Remove unused guild data after a period of inactivity

BirthdayBot/BackgroundServiceRunner.vb

@@ -17,7 +17,8 @@ Class BackgroundServiceRunner
         Workers = New List(Of BackgroundService) From {
             {New GuildStatistics(instance)},
             {New Heartbeat(instance)},
-            {BirthdayUpdater}
+            {BirthdayUpdater},
+            {New StaleDataCleaner(instance)}
         }
     End Sub
 

BirthdayBot/BackgroundServices/StaleDataCleaner.vb

@@ -0,0 +1,39 @@
+Imports Npgsql
+''' <summary>
+''' Automatically removes database information for guilds that have not been accessed in a long time.
+''' </summary>
+Class StaleDataCleaner
+    Inherits BackgroundService
+
+    Public Sub New(instance As BirthdayBot)
+        MyBase.New(instance)
+    End Sub
+
+    Public Overrides Async Function OnTick() As Task
+        Using db = Await BotInstance.Config.DatabaseSettings.OpenConnectionAsync()
+            ' Update only for all guilds the bot has cached
+            Using c = db.CreateCommand()
+                c.CommandText = $"update {GuildStateInformation.BackingTable} set last_seen = now() " +
+                    "where guild_id = @Gid"
+                Dim updateGuild = c.Parameters.Add("@Gid", NpgsqlTypes.NpgsqlDbType.Bigint)
+                c.Prepare()
+
+                Dim list As New List(Of ULong)(BotInstance.GuildCache.Keys)
+                For Each id In list
+                    updateGuild.Value = CLng(id)
+                    c.ExecuteNonQuery()
+                Next
+            End Using
+
+            ' Delete all old values - expects referencing tables to have 'on delete cascade'
+            Using t = db.BeginTransaction()
+                Using c = db.CreateCommand()
+                    ' Delete data for guilds not seen in 2 weeks
+                    c.CommandText = $"delete from {GuildUserSettings.BackingTable} where (now() - interval '14 days') > last_seen"
+                    Dim r = c.ExecuteNonQuery()
+                    If r <> 0 Then Log($"Removed {r} stale guild(s).")
+                End Using
+            End Using
+        End Using
+    End Function
+End Class

BirthdayBot/BirthdayBot.vbproj

@@ -4,7 +4,7 @@
     <OutputType>Exe</OutputType>
     <RootNamespace>BirthdayBot</RootNamespace>
     <TargetFramework>netcoreapp2.0</TargetFramework>
-    <Version>1.4.1</Version>
+    <Version>1.4.2</Version>
     <Authors>Noi</Authors>
     <Company />
     <Description>Discord bot for birthday reminders.</Description>

BirthdayBot/Data/GuildStateInformation.vb

@@ -320,13 +320,14 @@ Class GuildStateInformation
                 "moderator_role bigint null, " +
                 "announce_message text null, " +
                 "announce_message_pl text null, " +
-                "announce_ping boolean not null default FALSE" +
+                "announce_ping boolean not null default FALSE, " +
+                "last_seen timestamptz not null default NOW()" +
                 ")"
             c.ExecuteNonQuery()
         End Using
         Using c = db.CreateCommand()
             c.CommandText = $"create table if not exists {BackingTableBans} (" +
-                $"guild_id bigint not null references {BackingTable}, " +
+                $"guild_id bigint not null references {BackingTable} ON DELETE CASCADE, " +
                 "user_id bigint not null, " +
                 "PRIMARY KEY (guild_id, user_id)" +
                 ")"

BirthdayBot/Data/GuildUserSettings.vb

@@ -125,7 +125,7 @@ Class GuildUserSettings
     Friend Shared Sub SetUpDatabaseTable(db As NpgsqlConnection)
         Using c = db.CreateCommand()
             c.CommandText = $"create table if not exists {BackingTable} (" +
-                $"guild_id bigint not null references {GuildStateInformation.BackingTable}, " +
+                $"guild_id bigint not null references {GuildStateInformation.BackingTable} ON DELETE CASCADE, " +
                 "user_id bigint not null, " +
                 "birth_month integer not null, " +
                 "birth_day integer not null, " +