Select the random row function based on DB driver.

data/database.py

@@ -21,8 +21,24 @@ SCHEME_DRIVERS = {
   'postgresql+psycopg2': PostgresqlDatabase,
 }
 
+SCHEME_RANDOM_FUNCTION = {
+  'mysql': fn.Rand,
+  'mysql+pymysql': fn.Rand,
+  'sqlite': fn.Random,
+  'postgresql': fn.Random,
+  'postgresql+psycopg2': fn.Random,  
+}
+
+class CallableProxy(Proxy):
+  def __call__(self, *args, **kwargs):
+    if self.obj is None:
+      raise AttributeError('Cannot use uninitialized Proxy.')
+    return self.obj(*args, **kwargs)
+
 db = Proxy()
 read_slave = Proxy()
+db_random_func = CallableProxy()
+
 
 def _db_from_url(url, db_kwargs):
   parsed_url = make_url(url)
@@ -38,11 +54,15 @@ def _db_from_url(url, db_kwargs):
 
   return SCHEME_DRIVERS[parsed_url.drivername](parsed_url.database, **db_kwargs)
 
+
 def configure(config_object):
   db_kwargs = dict(config_object['DB_CONNECTION_ARGS'])
   write_db_uri = config_object['DB_URI']
   db.initialize(_db_from_url(write_db_uri, db_kwargs))
 
+  parsed_write_uri = make_url(write_db_uri)
+  db_random_func.initialize(SCHEME_RANDOM_FUNCTION[parsed_write_uri.drivername])
+
   read_slave_uri = config_object.get('DB_READ_SLAVE_URI', None)
   if read_slave_uri is not None:
     read_slave.initialize(_db_from_url(read_slave_uri, db_kwargs))

workers/buildlogsarchiver.py

@@ -7,7 +7,7 @@ from gzip import GzipFile
 
 from data import model
 from data.archivedlogs import JSON_MIMETYPE
-from data.database import RepositoryBuild
+from data.database import RepositoryBuild, db_random_func
 from app import build_logs, log_archive
 from util.streamingjsonencoder import StreamingJSONEncoder
 
@@ -22,7 +22,7 @@ def archive_redis_buildlogs():
       avoid needing two-phase commit. """
   try:
     # Get a random build to archive
-    to_archive = model.archivable_buildlogs_query().order_by(fn.Random()).get()
+    to_archive = model.archivable_buildlogs_query().order_by(db_random_func()).get()
     logger.debug('Archiving: %s', to_archive.uuid)
 
     length, entries = build_logs.get_log_entries(to_archive.uuid, 0)