Github user liancheng commented on a diff in the pull request:

    https://github.com/apache/spark/pull/8023#discussion_r37427369
  
    --- Diff: 
sql/core/src/main/scala/org/apache/spark/sql/execution/CacheManager.scala ---
    @@ -156,10 +165,27 @@ private[sql] class CacheManager(sqlContext: 
SQLContext) extends Logging {
        * function will over invalidate.
        */
       private[sql] def invalidateCache(plan: LogicalPlan): Unit = writeLock {
    -    cachedData.foreach {
    -      case data if data.plan.collect { case p if p.sameResult(plan) => p 
}.nonEmpty =>
    -        data.cachedRepresentation.recache()
    -      case _ =>
    +    var i = 0
    +    var locatedIdx = -1
    +    // find the index of the cached data, according to the specified 
logical plan
    +    while (i < cachedData.length && locatedIdx < 0) {
    +      cachedData(i) match {
    +        case data if data.plan.collect { case p if p.sameResult(plan) => p 
}.nonEmpty =>
    +          locatedIdx = i
    +        case _ =>
    +      }
    +      i += 1
    +    }
    +
    +    if (locatedIdx >= 0) {
    +      // if the cached data exists, remove it from the cache data list, as 
we need to
    +      // re-generate the spark plan, and we don't want the this to be used 
during the
    +      // re-generation
    +      val entry = cachedData.remove(locatedIdx) // TODO do we have to use 
ArrayBuffer?
    +      // rebuild the cache
    +      entry.recache(sqlContext)
    +      // add it back to the cache data list
    +      cachedData += entry
    --- End diff --
    
    A problem of this change is that, `plan` can appear multiple times in 
`cachedData`. For example (PySpark snippet):
    
    ```python
    df0 = sqlContext.range(10)
    df1 = df0.filter(df0.id > 5).cache()
    df2 = df0.filter(df0.id > 1).cache()
    
    df1.count()
    df2.count()
    ```
    
    In the above case, query plan of `df0` appears twice in `df1` and `df2`. 
Since this method isn't performance critical, we can correct and simplify the 
block within `writeLock` to:
    
    ```scala
        cachedData.foreach { cached =>
          if (cached.plan.find(_.sameResult(plan)).isDefined) {
            cached.recache()
          }
        }
    ```


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