migrate.py: Add multiple columns simultaneously

(imported from commit 6cd01fcce6a6e18ce57be6f4da1fd394120b1f99)

zerver/lib/migrate.py

@@ -15,43 +15,53 @@ def validate(sql_thingy):
     if not re.match('^[a-z][a-z\d_]+$', sql_thingy):
         raise Exception('Invalid SQL object: %s' % (sql_thingy,))
 
-def do_batch_update(db, table, col, val, batch_size=10000, sleep=0.1):
+def do_batch_update(db, table, cols, vals, batch_size=10000, sleep=0.1):
     validate(table)
+    for col in cols:
         validate(col)
     stmt = '''
         UPDATE %s
-        SET %s = %%s
+        SET (%s) = (%s)
         WHERE id >= %%s AND id < %%s
-    ''' % (table, col)
+    ''' % (table, ', '.join(cols), ', '.join(['%s'] * len(cols)))
+    print stmt
     (min_id, max_id) = db.execute("SELECT MIN(id), MAX(id) FROM %s" % (table,))[0]
     if min_id is None:
         return
+
+    print "%s rows need updating" % (max_id - min_id,)
     while min_id <= max_id:
         lower = min_id
         upper = min_id + batch_size
         print '%s about to update range [%s,%s)' % (time.asctime(), lower, upper)
         db.start_transaction()
-        db.execute(stmt, params=[val, lower, upper])
+        params = list(vals) + [lower, upper]
+        db.execute(stmt, params=params)
         db.commit_transaction()
         min_id = upper
         time.sleep(sleep)
 
-def add_bool_column(db, table, col):
+def add_bool_columns(db, table, cols):
     validate(table)
+    for col in cols:
         validate(col)
     coltype = 'boolean'
     val = 'false'
 
-    stmt = 'ALTER TABLE %s ADD %s %s' % (table, col, coltype)
+    stmt = ('ALTER TABLE %s ' % (table,)) \
+           + ', '.join(['ADD %s %s' % (col, coltype) for col in cols])
     timed_ddl(db, stmt)
 
-    stmt = 'ALTER TABLE %s ALTER %s SET DEFAULT %s' % (table, col, val)
+    stmt = ('ALTER TABLE %s ' % (table,)) \
+           + ', '.join(['ALTER %s SET DEFAULT %s' % (col, val) for col in cols])
     timed_ddl(db, stmt)
 
-    do_batch_update(db, table, col, val)
+    vals = [val] * len(cols)
+    do_batch_update(db, table, cols, vals)
 
     stmt = 'ANALYZE %s' % (table,)
     timed_ddl(db, stmt)
 
-    stmt = 'ALTER TABLE %s ALTER %s SET NOT NULL' % (table, col)
+    stmt = ('ALTER TABLE %s ' % (table,)) \
+           + ', '.join(['ALTER %s SET NOT NULL' % (col,) for col in cols])
     timed_ddl(db, stmt)