The SE_TotalSize() function
The SE_TotalSize() function returns the sum of the in-row and out-of-row components of a geometry.
You can use this function to obtain an estimate of the amount of disk space consumed by one or more geometries. However, this function does not account for dbspace and sbspace overhead, so cannot be used to obtain an exact total.
Syntax
SE_TotalSize(ST_Geometry)Return type
INTEGER