Implement count estimate query for postgresdb (#7956)

Content.Server.Database/Model.cs

@@ -174,6 +174,8 @@ namespace Content.Server.Database
         {
             return query.Where(log => EF.Functions.Like(log.Message, "%" + searchText + "%"));
         }
+
+        public abstract int CountAdminLogs();
     }
 
     public class Preference

Content.Server.Database/ModelPostgres.cs

@@ -4,7 +4,7 @@ using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Storage;
-using NpgsqlTypes;
+using Npgsql;
 
 namespace Content.Server.Database
 {
@@ -80,5 +80,15 @@ namespace Content.Server.Database
         {
             return query.Where(log => EF.Functions.ToTsVector("english", log.Message).Matches(searchText));
         }
+
+        public override int CountAdminLogs()
+        {
+            using var command = new NpgsqlCommand("SELECT reltuples FROM pg_class WHERE relname = 'admin_log';", (NpgsqlConnection?) Database.GetDbConnection());
+
+            Database.GetDbConnection().Open();
+            var count = Convert.ToInt32((float) (command.ExecuteScalar() ?? 0));
+            Database.GetDbConnection().Close();
+            return count;
+        }
     }
 }

Content.Server.Database/ModelSqlite.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Globalization;
 using System.IO;
+using System.Linq;
 using System.Net;
 using System.Text;
 using System.Text.Json;
@@ -81,6 +82,11 @@ namespace Content.Server.Database
                 .HasConversion(jsonByteArrayConverter);
         }
 
+        public override int CountAdminLogs()
+        {
+            return AdminLog.Count();
+        }
+
         private static string InetToString(IPAddress address, int mask) {
             if (address.IsIPv4MappedToIPv6)
             {