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 350     Understanding Caching
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 357   <a href="#when-to-use-a-cache" class="md-nav__link">
 358     When to Use a Cache
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 365     When not to Use a Cache
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 808
 809
 810
 811
 812
 813     <li class="md-nav__item">
 814       <a href="../../../javascript/new-api_browser/" class="md-nav__link">
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 816       </a>
 817     </li>
 818
 819
 820
 821
 822
 823
 824
 825     <li class="md-nav__item">
 826       <a href="../../../javascript/new-api_ui/" class="md-nav__link">
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 828       </a>
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 830
 831
 832
 833         </ul>
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 835     </li>
 836
 837
 838
 839
 840
 841
 842
 843     <li class="md-nav__item">
 844       <a href="../../../javascript/legacy-api/" class="md-nav__link">
 845         Legacy API
 846       </a>
 847     </li>
 848
 849
 850
 851
 852
 853
 854
 855     <li class="md-nav__item">
 856       <a href="../../../javascript/helper-functions/" class="md-nav__link">
 857         Helper Functions
 858       </a>
 859     </li>
 860
 861
 862
 863
 864
 865
 866
 867     <li class="md-nav__item">
 868       <a href="../../../javascript/code-snippets/" class="md-nav__link">
 869         Code Snippets
 870       </a>
 871     </li>
 872
 873
 874
 875         </ul>
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 877     </li>
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889     <li class="md-nav__item md-nav__item--nested">
 890
 891
 892         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_5" type="checkbox" id="__nav_5" >
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 894       <label class="md-nav__link" for="__nav_5">
 895         Package Components
 896         <span class="md-nav__icon md-icon"></span>
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 898       <nav class="md-nav" aria-label="Package Components" data-md-level="1">
 899         <label class="md-nav__title" for="__nav_5">
 900           <span class="md-nav__icon md-icon"></span>
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 902         </label>
 903         <ul class="md-nav__list" data-md-scrollfix>
 904
 905
 906
 907
 908
 909     <li class="md-nav__item">
 910       <a href="../../../package/package-xml/" class="md-nav__link">
 911         package.xml
 912       </a>
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 914
 915
 916
 917
 918
 919
 920
 921
 922     <li class="md-nav__item md-nav__item--nested">
 923
 924
 925         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_5_2" type="checkbox" id="__nav_5_2" >
 926
 927       <label class="md-nav__link" for="__nav_5_2">
 928         PIPs
 929         <span class="md-nav__icon md-icon"></span>
 930       </label>
 931       <nav class="md-nav" aria-label="PIPs" data-md-level="2">
 932         <label class="md-nav__title" for="__nav_5_2">
 933           <span class="md-nav__icon md-icon"></span>
 934           PIPs
 935         </label>
 936         <ul class="md-nav__list" data-md-scrollfix>
 937
 938
 939
 940
 941
 942     <li class="md-nav__item">
 943       <a href="../../../package/pip/" class="md-nav__link">
 944         Overview
 945       </a>
 946     </li>
 947
 948
 949
 950
 951
 952
 953
 954     <li class="md-nav__item">
 955       <a href="../../../package/pip/acl-option/" class="md-nav__link">
 956         aclOption
 957       </a>
 958     </li>
 959
 960
 961
 962
 963
 964
 965
 966     <li class="md-nav__item">
 967       <a href="../../../package/pip/acp-menu/" class="md-nav__link">
 968         acpMenu
 969       </a>
 970     </li>
 971
 972
 973
 974
 975
 976
 977
 978     <li class="md-nav__item">
 979       <a href="../../../package/pip/acp-search-provider/" class="md-nav__link">
 980         acpSearchProvider
 981       </a>
 982     </li>
 983
 984
 985
 986
 987
 988
 989
 990     <li class="md-nav__item">
 991       <a href="../../../package/pip/acp-template/" class="md-nav__link">
