UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >= 0  AND id < 10;
 UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >= 10 AND id < 20;;
  UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >= 20  AND id < 30;

etc...

library(RPostgreSQL)

num <- seq(0, 100, 10)

 query.func <- function(num){

      con <- dbConnect(PostgreSQL(), dbname = "name", post = 5432, user = "user_name", password = "password")

      num2 <- num + 10

       q1 <- paste('UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >=', num, 'AND id <', num2, sep = "")

         dbSendQuery(con, q1)

           dbDisconnect(con)
}

lapply(num, query.func)

no_cores <- detectCores() - 1

 cl <- makeCluster(no_cores)

  clusterExport(cl, "query.func")
  clusterExport(cl, "num")

  clusterEvalQ(cl, library(RPostgreSQL))

    parLapply(cl, num, query.func)

stopCluster()

UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >= 0  AND id < 10;
 UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >= 10 AND id < 20;;
  UPDATE target_table SET col1_target = col1_source FROM source_table WHERE id >= 20  AND id < 30;

UPDATE targate_table set col1_target = col1_source
FROM source_table
WHERE (id BETWEEN 0 AND 10)
  OR (id BETWEEN 10 AND 20)
  OR (id BETWEEN 20 AND 30);