A subset of blocks from a set of blocks of a memory device are identified based on a valid data count constraint. A first block from the subset of blocks is selected based on a valid data count of the first block. A second block from the subset of blocks is selected based on a data temperature of the second block. A comparison of the first block and the second block is performed in accordance with one or more comparison criterion. The first block or the second block is selected as a garbage collection source block based on the comparison. Garbage collection is performed at the garbage collection source block.