Merge branch 'devel' into feature/apm-112

arangodb · jsteemann · Jul 8, 2021 · Jul 5, 2021 · Jul 5, 2021 · Jul 5, 2021
commit cd1c2ad0bcd15e74d37085afff9decf95cbf786b
diff --git a/CHANGELOG b/CHANGELOG
@@ -22,6 +22,44 @@ devel
   This can be toggled by the startup option `--query.fail-on-warnings` or the 
   per-query runtime option `failOnWarnings`.
 
+* Added new command line-option `--version-json`. This will return the
+  version information as json object.
+
+* Fix ArangoAgency::version(), which always returned an empty string instead
+  of the agency's correctly reported version. This also fixes the agency
+  version in the startup log messages of the cluster.
+
+* Fixed an issue in index selection, when the selectivty estimate of another
+  prefix index was used without checking if the other index covered the
+  FILTER condition.
+
+  For example, given the following indexes:
+
+  - index 1: ["e", "a", "b", "c"]
+  - index 2: ["e", "a", "b"]
+  - index 3: ["d", "e", "f", "g"]
+
+  and the FILTER condition `d == 1 && e == 2 && f == 3`, then the best index
+  to pick would be index 3. However, the optimizer may have picked index 1
+  here. 
+  All indexes are valid candidates for this FILTER condition, but none of the
+  indexes covered all attributes of the FILTER condition. So the index 
+  selectivity estimates were (correctly) not used directly to determine the
+  best index.
+  The actual bug happened when comparing the usefulness of the candidate
+  indexes, when figuring out that even though the selectivity estimate for 
+  index 1 could not be used, but that there existed a prefix index of index
+  1 (index 2). The selecivity estimate of this index was taken _without_
+  checking that prefix index actually satisfied the FILTER condition fully.
+  The prefix index' selectivity estimate must only be used if it fully
+  satisfies the FILTER condition, which was not the case here.
+
+* Add following term ids, which prevents old synchronous replication requests
+  to be accepted after a follower was dropped and has gotten in sync again.
+  This makes the chaos tests which delay synchronous replication requests
+  more reliable and prevent inconsistent shard replicas under bad network
+  conditions.
+
 * Enable process metrics on agent instances by default. Previously, some 
   metrics (including the metrics starting with `arangodb_process` prefix) were
   not returned by agent instances.