 992         acpTemplate
 993       </a>
 994     </li>
 995
 996
 997
 998
 999
1000
1001
1002     <li class="md-nav__item">
1003       <a href="../../../package/pip/bbcode/" class="md-nav__link">
1004         bbcode
1005       </a>
1006     </li>
1007
1008
1009
1010
1011
1012
1013
1014     <li class="md-nav__item">
1015       <a href="../../../package/pip/box/" class="md-nav__link">
1016         box
1017       </a>
1018     </li>
1019
1020
1021
1022
1023
1024
1025
1026     <li class="md-nav__item">
1027       <a href="../../../package/pip/clipboard-action/" class="md-nav__link">
1028         clipboardAction
1029       </a>
1030     </li>
1031
1032
1033
1034
1035
1036
1037
1038     <li class="md-nav__item">
1039       <a href="../../../package/pip/core-object/" class="md-nav__link">
1040         coreObject
1041       </a>
1042     </li>
1043
1044
1045
1046
1047
1048
1049
1050     <li class="md-nav__item">
1051       <a href="../../../package/pip/cronjob/" class="md-nav__link">
1052         cronjob
1053       </a>
1054     </li>
1055
1056
1057
1058
1059
1060
1061
1062     <li class="md-nav__item">
1063       <a href="../../../package/pip/event-listener/" class="md-nav__link">
1064         eventListener
1065       </a>
1066     </li>
1067
1068
1069
1070
1071
1072
1073
1074     <li class="md-nav__item">
1075       <a href="../../../package/pip/file/" class="md-nav__link">
1076         file
1077       </a>
1078     </li>
1079
1080
1081
1082
1083
1084
1085
1086     <li class="md-nav__item">
1087       <a href="../../../package/pip/language/" class="md-nav__link">
1088         language
1089       </a>
1090     </li>
1091
1092
1093
1094
1095
1096
1097
1098     <li class="md-nav__item">
1099       <a href="../../../package/pip/media-provider/" class="md-nav__link">
1100         mediaProvider
1101       </a>
1102     </li>
1103
1104
1105
1106
1107
1108
1109
1110     <li class="md-nav__item">
1111       <a href="../../../package/pip/menu/" class="md-nav__link">
1112         menu
1113       </a>
1114     </li>
1115
1116
1117
1118
1119
1120
1121
1122     <li class="md-nav__item">
1123       <a href="../../../package/pip/menu-item/" class="md-nav__link">
1124         menuItem
1125       </a>
1126     </li>
1127
1128
1129
1130
1131
1132
1133
1134     <li class="md-nav__item">
1135       <a href="../../../package/pip/object-type/" class="md-nav__link">
1136         objectType
1137       </a>
1138     </li>
1139
1140
1141
1142
1143
1144
1145
1146     <li class="md-nav__item">
1147       <a href="../../../package/pip/object-type-definition/" class="md-nav__link">
1148         objectTypeDefinition
1149       </a>
1150     </li>
1151
1152
1153
1154
1155
1156
1157
1158     <li class="md-nav__item">
1159       <a href="../../../package/pip/option/" class="md-nav__link">
1160         option
1161       </a>
1162     </li>
1163
1164
1165
1166
1167
1168
1169
1170     <li class="md-nav__item">
1171       <a href="../../../package/pip/page/" class="md-nav__link">
1172         page
1173       </a>
1174     </li>
1175
1176
1177
1178
1179
1180
1181
1182     <li class="md-nav__item">
1183       <a href="../../../package/pip/pip/" class="md-nav__link">
1184         pip
1185       </a>
1186     </li>
1187
1188
1189
1190
1191
1192
1193
1194     <li class="md-nav__item">
1195       <a href="../../../package/pip/script/" class="md-nav__link">
1196         script
1197       </a>
1198     </li>
1199
1200
1201
1202
1203
1204
1205
1206     <li class="md-nav__item">
1207       <a href="../../../package/pip/smiley/" class="md-nav__link">
1208         smiley
1209       </a>
1210     </li>
1211
1212
1213
1214
1215
1216
1217
1218     <li class="md-nav__item">
1219       <a href="../../../package/pip/sql/" class="md-nav__link">
1220         sql
1221       </a>
1222     </li>
1223
1224
1225
1226
1227
1228
1229
1230     <li class="md-nav__item">
1231       <a href="../../../package/pip/style/" class="md-nav__link">
1232         style
1233       </a>
1234     </li>
1235
1236
1237
1238
1239
1240
1241
1242     <li class="md-nav__item">
1243       <a href="../../../package/pip/template/" class="md-nav__link">
1244         template
1245       </a>
1246     </li>
1247
1248
1249
1250
1251
1252
1253
1254     <li class="md-nav__item">
