This is the second in a series of blogpost on SharePoint Server 2013 in which we will explorer how e-mail alerting works in SharePoint 2013. For part 1 – take a look at SharePoint deep dive exploration: looking into the SharePoint UserInfo table.
If you need to know more about how alerts are working at the lowest level you should take a look at SharePoint 2003 Database tables documentation – for alerts this documentation still seems to be valid. SharePoint stores the list of events for which users have request alerts in the EventCache Table – in comparison to SharePoint 2003 there are some extra fields available (marked in bold). For some of the fields I did not find a
The other tables which are manipulated by the the SharePoint alert framework are EventLog, ImmedSubscriptions, SchedSubscriptions and EventSubsMatches (For an in depth discussion also take a look at the Working with search alerts in SharePoint 2010 ). Every event is recorded in these table but since the EventType and EventData column will contain the most data, these are only filled in when the list has at least one subscription.
So how does this works – there actually is a SharePoint timer job – called the “Immediated Alerts” job which is scheduled to run every 5 minutes. This will pick up the necessary event information and will process it (in batches of 10.000) – if you see issues with alerts not being sent out – I recommend you to take a look at SharePoint Scheduled Alerts Deconstructed
|EventTime||Time when the event record was inserted into the database|
|SiteId||ID of the site, available from the AllSites table|
|WebId||ID of the web, available from the AllWebs table|
|ListId||ID of the list in which the monitored item appears|
|ItemId||ID of the item that raised the event|
|DocId||ID of the document that raised the event|
|ItemName||Full name of the item|
|ItemFullUrl||Full path of the item|
|EventType||ItemAdded(1), Item Modified (2), Item Deleted (4), DiscussionAdded (16), Discussion Modified(32), Discussion Deleted(64), Discussion Closed (128), Discussion Activated (256), …|
|ModifiedBy||User name of the person who raised the event|
|TimeLastModified||Time when the event occurred|
|EventData||The binary large object (BLOB) containing all of the field changes with the old and new values for an item|
|ACL||The ACL for the item at the time it is edited|
The reason why I started looking into these tables because I got feedback from a client that all e-mail alerts which were being sent out had the wrong link in it after we migrated their environment from SharePoint 2007 to 2013. One of the first things that I did was actually sit next to the user who was adding documents in SharePoint and then I noticed something strange. The user uploaded a document and when they needed to fill in extra metadata, they immediately changed the name of the document.
After looking into how alerting works I still did not get an explanation for why the links were sent out correctly before in 2007 – because this should have failed as well. So I used this PowerShell script to create an export of all the e-mail alerts/subscriptions that users had in SharePoint and I noticed that most of the alerts were on just a couple of libraries and then I found it.
In SharePoint 2007, they had a “require check out” set by default on these libraries – this means that when the user uploaded and renamed the document, it was not yet visible to other users and the alert was not send out. If checkout is not required then the files are immediately visible and the “New Item Added” immediate alerts is fired – this was the behavior that they were seeing in 2013.
So the “require checkout” is an interesting workaround to prevent a file from being visible before it is explicitly checked in. Since they were changing the file properties (and even the filename) before the file is visible to users, the New Item alerts would not trigger and users would only be notified of the “Changed Item” alert when the file was checked in.
The reason why we deactivated “require check out” was because of it would conflict with co-authoring but apparently they would never use this feature for these specific libraries for which these alerts were set. So the morale of the story, don’t just activate or change a specific functionality because it is available in a new version but first look at how people are actually using it.
- Use Windows PowerShell to update alerts in SharePoint 2013
- SharePoint scheduled alerts deconstructed
- Working with search alerts in SharePoint 2010