migrate: Add do_batch_update method for running batch updates.

* Refactor pgroonga_0002 migration to use new method.

pgroonga/migrations/0002_html_escape_subject.py

@@ -3,19 +3,13 @@ from django.db import models, migrations, connection
 from django.contrib.postgres import operations
 from django.db.backends.postgresql_psycopg2.schema import DatabaseSchemaEditor
 from django.db.migrations.state import StateApps
+from zerver.lib.migrate import do_batch_update
 
 def rebuild_pgroonga_index(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
-    BATCH_SIZE = 10000
-
-    Message = apps.get_model("zerver", "Message")
-    message_ids = Message.objects.values_list('id', flat=True)
     with connection.cursor() as cursor:
-        for i in range(0, len(message_ids), BATCH_SIZE):
-            batch_ids = ', '.join(str(id) for id in message_ids[i:i+BATCH_SIZE])
-            cursor.execute("UPDATE zerver_message SET "
-                           "search_pgroonga = "
-                           "escape_html(subject) || ' ' || rendered_content "
-                           "WHERE id IN (%s)" % (batch_ids,))
+        do_batch_update(cursor, 'zerver_message', ['search_pgroonga'],
+                        ["escape_html(subject) || ' ' || rendered_content"],
+                        escape=False, batch_size=10000)
 
 class Migration(migrations.Migration):
     atomic = False

tools/linter_lib/custom_check.py

@@ -449,6 +449,7 @@ def build_custom_checkers(by_lang):
              'zerver/migrations/0041_create_attachments_for_old_messages.py',
              'zerver/migrations/0060_move_avatars_to_be_uid_based.py',
              'zerver/migrations/0104_fix_unreads.py',
+             'pgroonga/migrations/0002_html_escape_subject.py',
          ]),
          'description': "Don't import models or other code in migrations; see docs/subsystems/schema-migrations.md",
          },

zerver/lib/migrate.py

@@ -1,8 +1,12 @@
-from typing import Any, Callable, Dict, List, Tuple
 from django.db.models.query import QuerySet
+from psycopg2.extensions import cursor
+from typing import Any, Callable, Dict, List, Tuple, TypeVar
+
 import re
 import time
 
+CursorObj = TypeVar('CursorObj', bound=cursor)
+
 def create_index_if_not_exist(index_name: str, table_name: str, column_string: str,
                               where_clause: str) -> str:
     #
@@ -25,3 +29,43 @@ def create_index_if_not_exist(index_name: str, table_name: str, column_string: s
         END$$;
         ''' % (index_name, index_name, table_name, column_string, where_clause)
     return stmt
+
+
+def do_batch_update(cursor: CursorObj,
+                    table: str,
+                    cols: List[str],
+                    vals: List[str],
+                    batch_size: int=10000,
+                    sleep: float=0.1,
+                    escape: bool=True) -> None:  # nocoverage
+    stmt = '''
+        UPDATE %s
+        SET (%s) = (%s)
+        WHERE id >= %%s AND id < %%s
+    ''' % (table, ', '.join(cols), ', '.join(['%s'] * len(cols)))
+
+    cursor.execute("SELECT MIN(id), MAX(id) FROM %s" % (table,))
+    (min_id, max_id) = cursor.fetchall()[0]
+    if min_id is None:
+        return
+
+    print("\n    Range of rows to update: [%s, %s]" % (min_id, max_id))
+    while min_id <= max_id:
+        lower = min_id
+        upper = min_id + batch_size
+        print('    Updating range [%s,%s)' % (lower, upper))
+        params = list(vals) + [lower, upper]
+        if escape:
+            cursor.execute(stmt, params=params)
+        else:
+            cursor.execute(stmt % tuple(params))
+
+        min_id = upper
+        time.sleep(sleep)
+
+        # Once we've finished, check if any new rows were inserted to the table
+        if min_id > max_id:
+            cursor.execute("SELECT MAX(id) FROM %s" % (table,))
+            max_id = cursor.fetchall()[0][0]
+
+    print("    Finishing...", end='')