[cache] Adding description for a zero cache timeout (#5354)

superset/connectors/druid/views.py

@@ -179,6 +179,7 @@ class DruidClusterModelView(SupersetModelView, DeleteMixin, YamlExportMixin):  #
     description_columns = {
         'cache_timeout': _(
             'Duration (in seconds) of the caching timeout for this cluster. '
+            'A timeout of 0 indicates that the cache never expires. '
             'Note this defaults to the global timeout if undefined.'),
     }
 
@@ -256,6 +257,7 @@ class DruidDatasourceModelView(DatasourceModelView, DeleteMixin, YamlExportMixin
             'from the datasource list'),
         'cache_timeout': _(
             'Duration (in seconds) of the caching timeout for this datasource. '
+            'A timeout of 0 indicates that the cache never expires. '
             'Note this defaults to the cluster timeout if undefined.'),
     }
     base_filters = [['id', DatasourceFilter, lambda: []]]

superset/connectors/sqla/views.py

@@ -221,6 +221,7 @@ class TableModelView(DatasourceModelView, DeleteMixin, YamlExportMixin):  # noqa
             'Jinja templating syntax'),
         'cache_timeout': _(
             'Duration (in seconds) of the caching timeout for this table. '
+            'A timeout of 0 indicates that the cache never expires. '
             'Note this defaults to the database timeout if undefined.'),
     }
     label_columns = {

superset/views/core.py

@@ -268,6 +268,7 @@ class DatabaseView(SupersetModelView, DeleteMixin, YamlExportMixin):  # noqa
             'tables, this can be expensive and put strain on the system.'),
         'cache_timeout': _(
             'Duration (in seconds) of the caching timeout for this database. '
+            'A timeout of 0 indicates that the cache never expires. '
             'Note this defaults to the global timeout if undefined.'),
     }
     label_columns = {