From 36af579f7cec61bc45bae1a8a8f947e4e8a1a810 Mon Sep 17 00:00:00 2001
From: Daoud Clarke <daoud.clarke@gmail.com>
Date: Sat, 31 Dec 2022 17:04:38 +0000
Subject: [PATCH] Sample domains

---
 mwmbl/crawler/urls.py | 47 ++++++++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 21 deletions(-)

diff --git a/mwmbl/crawler/urls.py b/mwmbl/crawler/urls.py
index 9236ca8..6c16e35 100644
--- a/mwmbl/crawler/urls.py
+++ b/mwmbl/crawler/urls.py
@@ -1,6 +1,7 @@
 """
 Database storing info on URLs
 """
+import random
 from dataclasses import dataclass
 from datetime import datetime, timedelta
 from enum import Enum
@@ -130,35 +131,39 @@ class URLDatabase:
         start = datetime.utcnow()
         logger.info("Getting URLs for crawling")
 
+        work_mem = "SET work_mem = '512MB'"
+
         sql = f"""
-        UPDATE urls SET status = {URLStatus.QUEUED.value}, updated = %(now)s
-        WHERE url IN (
-          SELECT url FROM url_and_hosts
-              WHERE host = %(domain)s
-              AND status IN ({URLStatus.NEW.value}) OR (
-                  status = {URLStatus.ASSIGNED.value} AND updated < %(min_updated_date)s
-              )
-              ORDER BY score DESC
-              LIMIT {MAX_TOP_DOMAIN_URLS}
-          )
-        )
-        RETURNING url
-        """
+         UPDATE urls SET status = {URLStatus.QUEUED.value}, updated = %(now)s
+         WHERE url IN (
+           SELECT url FROM (
+               SELECT url, host, score, rank() OVER (PARTITION BY host ORDER BY score DESC) AS pos
+               FROM url_and_hosts
+               WHERE host IN %(domains)s
+               AND status IN ({URLStatus.NEW.value}) OR (
+                   status = {URLStatus.ASSIGNED.value} AND updated < %(min_updated_date)s
+               )
+           ) u
+           WHERE pos < {MAX_TOP_DOMAIN_URLS}
+         )
+         RETURNING url
+         """
 
         now = datetime.utcnow()
         min_updated_date = now - timedelta(hours=REASSIGN_MIN_HOURS)
-        domains = tuple(DOMAINS.keys())
-
-        results = []
-        for domain in domains:
-            with self.connection.cursor() as cursor:
-                cursor.execute(sql, {'min_updated_date': min_updated_date, 'now': now, 'domain': domain})
-                domain_results = cursor.fetchall()
-                results += [result[0] for result in domain_results]
+        domains = tuple(random.sample(DOMAINS.keys(), 100))
+        logger.info(f"Getting URLs for domains {domains}")
+        with self.connection.cursor() as cursor:
+            cursor.execute(work_mem)
+            cursor.execute(sql,
+                           {'min_updated_date': min_updated_date, 'now': now, 'num_urls': num_urls, 'domains': domains})
+            results = cursor.fetchall()
 
+        results = [result[0] for result in results]
         total_time_seconds = (datetime.now() - start).total_seconds()
         logger.info(f"Got {len(results)} in {total_time_seconds} seconds")
 
+        random.shuffle(results)
         return results
 
     def get_urls(self, status: URLStatus, num_urls: int):