPY TO/FROM stdin. |
SPI_ERROR_CURSOR if DECLARE/CLOSE CURSOR, FETCH. |
SPI_ERROR_TRANSACTION if BEGIN/ABORT/END. |
SPI_ERROR_OPUNKNOWN if type of query is unknown (this shouldn't occur). |
If SPI_OK_SELECT is returned and SPI_processed > 0 then you may use the global pointer SPITupleTable *SPI_tuptable to access the selected tuples.
Structure SPITupleTable is defined in spi.h:
typedef struct { MemoryContext tuptabcxt; /* memory context of result table */ uint32 alloced; /* # of alloced vals */ uint32 free; /* # of free vals */ TupleDesc tupdesc; /* tuple descriptor */ HeapTuple *vals; /* tuples */ } SPITupleTable;
vals is an array of pointers to tuples (the number of useful entries is given by SPI_processed). TupleDesc tupdesc is a tuple descriptor which you may pass to SPI functions dealing with tuples. tuptabcxt, alloced, and free are internal fields not intended for use by SPI callers.
Note: Functions
SPI_exec
,SPI_execp
andSPI_prepare
change both SPI_processed and SPI_tuptable (just the pointer, not the contents of the structure). Save these two global variables into local procedure variables if you need to access the result of oneSPI_exec
orSPI_execp
across later calls.
SPI_finish
frees all
SPITupleTables allocated during the current procedure. You can
free a particular result table earlier, if you are done with it,
by calling SPI_freetuptable
.