assert (catalog_tbl != null);
String sql = SQLUtil.getInsertSQL(catalog_tbl);
PreparedStatement reviewInsert = this.conn.prepareStatement(sql);
//
ZipfianGenerator numReviews = new ZipfianGenerator(num_reviews, 1.8);
ZipfianGenerator reviewer = new ZipfianGenerator(num_users);
int total = 0;
int batch = 0;
for (int i = 0; i < num_items; i++) {
List<Integer> reviewers = new ArrayList<Integer>();
int review_count = numReviews.nextInt();
if (review_count == 0)
review_count = 1; // make sure at least each item has a review
for (int rc = 0; rc < review_count;) {
int u_id = reviewer.nextInt();
if (!reviewers.contains(u_id)) {
rc++;
reviewInsert.setInt(1, total);
reviewInsert.setInt(2, u_id);
reviewInsert.setInt(3, i);