1255       <a href="../../../package/pip/template-listener/" class="md-nav__link">
1256         templateListener
1257       </a>
1258     </li>
1259
1260
1261
1262
1263
1264
1265
1266     <li class="md-nav__item">
1267       <a href="../../../package/pip/user-group-option/" class="md-nav__link">
1268         userGroupOption
1269       </a>
1270     </li>
1271
1272
1273
1274
1275
1276
1277
1278     <li class="md-nav__item">
1279       <a href="../../../package/pip/user-menu/" class="md-nav__link">
1280         userMenu
1281       </a>
1282     </li>
1283
1284
1285
1286
1287
1288
1289
1290     <li class="md-nav__item">
1291       <a href="../../../package/pip/user-notification-event/" class="md-nav__link">
1292         userNotificationEvent
1293       </a>
1294     </li>
1295
1296
1297
1298
1299
1300
1301
1302     <li class="md-nav__item">
1303       <a href="../../../package/pip/user-option/" class="md-nav__link">
1304         userOption
1305       </a>
1306     </li>
1307
1308
1309
1310
1311
1312
1313
1314     <li class="md-nav__item">
1315       <a href="../../../package/pip/user-profile-menu/" class="md-nav__link">
1316         userProfileMenu
1317       </a>
1318     </li>
1319
1320
1321
1322         </ul>
1323       </nav>
1324     </li>
1325
1326
1327
1328
1329
1330
1331
1332     <li class="md-nav__item">
1333       <a href="../../../package/database-php-api/" class="md-nav__link">
1334         Database PHP API
1335       </a>
1336     </li>
1337
1338
1339
1340         </ul>
1341       </nav>
1342     </li>
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354     <li class="md-nav__item md-nav__item--nested">
1355
1356
1357         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6" type="checkbox" id="__nav_6" >
1358
1359       <label class="md-nav__link" for="__nav_6">
1360         Migration
1361         <span class="md-nav__icon md-icon"></span>
1362       </label>
1363       <nav class="md-nav" aria-label="Migration" data-md-level="1">
1364         <label class="md-nav__title" for="__nav_6">
1365           <span class="md-nav__icon md-icon"></span>
1366           Migration
1367         </label>
1368         <ul class="md-nav__list" data-md-scrollfix>
1369
1370
1371
1372
1373
1374
1375     <li class="md-nav__item md-nav__item--nested">
1376
1377
1378         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6_1" type="checkbox" id="__nav_6_1" >
1379
1380       <label class="md-nav__link" for="__nav_6_1">
1381         Migrating from WSC 5.3
1382         <span class="md-nav__icon md-icon"></span>
1383       </label>
1384       <nav class="md-nav" aria-label="Migrating from WSC 5.3" data-md-level="2">
1385         <label class="md-nav__title" for="__nav_6_1">
1386           <span class="md-nav__icon md-icon"></span>
1387           Migrating from WSC 5.3
1388         </label>
1389         <ul class="md-nav__list" data-md-scrollfix>
1390
1391
1392
1393
1394
1395     <li class="md-nav__item">
1396       <a href="../../../migration/wsc53/php/" class="md-nav__link">
1397         PHP API
1398       </a>
1399     </li>
1400
1401
1402
1403
1404
1405
1406
1407     <li class="md-nav__item">
1408       <a href="../../../migration/wsc53/session/" class="md-nav__link">
1409         Session Handling and Authentication
1410       </a>
1411     </li>
1412
1413
1414
1415
1416
1417
1418
1419     <li class="md-nav__item">
1420       <a href="../../../migration/wsc53/javascript/" class="md-nav__link">
1421         JavaScript
1422       </a>
1423     </li>
1424
1425
1426
1427
1428
1429
1430
1431     <li class="md-nav__item">
1432       <a href="../../../migration/wsc53/templates/" class="md-nav__link">
1433         Templates
1434       </a>
1435     </li>
1436
1437
1438
1439
1440
1441
1442
1443     <li class="md-nav__item">
1444       <a href="../../../migration/wsc53/libraries/" class="md-nav__link">
1445         Third Party Libraries
1446       </a>
1447     </li>
1448
1449
1450
1451         </ul>
1452       </nav>
1453     </li>
1454
1455
1456
1457
1458
1459
1460
1461
1462     <li class="md-nav__item md-nav__item--nested">
1463
1464
1465         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6_2" type="checkbox" id="__nav_6_2" >
1466
1467       <label class="md-nav__link" for="__nav_6_2">
