applied Mark Cave-Ayland's new patch that is a bit cleaner and has a

user-defined FETCH limit for creating a histogram.

git-svn-id: http://svn.osgeo.org/postgis/trunk@232 b70326c6-7e19-0410-871a-916f4a2858ee

diff --git a/postgis_estimate.c b/postgis_estimate.c
index 47c5fa3ab6401c22d3079dd59aa7a81cb126e045..4e487d5765ba7ed81ddf13a913e565dc821b332e 100644 (file)
--- a/postgis_estimate.c
+++ b/postgis_estimate.c
@@ -302,6 +302,7 @@ Datum build_histogram2d(PG_FUNCTION_ARGS)
     int    sum_area_numb_new =0;
        int bump=0;
 
+       int tuplimit = 500000;  // No. of tuples returned on each cursor fetch
        bool moredata;
        void *SPIplan;
        void *SPIportal;
@@ -336,8 +337,8 @@ Datum build_histogram2d(PG_FUNCTION_ARGS)
                columnname = DatumGetCString(DirectFunctionCall1(textout,
                                                        PointerGetDatum(PG_GETARG_DATUM(2))));
 
-       elog(NOTICE,"Start build_histogram2d with %i items already existing", sum_area_numb);
-       elog(NOTICE,"table=\"%s\", column = \"%s\"", tablename, columnname);
+       //elog(NOTICE,"Start build_histogram2d with %i items already existing", sum_area_numb);
+       //elog(NOTICE,"table=\"%s\", column = \"%s\"", tablename, columnname);
 
 
                SPIcode = SPI_connect();
@@ -352,7 +353,6 @@ Datum build_histogram2d(PG_FUNCTION_ARGS)
 
                        sprintf(sql,"SELECT box(\"%s\") FROM \"%s\"",columnname,tablename);
                        //elog(NOTICE,"executing %s",sql);
-                       //SPIcode = SPI_exec(sql, 2147483640 ); // max signed int32
 
                        SPIplan = SPI_prepare(sql, 0, NULL);
                        if (SPIplan  == NULL)
@@ -368,19 +368,21 @@ Datum build_histogram2d(PG_FUNCTION_ARGS)
                                        PG_RETURN_NULL() ;
                        }
 
-                       //elog(NOTICE,"processing %i records",SPI_processed);
+                       
                        moredata = TRUE;
-
                        while (moredata==TRUE) {
 
-                               SPI_cursor_fetch(SPIportal, TRUE, 50000);
+                               //elog(NOTICE,"about to fetch...");
+                               SPI_cursor_fetch(SPIportal, TRUE, tuplimit);
 
-                               tuptable = SPI_tuptable;
-                               tupdesc = SPI_tuptable->tupdesc;
                                ntuples = SPI_processed;
+                               //elog(NOTICE,"processing %d records", ntuples);
 
                                if (ntuples > 0) {
 
+                                       tuptable = SPI_tuptable;
+                                       tupdesc = SPI_tuptable->tupdesc;
+
                                        cell_area = ( (xmax-xmin)*(ymax-ymin)/(histo->boxesPerSide*histo->boxesPerSide) );
 
                                        for (t=0;t<ntuples;t++)
@@ -456,6 +458,10 @@ Datum build_histogram2d(PG_FUNCTION_ARGS)
 
                                        } // End of for loop
 
+                                       // Free all the results after each fetch, otherwise all tuples stay
+                                       // in memory until the end of the table...
+                                       SPI_freetuptable(tuptable);
+
                                } else {
                                                moredata = FALSE;
                                } // End of if ntuples > 0
@@ -473,7 +479,7 @@ Datum build_histogram2d(PG_FUNCTION_ARGS)
                                        PG_RETURN_NULL() ;
                }
 
-       //      elog(NOTICE,"finishing up build_histogram2d ");
+               //elog(NOTICE,"finishing up build_histogram2d ");
 
        //pfree(tablename);
        //pfree(columnname);