ST_CountAgg
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## Name

ST_CountAgg — Aggregate. Returns the number of pixels in a given band of a set of rasters. If no band is specified defaults to band 1. If exclude_nodata_value is set to true, will only count pixels that are not equal to the NODATA value.

## Synopsis

`bigint ST_CountAgg(`setof raster rast, integer nband, boolean exclude_nodata_value, double precision sample_percent`)`;

`bigint ST_CountAgg(`setof raster rast, integer nband, boolean exclude_nodata_value`)`;

`bigint ST_CountAgg(`setof raster rast, boolean exclude_nodata_value`)`;

## Description

Returns the number of pixels in a given band of a set of rasters. If no band is specified `nband` defaults to 1.

If `exclude_nodata_value` is set to true, will only count pixels with value not equal to the `NODATA` value of the raster. Set `exclude_nodata_value` to false to get count all pixels

By default will sample all pixels. To get faster response, set `sample_percent` to value between zero (0) and one (1)

Availability: 2.2.0

## Examples

    WITH foo AS (
        SELECT
            rast.rast
        FROM (
            SELECT ST_SetValue(
                ST_SetValue(
                    ST_SetValue(
                        ST_AddBand(
                            ST_MakeEmptyRaster(10, 10, 10, 10, 2, 2, 0, 0,0)
                            , 1, '64BF', 0, 0
                        )
                        , 1, 1, 1, -10
                    )
                    , 1, 5, 4, 0
                )
                , 1, 5, 5, 3.14159
            ) AS rast
        ) AS rast
        FULL JOIN (
            SELECT generate_series(1, 10) AS id
        ) AS id
            ON 1 = 1
    )
    SELECT
        ST_CountAgg(rast, 1, TRUE)
    FROM foo;

     st_countagg
    -------------
              20
    (1 row)

## See Also

ST_Count, ST_SummaryStats, ST_SetBandNoDataValue

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