问题
I want to create an index which ensures, that I don't have a duplicate serialNr within the combination of amanufacturer + art. But some items don't have a serialNr. These I don't want to check/index.
Code
mySchema.index({ serialNr: 1, art: 1 , manufacturer: 1, deleted: 1}, { unique: true, sparse: true)
I tried it also with adding a partial Filter:
partialFilterExpression: { serialNr: {$ne:null} } to the index options.
Question
How can I index it that inserting:
[{art: 'a', manufacturer:'a', deleted:null}, {art: 'a', manufacturer:'a', deleted:null}] passes
and
[{serialNr: '123', art: 'a', manufacturer:'a', deleted:null}, {serialNr: '123', art: 'a', manufacturer:'a', deleted:null}]fails
I'm not trying to save:
[{serialNr: null, art: 'a', manufacturer:'a', deleted:null}, {serialNr: null, art: 'a', manufacturer:'a', deleted:null}]
The mongo docs state, that it should not be indexed if a field is missing in a compound index:
Sparse indexes selects documents to index solely based on the existence of the indexed field, or for compound indexes, the existence of the indexed fields. https://docs.mongodb.org/manual/core/index-partial/
EDIT:
New Index
implantSchema.index({ serialNr: 1, art: 1 , manufacturer: 1, deleted: 1}, { unique: true, partialFilterExpression: { serialNr: {$exists:true} }})
Before I make changes on the index I drop my collection in my dev-database, to ensure that there is no old index existing. This is the new index which is returned on db.items.getIndexes()
/* 0 */
{
"0" : {
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "LOC_db.items"
},
"1" : {
"v" : 1,
"unique" : true,
"key" : {
"serialNr" : 1,
"art" : 1,
"manufacturer" : 1,
"deleted" : 1
},
"name" : "serialNr_1_art_1_manufacturer_1_deleted_1",
"ns" : "LOC_db.items",
"partialFilterExpression" : {
"serialNr" : {
"$exists" : true
}
},
"background" : true
}
}
Data
- I have a pre save hook where I check the value of
serialNr, which does not exist before, thedup erroris returned. - When querying the database there is no
docexisting which hasnull,""as value for theserialNr. - The query
db.items.find({ serialNr: {$exists:true} })does not match any items.
Error
insertDocument :: caused by :: 11000 E11000 duplicate key error index: LOC_db.items.$serialNr_1_art_1_manufacturer_1_deleted_1 dup key: { : null, : "Robo", : "Olymp", : null }
Additional Information
Maybe the error is related to: https://github.com/Automattic/mongoose/issues/2457
回答1:
You were actually quite close to the solution, all you need to use this when creating index :
partialFilterExpression: { serialNr: {$exists:true} }
Be sure to have at least 3.2 version of mongo
Example :
db.col.createIndex({a:1, b:1},{unique:true, partialFilterExpression: { a: {$exists:true} })
db.col.save({a:50, b:27}) //pass
db.col.save({a:50, b:27}) //fails
db.col.save({b:27}) //pass
db.col.save({b:27}) //pass
db.col.save({b:27}) //pass
db.col.save({a:50, b:27}) //fails
db.col.save({a:50}) //pass
db.col.save({a:50}) //fails
PS : Maybe you can do little "hack" and use this : partialFilterExpression: { serialNr: {$exists:true}, serialNr: {$gte:0} }
I tried using $ne, but it was throwing me an error.
来源：https://stackoverflow.com/questions/35920733/mongoose-compound-index-unique-sparse