This function queries the MD5 hash string of a raster object.

Syntax

text ST_MD5Sum(raster raster_obj)

Parameters

Parameter Description
raster_obj The name of the raster object.

Description

The system searches for the metadata of the raster object to obtain the MD5 hash string. If the MD5 hash string cannot be found, the system returns a NULL value. Then, the system calculates the MD5 hash string based on the Alibaba Cloud Object Storage Service (OSS) path where the raster object is stored.

GUC ganos.raster.calculate_md5: specifies whether to calculate the MD5 hash string and saves the string to the metadata when the raster object is stored. Default value: false. For more information, see ganos.raster.calculate_md5.

GUC ganos.raster.md5sum_chunk_size: specifies the size of data that can be cached for each read operation when the system calculates the MD5 hash string. Unit: MB. Default value: 10. For more information, see ganos.raster.md5sum_chunk_size.

Examples

SELECT ST_MD5SUM(rast)
FROM raster_table
WHERE id = 1;

              st_md5sum
-----------------------------------
 21f41fd983d3139c75b04bff2b7bf5c9