1468         Migrating from WSC 5.2
1469         <span class="md-nav__icon md-icon"></span>
1470       </label>
1471       <nav class="md-nav" aria-label="Migrating from WSC 5.2" data-md-level="2">
1472         <label class="md-nav__title" for="__nav_6_2">
1473           <span class="md-nav__icon md-icon"></span>
1474           Migrating from WSC 5.2
1475         </label>
1476         <ul class="md-nav__list" data-md-scrollfix>
1477
1478
1479
1480
1481
1482     <li class="md-nav__item">
1483       <a href="../../../migration/wsc52/php/" class="md-nav__link">
1484         PHP API
1485       </a>
1486     </li>
1487
1488
1489
1490
1491
1492
1493
1494     <li class="md-nav__item">
1495       <a href="../../../migration/wsc52/templates/" class="md-nav__link">
1496         Templates and Languages
1497       </a>
1498     </li>
1499
1500
1501
1502
1503
1504
1505
1506     <li class="md-nav__item">
1507       <a href="../../../migration/wsc52/libraries/" class="md-nav__link">
1508         Third Party Libraries
1509       </a>
1510     </li>
1511
1512
1513
1514         </ul>
1515       </nav>
1516     </li>
1517
1518
1519
1520
1521
1522
1523
1524
1525     <li class="md-nav__item md-nav__item--nested">
1526
1527
1528         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6_3" type="checkbox" id="__nav_6_3" >
1529
1530       <label class="md-nav__link" for="__nav_6_3">
1531         Migrating from WSC 3.1
1532         <span class="md-nav__icon md-icon"></span>
1533       </label>
1534       <nav class="md-nav" aria-label="Migrating from WSC 3.1" data-md-level="2">
1535         <label class="md-nav__title" for="__nav_6_3">
1536           <span class="md-nav__icon md-icon"></span>
1537           Migrating from WSC 3.1
1538         </label>
1539         <ul class="md-nav__list" data-md-scrollfix>
1540
1541
1542
1543
1544
1545     <li class="md-nav__item">
1546       <a href="../../../migration/wsc31/php/" class="md-nav__link">
1547         PHP API
1548       </a>
1549     </li>
1550
1551
1552
1553         </ul>
1554       </nav>
1555     </li>
1556
1557
1558
1559
1560
1561
1562
1563
1564     <li class="md-nav__item md-nav__item--nested">
1565
1566
1567         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6_4" type="checkbox" id="__nav_6_4" >
1568
1569       <label class="md-nav__link" for="__nav_6_4">
1570         Migrating from WSC 3.0
1571         <span class="md-nav__icon md-icon"></span>
1572       </label>
1573       <nav class="md-nav" aria-label="Migrating from WSC 3.0" data-md-level="2">
1574         <label class="md-nav__title" for="__nav_6_4">
1575           <span class="md-nav__icon md-icon"></span>
1576           Migrating from WSC 3.0
1577         </label>
1578         <ul class="md-nav__list" data-md-scrollfix>
1579
1580
1581
1582
1583
1584     <li class="md-nav__item">
1585       <a href="../../../migration/wsc30/php/" class="md-nav__link">
1586         PHP API
1587       </a>
1588     </li>
1589
1590
1591
1592
1593
1594
1595
1596     <li class="md-nav__item">
1597       <a href="../../../migration/wsc30/javascript/" class="md-nav__link">
1598         JavaScript API
1599       </a>
1600     </li>
1601
1602
1603
1604
1605
1606
1607
1608     <li class="md-nav__item">
1609       <a href="../../../migration/wsc30/templates/" class="md-nav__link">
1610         Templates
1611       </a>
1612     </li>
1613
1614
1615
1616
1617
1618
1619
1620     <li class="md-nav__item">
1621       <a href="../../../migration/wsc30/css/" class="md-nav__link">
1622         CSS
1623       </a>
1624     </li>
1625
1626
1627
1628
1629
1630
1631
1632     <li class="md-nav__item">
1633       <a href="../../../migration/wsc30/package/" class="md-nav__link">
1634         Package Components
1635       </a>
1636     </li>
1637
1638
1639
1640         </ul>
1641       </nav>
1642     </li>
1643
1644
1645
1646
1647
1648
1649
1650
1651     <li class="md-nav__item md-nav__item--nested">
1652
1653
1654         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_6_5" type="checkbox" id="__nav_6_5" >
1655
1656       <label class="md-nav__link" for="__nav_6_5">
1657         Migrating from WCF 2.1
1658         <span class="md-nav__icon md-icon"></span>
1659       </label>
1660       <nav class="md-nav" aria-label="Migrating from WCF 2.1" data-md-level="2">
