Adjust README.md

Author: andreasscherman

README.md

@@ -217,14 +217,21 @@ Called once per your Postgres cluster.
   per each slave. If the slave and the master are in synchronous state,
   the replication delay is zero.
 
-
-### Database Local Directory Based (Global) Metrics
-
 * **get_stats_wal_file_amount**:
   This graph shows the amount of files in your database clusters WAL log
   directory (pg_wal or pg_xlog). If the WAL file amount starts to suddenly
   increase, you probably have issues with your WAL archiving process, which
   might lead to the disk filling up, and you database cluster crashing.
+  
+* **get_xid_remaining_ratio, get_multixact_remaining_ratio, get_multixact_members_remaining_ratio**:
+  These metric shows the corresponding remaining % of transaction ids ("xid"), multixact ids ("mxid"), 
+  and multixact members that are available for postgres to use before exhaustion. 
+  Useful for ensuring that the vacuuming is working as intended for your postgres instance.
+
+* **get_multixact_members_per_mxid**:
+  This metric emits the number of multixact members there are per multixact ID. A larger number means
+  that it'll be quicker for the multixact members exhaustion to happen (as can 
+  be seen in **get_multixact_members_usage_ratio**). 
 
 
 ## Short Overview of Python Modules

etc/postgresql-metrics/default/postgresql-metrics.yml

@@ -58,7 +58,7 @@ global_db_functions:
     - ["get_stats_heap_hit_statistics", 60]
     - ["get_stats_replication_delays", 60]
     - ["get_stats_wal_file_amount", 180]
-    - ["get_multixact_members_usage_ratio", 60]
     - ["get_multixact_members_per_mxid", 60]
+    - ["get_multixact_members_remaining_ratio", 60]
     - ["get_multixact_remaining_ratio", 60]
     - ["get_xid_remaining_ratio", 60]

postgresql_metrics/metrics_gatherer.py

@@ -172,7 +172,7 @@ def get_multixact_members_per_mxid(data_dir, db_connection):
     return [metric_multixact_members_per_mxid(members_per_id)]
 
 
-def get_multixact_members_usage_ratio(data_dir, _db_connection):
+def get_multixact_members_remaining_ratio(data_dir, _db_connection):
     members = _get_multixact_members(data_dir)
     ratio = round(members / MAX_MULTIXACT_MEMBERS, 2)
     percentage_remaining = (1.0 - ratio) * 100