I Opened a Sitecore ticket, and they confirm that the documentation for Sitecore 10.1 (here) will not work, they will update the documentation soon. Meanwhile here's the correct steps provided by their engineers:
- Please, use the attached sample for the patch instead of the code that is used in the article:
- Copy the "Web" folder in the "...App_Data\items" folder
- Rename the folder and the .dat file: use the database name (e.g., web_preview) instead of "web" in the folder name and in the file name (file path should be like "...\web_preview\items.web_preview.dat"
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/"><sitecore><eventing defaultProvider="sitecore"><eventQueueProvider><eventQueue name="web_preview" patch:after="eventQueue[@name='web']" type="Sitecore.Data.Eventing.$(database)EventQueue, Sitecore.Kernel"><param ref="dataApis/dataApi[@name='$(database)']" param1="$(name)" /><param hint="" ref="PropertyStoreProvider/store[@name='$(name)']" /></eventQueue></eventQueueProvider></eventing><PropertyStoreProvider><store name="web_preview" patch:after="store[@name='web']" prefix="web_secondary" getValueWithoutPrefix="true" singleInstance="true" type="Sitecore.Data.Properties.$(database)PropertyStore, Sitecore.Kernel"><param ref="dataApis/dataApi[@name='$(database)']" param1="$(name)" /><param resolve="true" type="Sitecore.Abstractions.BaseEventManager, Sitecore.Kernel" /><param resolve="true" type="Sitecore.Abstractions.BaseCacheManager, Sitecore.Kernel" /></store></PropertyStoreProvider><databases><!-- web_secondary --><database id="web_preview" patch:after="database[@id='web']" singleInstance="true" type="Sitecore.Data.DefaultDatabase, Sitecore.Kernel"><param desc="name">$(id)</param><icon>Images/database_web.png</icon><securityEnabled>true</securityEnabled><dataProviders hint="list:AddDataProvider"><dataProvider type="Sitecore.Data.DataProviders.CompositeDataProvider, Sitecore.Kernel"><param desc="readOnlyDataProviders" hint="list"><protobufItems type="Sitecore.Data.DataProviders.ReadOnly.Protobuf.ProtobufDataProvider, Sitecore.Kernel"><filePaths hint="list"><filePath>$(dataFolder)/items/$(id)</filePath></filePaths></protobufItems></param><param desc="headProvider"><dataProvider ref="dataProviders/main" param1="$(id)"><disableGroup>publishing</disableGroup><prefetch hint="raw:AddPrefetch"><sc.include file="/App_Config/Prefetch/Common.config" /><sc.include file="/App_Config/Prefetch/Webdb.config" /></prefetch></dataProvider></param></dataProvider></dataProviders><PropertyStore ref="PropertyStoreProvider/store[@name='$(id)']" /><remoteEvents.EventQueue><obj ref="eventing/eventQueueProvider/eventQueue[@name='$(id)']" /></remoteEvents.EventQueue><archives hint="raw:AddArchive"><archive name="archive" /><archive name="recyclebin" /></archives><cacheSizes hint="setting"><data>100MB</data><items>50MB</items><paths>2500KB</paths><itempaths>50MB</itempaths><standardValues>2500KB</standardValues></cacheSizes></database></databases></sitecore></configuration>