How to deal with indexes of multiple where query in firebase? - database

Question

In my flutter app. I have to fetch data from firebase using multiple filters.
I've done as below. It worked but the problem is that some filter is null so I need to skip it in the firebase query, therefore, even I have only 2 fields (name, age) I have to create 3 indexes for supporting my query. 1st index is for: name, 2nd index is for: age, 3rd index is for: name and age.
Future<List<Transac>> getTrans(TransFilter filter, Transac? lastTrans) async {
const limit = 10;
var result =
_collection.orderBy(filter.orderBy, descending: true).limit(limit);
if (filter.directionId != null) {
result = result.where(directionIdKey, isEqualTo: filter.directionId);
}
if (filter.flag != null) {
result = result.where(Transac.flagKey, isEqualTo: filter.flag);
}
if (filter.officeId != null) {
result = result.where(officeIdKey, isEqualTo: filter.officeId);
}
if (lastTrans != null) {
result = result.startAfter([lastTrans.createdAt.millisecondsSinceEpoch]);
}
final _result = await result.get().then(
(value) => value.docs.map((e) => Transac.fromSnapshot(e)).toList());
return _result;
}
I have tried something as below because I think I just need to create all indexs at once, but it throws an error because I cannot use isNotEqualTo on the field that not use in the first orderby.
Future<List<Transac>> getTrans(TransFilter filter, Transac? lastTrans) async {
const limit = 10;
var result =
_collection.orderBy(filter.orderBy, descending: true).limit(limit);
if (filter.directionId != null) {
result = result.where(directionIdKey, isEqualTo: filter.directionId);
}else {
result = result.where(directionIdKey, isNotEqualTo: '');
}
if (filter.officeId != null) {
result = result.where(officeIdKey, isEqualTo: filter.officeId);
}else {
result = result.where(officeIdKey, isNotEqualTo: '');
}
if (lastTrans != null) {
result = result.startAfter([lastTrans.createdAt.millisecondsSinceEpoch]);
}
final _result = await result.get().then(
(value) => value.docs.map((e) => Transac.fromSnapshot(e)).toList());
return _result;
}
Any solution or suggestion? Your help will be much appreciated, Thank you

Answer 1

You have 3 parameters that you want to filterBy directionIdKey, Transac.flagKey, officeIdKey. You want to orderBy: filter.orderBy.
I believe these parameters are holding the field names.
We need a field that will be present in all queries. We use your orderBy field.
So create 3 composite indexes.
filter.orderBy and directionIdKey ASC
filter.orderBy and Transac.flagKey ASC
filter.orderBy and officeIdKey ASC
This should handle your queries.