Add NoValidRatesOfChangeException and don't emit ALTER errors for it (#87)

* Add NoValidRatesOfChangeException and don't emit ALTER errors for it

Fixes #86

* Add exception name to warning log

Author: jcjones

partitionmanager/cli.py

@@ -360,8 +360,11 @@ def do_partition(conf):
         except partitionmanager.types.DatabaseCommandException as e:
             log.warning("Failed to automatically handle %s: %s", table, e)
             metrics.add("alter_errors", table.name, 1)
-        except partitionmanager.types.TableEmptyException:
-            log.warning("Table %s appears to be empty. Skipping.", table)
+        except (
+            partitionmanager.types.TableEmptyException,
+            partitionmanager.types.NoValidRatesOfChangeException,
+        ) as e:
+            log.warning("Table %s appears to be empty (%s). Skipping.", table, e)
         except (ValueError, Exception) as e:
             log.warning("Failed to handle %s: %s", table, e)
             metrics.add("alter_errors", table.name, 1)

partitionmanager/table_append_partition.py

@@ -287,7 +287,7 @@ def _get_weighted_position_increase_per_day_for_partitions(partitions):
         log.error(
             "No rates of change were valid for the partition list: %s", partitions
         )
-        raise ValueError("No valid rates of change")
+        raise partitionmanager.types.NoValidRatesOfChangeException
 
     # Initialize a list with a zero for each position
     weighted_sums = [0] * partitions[0].num_columns

partitionmanager/table_append_partition_test.py

@@ -9,6 +9,7 @@
     DuplicatePartitionException,
     NewPlannedPartition,
     NoEmptyPartitionsAvailableException,
+    NoValidRatesOfChangeException,
     InstantPartition,
     SqlInput,
     SqlQuery,
@@ -444,6 +445,12 @@ def test_get_weighted_position_increase_per_day_for_partitions(self):
             ),
             [548.3636363636364],
         )
+        with self.assertRaises(NoValidRatesOfChangeException):
+            _get_weighted_position_increase_per_day_for_partitions(
+                [
+                    mkPPart("p_736563646E64", 1200000),
+                ]
+            )
 
     def test_predict_forward_position(self):
         with self.assertRaises(ValueError):

partitionmanager/types.py

@@ -625,3 +625,7 @@ class DatabaseCommandException(Exception):
 
 class NoExactTimeException(Exception):
     """Raised if there's no exact time available for this partition."""
+
+
+class NoValidRatesOfChangeException(Exception):
+    """Raised if the table's rate of change cannot be calculated."""

pyproject.toml

@@ -7,7 +7,7 @@ name = "mariadb-sequential-partition-manager"
 maintainers = [
   {name = "J.C. Jones", email = "jc@letsencrypt.org"},
 ]
-version = "0.4.0"
+version = "0.4.1"
 description = "Manage DB partitions based on sequential IDs"
 license = {file = "LICENSE.txt"}
 classifiers = [