Psql parallel processing in Bash

parallel.sh

#!/bin/bash

workers=4
STEP=$(psql -U svetluska -c "SELECT ceil(COUNT(*) / $workers) FROM svetluska.domination" -qtA  svetluska)

time for ((i=0; i<$workers; i++))
do 
  echo "UPDATE svetluska.domination SET geometry = t.geometry_wkt FROM (SELECT id, geometry_wkt FROM svetluska.domination ORDER BY id LIMIT $STEP OFFSET $STEP*$i) t WHERE domination.id = t.id"; 
done | xargs -P $workers -I % psql -U svetluska -c "%" svetluska
#done | xargs -P 3 -I % echo %