Not using Oplog on mongo 4.0 due to projection?

help
1

Hi all,

encountered a strange phenomenon regarding a pub which publishes an array of cursors. On MontiAPM the traces show, that on two db queries no oplog is used, which usually results in polling instead of pushing that data. I’d like to fix that of course.

The error states:

Some of the field filters are not supported: Projection values should be one of 1, 0, true, or false
Try removing those field filters.

This is obviously false, since in my projection all keys have value of 1 (integer). My query also yields no errors.

Is there a limit on the number of keys in a projection? My fields object has 81 keys right now…

2

Hi, could you post your projection?

I think MontiAPM shows it to you.

Maybe you have something weird in there.

3

Hi,

the projection was

{
  "_id": 1,
  "_groupId": 1,
  "snsID": 1,
  "k._id": 1,
  "k.leh._id": 1,
  "k.leh.kue": 1,
  "k.kla._id": 1,
  "k.kla.kue": 1,
  "k.fa._id": 1,
  "k.fa.kue": 1,
  "k.kpl": 1,
  "k.kID": 1,
  "k.kliste._id": 1,
  "k.kliste.bez": 1,
  "k.kliste.kart": 1,
  "k._sp._id": 1,
  "k._sp._groupId": 1,
  "k._sp.gAb": 1,
  "k._sp.vers": 1,
  "k._sp.name": 1,
  "k._sp.ab.jahr": 1,
  "k._sp.in.kw": 1,
  "k._sp._modifiedAt": 1,
  "rm._id": 1,
  "rm.kue": 1,
  "tag": 1,
  "st._id": 1,
  "st._groupId": 1,
  "st.nr": 1,
  "st.typ": 1,
  "st.reih": 1,
  "st.foAb": 1,
  "st.kbez": 1,
  "st.bez": 1,
  "st.ze": 1,
  "st.da": 1
}

In the meantime I actually fixed this by reducing the number of keys in the projection. Anyway, i’m curious if you find somethings or whats wrong with the projection