ST_CreateOverview
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## Name

ST_CreateOverview — Create an reduced resolution version of a given raster coverage.

## Synopsis

`regclass ST_CreateOverview(`regclass tab, name col, int factor, text algo='NearestNeighbor'`)`;

## Description

Create an overview table with resampled tiles from the source table. Output tiles will have the same size of input tiles and cover the same spatial extent with a lower resolution (pixel size will be 1/`factor` of the original in both directions).

The overview table will be made available in the `raster_overviews` catalog and will have raster constraints enforced.

Algorithm options are: 'NearestNeighbor', 'Bilinear', 'Cubic', 'CubicSpline', and 'Lanczos'. Refer to: GDAL Warp resampling methods for more details.

Availability: 2.2.0

## Example

Output to generally better quality but slower to product format

    SELECT ST_CreateOverview('mydata.mytable'::regclass, 'rast', 2, 'Lanczos');

Output to faster to process default nearest neighbor

    SELECT ST_CreateOverview('mydata.mytable'::regclass, 'rast', 2);

## See Also

ST_Retile, AddOverviewConstraints, AddRasterConstraints, Section 11.2.2, “Raster Overviews”

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