Avoid false positives notifications for observable queries - https://medium.com/google-developers/7-pro-tips-for-room-fbadea4bfbd1

README.md

Avoid false positive notifications for observable queries

For why this happens and more details check out 7 Pro-tips for Room!

LiveDataExtensions.kt

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.observability.persistence.gist

import android.arch.lifecycle.LiveData
import android.arch.lifecycle.MediatorLiveData
import android.arch.lifecycle.Observer

/**
 * LiveData that propagates only distinct emissions.
 */
fun <T> LiveData<T>.getDistinct(): LiveData<T> {
    val distinctLiveData = MediatorLiveData<T>()
    distinctLiveData.addSource(this, object : Observer<T> {
        private var initialized = false
        private var lastObj: T? = null

        override fun onChanged(obj: T?) {
            if (!initialized) {
                initialized = true
                lastObj = obj
                distinctLiveData.postValue(lastObj)
            } else if ((obj == null && lastObj != null) || obj != lastObj) {
                lastObj = obj
                distinctLiveData.postValue(lastObj)
            }
        }
    })

    return distinctLiveData
}

UserDao.kt

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.example.android.observability.persistence.gist

import android.arch.lifecycle.LiveData
import android.arch.persistence.room.Dao
import android.arch.persistence.room.Query
import com.example.android.observability.persistence.User
import io.reactivex.Flowable

/**
 * Data Access Object for the users table.
 */
@Dao
abstract class UserDao {

    /**
     * Get a user by id.

     * @return the user from the table with a specific id.
     */
    @Query("SELECT * FROM Users WHERE userid = :id")
    protected abstract fun getUserById(id: String): LiveData<User>

    fun getUserByIdDistinctLiveData(id: String): LiveData<User> = getUserById(id).getDistinct()

    /**
     * Get a user by id.

     * @return the user from the table with a specific id.
     */
    @Query("SELECT * FROM Users WHERE userid = :id")
    protected abstract fun getUserByIdFlowable(id: String): Flowable<User>

    fun getUserByIdDistinctFlowable(id: String): Flowable<User> =
            getUserByIdFlowable(id)
                    .distinctUntilChanged()
}

You can use instead Transformations.distinctUntilChanged provided by androidx

So code will look like this

@Dao
abstract class UserDao {

    @Query("SELECT * FROM Users WHERE userid = :id")
    protected abstract fun getUserById(id: String): LiveData<User>

     fun getUserByIdDistinctLiveData(id: String): LiveData<User> = Transformations.distinctUntilChanged(getUserById(id))
}

+1

same for Flowable distinctUntilChanged solved my issue.