The ST_PixelData type can be maintained as a separate entity, which makes it possible to copy the pixel array of an ST_Raster value to an ST_PixelData value.
The ST_PixelData type can be used to edit the data stored in an ST_Raster object. The basic workflow for doing so is to fetch the data from an ST_Raster value into an ST_PixelData value, edit it, then transfer it back to the ST_Raster value.
The ST_PixelData value can be temporarily persisted as a DBMS Procedural Language variable, or it can be permanently persisted in an ST_PixelData column.
The pixels of an ST_PixelData value can be edited, but only after they have been read into a variable. The ST_PixelData can be read into a variable either from an ST_Raster column or from an ST_PixelData column. An ST_PixelData variable can also be instantiated through the ST_PixelData constructor.
The value of a ST_PixelData variable can be stored directly in the ST_Raster column or in an ST_PixelData column.