1661         <label class="md-nav__title" for="__nav_6_5">
1662           <span class="md-nav__icon md-icon"></span>
1663           Migrating from WCF 2.1
1664         </label>
1665         <ul class="md-nav__list" data-md-scrollfix>
1666
1667
1668
1669
1670
1671     <li class="md-nav__item">
1672       <a href="../../../migration/wcf21/php/" class="md-nav__link">
1673         PHP API
1674       </a>
1675     </li>
1676
1677
1678
1679
1680
1681
1682
1683     <li class="md-nav__item">
1684       <a href="../../../migration/wcf21/templates/" class="md-nav__link">
1685         Templates
1686       </a>
1687     </li>
1688
1689
1690
1691
1692
1693
1694
1695     <li class="md-nav__item">
1696       <a href="../../../migration/wcf21/css/" class="md-nav__link">
1697         CSS
1698       </a>
1699     </li>
1700
1701
1702
1703
1704
1705
1706
1707     <li class="md-nav__item">
1708       <a href="../../../migration/wcf21/package/" class="md-nav__link">
1709         Package Components
1710       </a>
1711     </li>
1712
1713
1714
1715         </ul>
1716       </nav>
1717     </li>
1718
1719
1720
1721         </ul>
1722       </nav>
1723     </li>
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735     <li class="md-nav__item md-nav__item--nested">
1736
1737
1738         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_7" type="checkbox" id="__nav_7" >
1739
1740       <label class="md-nav__link" for="__nav_7">
1741         Tutorials
1742         <span class="md-nav__icon md-icon"></span>
1743       </label>
1744       <nav class="md-nav" aria-label="Tutorials" data-md-level="1">
1745         <label class="md-nav__title" for="__nav_7">
1746           <span class="md-nav__icon md-icon"></span>
1747           Tutorials
1748         </label>
1749         <ul class="md-nav__list" data-md-scrollfix>
1750
1751
1752
1753
1754
1755
1756     <li class="md-nav__item md-nav__item--nested">
1757
1758
1759         <input class="md-nav__toggle md-toggle" data-md-toggle="__nav_7_1" type="checkbox" id="__nav_7_1" >
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1857   <a href="#understanding-caching" class="md-nav__link">
1858     Understanding Caching
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1866     When to Use a Cache
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1872   <a href="#when-not-to-use-a-cache" class="md-nav__link">
1873     When not to Use a Cache
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1896                     <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M20.71 7.04c.39-.39.39-1.04 0-1.41l-2.34-2.34c-.37-.39-1.02-.39-1.41 0l-1.84 1.83 3.75 3.75M3 17.25V21h3.75L17.81 9.93l-3.75-3.75L3 17.25z"/></svg>
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1898
1899
1900                 <h1 id="caches">Caches<a class="headerlink" href="#caches" title="Permanent link">#</a></h1>
1901 <p>WoltLab Suite offers two distinct types of caches:</p>
1902 <ol>
1903 <li><a href="../caches_persistent-caches/">Persistent caches</a> created by cache builders whose data can be stored using different cache sources.</li>
1904 <li><a href="../caches_runtime-caches/">Runtime caches</a> store objects for the duration of a single request.</li>
1905 </ol>
1906 <h2 id="understanding-caching">Understanding Caching<a class="headerlink" href="#understanding-caching" title="Permanent link">#</a></h2>
1907 <p>Every so often, plugins make use of cache builders or runtime caches to store
1908 their data, even if there is absolutely no need for them to do so. Usually, this
1909 involves a strong opinion about the total number of SQL queries on a page,
1910 including but not limited to some magic treshold numbers, which should not be
1911 exceeded for "performance reasons".</p>
1912 <p>This misconception can easily lead into thinking that SQL queries should be
1913 avoided or at least written to a cache, so that it doesn't need to be executed
1914 so often. Unfortunately, this completely ignores the fact that both a single
1915 query can take down your app (e. g. full table scan on millions of rows), but
1916 10 queries using a primary key on a table with a few hundred rows will not slow
1917 down your page.</p>
