$projections-$master - constantly being written to

We have hit a problem where the stream
$projections-$master being written to every second (roughly):

When I take a peek inside the $statistics-report, the values are always the same:


“id”: “169afa10268c480c9fbe473638d495ef”,

“statistics”: {

"status": "Running",

"stateReason": "",

"name": "MaintainPendingOrdersBookPartition",

"projectionId": 14,

"epoch": 13,

"version": 14,

"position": "$ce-ProductBucket: 26418",

"progress": 100.0,

"lastCheckpoint": "$ce-ProductBucket: 11594",

"eventsProcessedAfterRestart": 8487,

"checkpointStatus": "",

"partitionsCached": 1,

"effectiveName": "MaintainPendingOrdersBookPartition",

"coreProcessingTime": 53468



We have no active connections to the Event Store, and there is no visible activity on the Event Store except this stream getting hammered.

The disk space is almost out (it’s just a micro server) and we are running a scavenge every two hours.

Anyone any idea what is happening?

Just for some background, we have a service which was reading the projection state (probably every 200ms) to look for new entries.

Could this have resulted in some sort of backlog (and if so, is there a way to verify this)

Thanks in advance.

There should be a $maxAge/$maxCount on here.

  "$tb": 90581

I am sure when we saw the problem before, it was maxAge: 7200

Do you have any idea why it's constantly being written to, even when we don't seem to be interacting with the Event Store?

We think we have the answer to this problem.

The Event Store has been running all morning, constantly writing, then just stopped writing.

Our theory that our “polling” service has been hosing the Event Store and built up some kind of backlog (which has taken hours to process) seems to stand up

The projections tab on the website will be causing those events.


There was on activity (from what we could tell anyway) on the Projections themselves.

We have a service which was reading the projection state frequently, and for each read of the state, we got $state and $statistics-report written