Github user liancheng commented on a diff in the pull request:
https://github.com/apache/spark/pull/3039#discussion_r19698963
--- Diff: sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala ---
@@ -267,6 +267,23 @@ class SQLContext(@transient val sparkContext:
SparkContext)
}
/**
+ * Unregisters the temporary table with the given table name in the
catalog. If the table has been
+ * cached/persisted before, it can be unpersisted if required.
+ *
+ * @param tableName the name of the table to be unregistered.
+ * @param unpersist whether to unpersist the table if it has been
cached/persisted before.
+ *
+ * @group userf
+ */
+ def unregisterTempTable(tableName: String, unpersist: Boolean = false):
Unit = {
--- End diff --
Because currently a single cached query plan can be shared by multiple
tables:
```scala
testData.select('key).registerTempTable("t1")
testData.select('key).registerTempTable("t2")
cacheTable("t1")
println(isCached("t1")) // true
println(isCached("t2")) // true
unregisterTempTable("t2", unpersist = true)
println(isCached("t1")) // false
println(isCached("t2")) // false
```
Maybe we should unpersist by default? Thoughts?
(Agree with renaming to `dropTempTable`.)
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