1918 <p>There are some queries that should go into caches by design, but most of the
1919 cache builders weren't initially there, but instead have been added because
1920 they were required to reduce the load <em>significantly</em>. You need to understand
1921 that caches always come at a cost, even a runtime cache does! In particular,
1922 they will always consume memory that is not released over the duration of the
1923 request lifecycle and potentially even leak memory by holding references to
1924 objects and data structures that are no longer required.</p>
1925 <p>Caching should always be a solution for a problem.</p>
1926 <h3 id="when-to-use-a-cache">When to Use a Cache<a class="headerlink" href="#when-to-use-a-cache" title="Permanent link">#</a></h3>
1927 <p>It's difficult to provide a definite answer or checklist when to use a cache
1928 and why it is required at this point, because the answer is: It depends. The
1929 permission cache for user groups is a good example for a valid cache, where
1930 we can achieve significant performance improvement compared to processing this
1931 data on every request.</p>
1932 <p>Its caches are build for each permutation of user group memberships that are
1933 encountered for a page request. Building this data is an expensive process that
1934 involves both inheritance and specific rules in regards to when a value for a
1935 permission overrules another value. The added benefit of this cache is that one
1936 cache usually serves a large number of users with the same group memberships and
1937 by computing these permissions once, we can serve many different requests. Also,
1938 the permissions are rather static values that change very rarely and thus we can
1939 expect a very high cache lifetime before it gets rebuild.</p>
1940 <h3 id="when-not-to-use-a-cache">When not to Use a Cache<a class="headerlink" href="#when-not-to-use-a-cache" title="Permanent link">#</a></h3>
1941 <p>I remember, a few years ago, there was a plugin that displayed a user's character
1942 from an online video game. The character sheet not only included a list of basic
1943 statistics, but also displayed the items that this character was wearing and or
1944 holding at the time.</p>
1945 <p>The data for these items were downloaded in bulk from the game's vendor servers
1946 and stored in a persistent cache file that periodically gets renewed. There is
1947 nothing wrong with the idea of caching the data on your own server rather than
1948 requesting them everytime from the vendor's servers - not only because they
1949 imposed a limit on the number of requests per hour.</p>
1950 <p>Unfortunately, the character sheet had a sub-par performance and the users were
1951 upset by the significant loading times compared to literally every other page
1952 on the same server. The author of the plugin was working hard to resolve this
1953 issue and was evaluating all kind of methods to improve the page performance,
1954 including deep-diving into the realm of micro-optimizations to squeeze out every
1955 last bit of performance that is possible.</p>
1956 <p>The real problem was the cache file itself, it turns out that it was holding the
1957 data for several thousand items with a total file size of about 13 megabytes.
1958 It doesn't look that much at first glance, after all this isn't the '90s anymore,
1959 but unserializing a 13 megabyte array is really slow and looking up items in such
1960 a large array isn't exactly fast either.</p>
1961 <p>The solution was rather simple, the data that was fetched from the vendor's API
1962 was instead written into a separate database table. Next, the persistent cache
1963 was removed and the character sheet would now request the item data for that
1964 specific character straight from the database. Previously, the character sheet
1965 took several seconds to load and after the change it was done in a fraction of
1966 a second. Although quite extreme, this illustrates a situation where the cache
1967 file was introduced in the design process, without evaluating if the cache -
1968 at least how it was implemented - was really necessary.</p>
1969 <p>Caching should always be a solution for a problem. Not the other way around.</p>
1970
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