How to check if changeStreamPreAndPostImages is enabled for a collection

Working with Data
1

Hi Team,

Is there a way to retrieve the information on whether changeStreamPreAndPostImages is enabled/disabled for a collection?

I was able to enable it using runCommand as below. But not sure how to fetch the value that’s been set.

db.runCommand( {
   collMod: "mycollection",
   changeStreamPreAndPostImages: { enabled: true }
} )

Also is there a way to set this changeStreamPreAndPostImages on the database level instead for each collection?

Thanks in advance,
Sabareesh

2

Hi @Sabareesh_Babu,

Will db.getCollectionInfos() work for you?

Please view the example below where I create a collection, run db.getCollectionInfos() to check the options on the collections in the database, enable the changeStreamPreAndPostImages option on the created collection and then finally run db.getCollectionInfos() again to check the options on the collection:

db> show collections

db> db.createCollection("collection")
{ ok: 1 }

db> db.getCollectionInfos()
[
  {
    name: 'collection',
    type: 'collection',
    options: {},
    info: {
      readOnly: false,
      uuid: new UUID("85ec92c3-16da-41db-bd42-07654f449a46")
    },
    idIndex: { v: 2, key: { _id: 1 }, name: '_id_' }
  }
]

/// Setting changeStreamPreAndPostImages option
db> db.runCommand({collMod:"collection",changeStreamPreAndPostImages: { enabled: true } })
{
  ok: 1,
  ...
}

Output from db.getCollectionInfos() after setting the option:

db> db.getCollectionInfos()
[
  {
    name: 'collection',
    type: 'collection',
    options: { changeStreamPreAndPostImages: { enabled: true } }, /// <--- option enabled
    info: {
      readOnly: false,
      uuid: new UUID("85ec92c3-16da-41db-bd42-07654f449a46")
    },
    idIndex: { v: 2, key: { _id: 1 }, name: '_id_' }
  }
]

To my knowledge I haven’t seen if there is a way to do this at the database level.

Regards,
Jason

3

Thanks Jason. Is there an equivalent C++ API for getCollectionInfos?
I was looking into mongoc_collection_t - libmongoc 2.1.0 but couldn’t find one.

4

Not certain but can you try this one out: mongoc_database_find_collections_with_opts() - libmongoc 1.25.1

Otherwise I can check with the team :slight_smile:

The db.getCollectionInfos() is a helper for mongosh but it’s output is similar to that of listCollections. i.e. db.runCommand({listCollections:1}) also shows the collection information including the options.

Hope this helps and look forward to hearing from you.

Regards,
Jason

5

Thanks for the quick response.Will check mongoc_database_find_collections_with_opts.

1 Like
6

Cool - If it works, try and update this post so that it hopefully helps others using the same in future :slight_smile:

7

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