Re: Return setof values from C-function - Mailing list pgsql-general

    FuncCallContext *funcctx;

    int call_cntr;

    int max_calls;

    AttInMetadata *attinmeta;

    unsigned long il;

    TupleDesc tupdescRes;

    gsl_histogram * gHist;

    if (SRF_IS_FIRSTCALL())

    {

        size_t nr_rand = strlen ( VARDATA (PG_GETARG_VARCHAR_P(0)));

        char * sql = (char *) palloc (nr_rand+1);

    //    strncpy (sql, (char *)PG_GETARG_VARCHAR_P(0), nr_rand);

        snprintf (sql, nr_rand+1, "%s", VARDATA (PG_GETARG_VARCHAR_P (0)));

        float8 xmin = PG_GETARG_FLOAT8 (1);

        float8 xmax = PG_GETARG_FLOAT8 (2);

        unsigned int num = PG_GETARG_UINT32(3);

        //float8 * result = (float8 *) (palloc (sizeof(float8)));

        //*result= 5.0;

        gHist = gsl_histogram_alloc (num);

        elog (INFO, "query = %s\n", sql);

        gsl_histogram_set_ranges_uniform (gHist, (double)xmin, (double)xmax);

    //    Datum d = PointerGetDatum (gHist);

        SPI_connect ();

        int retVal = SPI_execute (sql, true, 0);

        if (retVal != SPI_OK_SELECT)

        {

            elog (ERROR, "Cannot load values");

            SPI_finish ();

            PG_RETURN_NULL();

        }

        elog (INFO, "%d\n", retVal);

        unsigned long int nproc = SPI_processed;

        elog (INFO, "number of points is %lu, number of bins is %u", nproc, num);

    //    SPI_finish ();

    //    pfree (sql);

    //    PG_RETURN_NULL();

        int i=0;

        TupleDesc tupdesc = SPI_tuptable->tupdesc;

        for (; i< nproc; i++)

        {

            HeapTuple tuple = SPI_tuptable->vals[i];

            int ncolbuf = 1;

            char * x_str = SPI_getvalue (tuple, tupdesc, ncolbuf);

            if (!x_str)

                continue;

            double x= atof (x_str);

            //elog (INFO, "value=%f", x);

            int res = gsl_histogram_increment (gHist, x);

            if (res != 0)

            {

                elog (NOTICE, "Range error, value is %lf, min value is %lf, max value %lf", x, gsl_histogram_min(gHist), gsl_histogram_max (gHist) );

                continue;

            }

        }

        SPI_finish ();

        pfree (sql);

        elog (INFO, "Reading was completed\n");

        MemoryContext   oldcontext;

        funcctx = SRF_FIRSTCALL_INIT();

        oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

        funcctx->max_calls = num;

        Oid * oids = (Oid *)palloc (2*sizeof (Oid));

        oids[0] = INT8OID;

        oids[1] = FLOAT8OID;

        if (get_call_result_type(fcinfo, oids, &tupdescRes) != TYPEFUNC_COMPOSITE)

            ereport(ERROR,

                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),

                     errmsg("function returning record called in context "

                            "that cannot accept type record")));

        attinmeta = TupleDescGetAttInMetadata(tupdescRes);

        funcctx->attinmeta = attinmeta;

        MemoryContextSwitchTo(oldcontext);

        //funcctx->tuple_desc = BlessTupleDesc( tupdescRes );

        pfree (oids);

        elog (INFO, "1st row");

    }

    funcctx = SRF_PERCALL_SETUP();

    call_cntr = funcctx->call_cntr;

    max_calls = funcctx->max_calls;

    elog (INFO, "number of rows = %d, number of columns are %d", max_calls, tupdescRes->natts );

    attinmeta = funcctx->attinmeta;

    HeapTuple tuple;

    if (call_cntr < max_calls)

    {

        elog (INFO, "Rows");

        il = call_cntr;

        //Datum * hvalues = (Datum *)palloc (2*sizeof(Datum));

        char ** svals = (char **) palloc (2*sizeof (char*));

        svals [0] = (char *) palloc(5 * sizeof(char));

        svals [1] = (char *) palloc(20 * sizeof(char));

        double val = gsl_histogram_get (gHist, il);

        snprintf (svals[0], 5, "%lu", il);

        snprintf (svals[1], 20, "%lf", val);

        //hvalues[0] = UInt32GetDatum (il);

        //hvalues[1] = Float8GetDatum (val);

        bool * nulls = palloc( 2 * sizeof( bool ) );

        elog (INFO, "%lu", il);

        tuple = BuildTupleFromCStrings (attinmeta, svals);//heap_form_tuple( tupdescRes, hvalues, nulls);

        elog (INFO, "%lu", il);

        Datum result = HeapTupleGetDatum(tuple);

        pfree (nulls);

        pfree (svals[1]);

        pfree (svals[0]);

        pfree (svals);

        //pfree (hvalues);

        SRF_RETURN_NEXT(funcctx, result);//HeapTupleGetDatum( tuple ) );

    }

    else

    {

        SRF_RETURN_DONE(funcctx);

    }

Thanks a lot.