FerretDB / FerretDB

FerretDB version

v1.19

Backend

PostgreSQL 13

Environment

OS: Docker for Mac
Deployment: Docker using ghcr.io/ferretdb/ferretdb:1.19.0 image
Deployment details: Docker version 25.0.2

What did you do?

db.survey.insertMany( [
{ "_id": 1, "results": [ { "product": "abc", "score": 10 },
{ "product": "xyz", "score": 5 } ] },
{ "_id": 2, "results": [ { "product": "abc", "score": 8 },
{ "product": "xyz", "score": 7 } ] },
{ "_id": 3, "results": [ { "product": "abc", "score": 7 },
{ "product": "xyz", "score": 8 } ] },
{ "_id": 4, "results": [ { "product": "abc", "score": 7 },
{ "product": "def", "score": 8 } ] }
] );

db.survey.find({}).maxTimeMS(100).count();

What did you expect to see?

Return: 4

In addition to count, all Mongo commands support maxTimeMS, or at least that's what Mongo Node.js driver supports (https://github.com/mongodb/node-mongodb-native/blob/v6.3.0/src/operations/command.ts#L41) so the clients are setting it.

It can be ignored in the parser for now to unblock applications using it. See

FerretDB/internal/handler/common/count.go

Lines 24 to 43 in b6fd73b

    
           // CountParams represents parameters for the count command. 
        
           type CountParams struct { 
        
           	Filter     *types.Document `ferretdb:"query,opt"` 
        
           	DB         string          `ferretdb:"$db"` 
        
           	Collection string          `ferretdb:"count,collection"` 
        
           	Skip  int64 `ferretdb:"skip,opt,positiveNumber"` 
        
           	Limit int64 `ferretdb:"limit,opt,positiveNumber"` 
        
           	Collation *types.Document `ferretdb:"collation,unimplemented"` 
        
           	Fields any `ferretdb:"fields,ignored"` // legacy MongoDB shell adds it, but it is never actually used 
        
           	Hint           any             `ferretdb:"hint,ignored"` 
        
           	ReadConcern    *types.Document `ferretdb:"readConcern,ignored"` 
        
           	Comment        string          `ferretdb:"comment,ignored"` 
        
           	LSID           any             `ferretdb:"lsid,ignored"` 
        
           	ClusterTime    any             `ferretdb:"$clusterTime,ignored"` 
        
           	ReadPreference *types.Document `ferretdb:"$readPreference,ignored"` 
        
           }

and other similar places.

What did you see instead?

MongoServerError: count: unknown field "maxTimeMS" (same for insert, update, delete).

That's strange that the driver sets this field to commands that don't seem to support it. But yeah, we probably should just ignore it, at least for now.

I'd like to try to implement this

	// CountParams represents parameters for the count command.
	type CountParams struct {
	Filter *types.Document `ferretdb:"query,opt"`
	DB string `ferretdb:"$db"`
	Collection string `ferretdb:"count,collection"`

	Skip int64 `ferretdb:"skip,opt,positiveNumber"`
	Limit int64 `ferretdb:"limit,opt,positiveNumber"`

	Collation *types.Document `ferretdb:"collation,unimplemented"`

	Fields any `ferretdb:"fields,ignored"` // legacy MongoDB shell adds it, but it is never actually used

	Hint any `ferretdb:"hint,ignored"`
	ReadConcern *types.Document `ferretdb:"readConcern,ignored"`
	Comment string `ferretdb:"comment,ignored"`
	LSID any `ferretdb:"lsid,ignored"`
	ClusterTime any `ferretdb:"$clusterTime,ignored"`
	ReadPreference *types.Document `ferretdb:"$readPreference,ignored"`
	}