Update doc

Author: wangyum

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -695,8 +695,8 @@ object SQLConf {
   val PARQUET_FILTER_PUSHDOWN_INFILTERTHRESHOLD =
     buildConf("spark.sql.parquet.pushdown.inFilterThreshold")
       .doc("The maximum number of values to filter push-down optimization for IN predicate. " +
-        "Large threshold won't necessarily provide much better performance. " +
-        "The experiment argued that 300 is the limit threshold. " +
+        "Spark will push-down a value greater than or equal to its minimum value and " +
+        "less than or equal to its maximum value if its value exceeds this threshold. " +
         "By setting this value to 0 this feature can be disabled. " +
         s"This configuration only has an effect when '${PARQUET_FILTER_PUSHDOWN_ENABLED.key}' is " +
         "enabled.")

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFilters.scala

@@ -599,7 +599,8 @@ class ParquetFilters(
         createFilterHelper(pred, canPartialPushDownConjuncts = false)
           .map(FilterApi.not)
 
-      case sources.In(name, values) if values.nonEmpty && canMakeFilterOn(name, values.head) =>
+      case sources.In(name, values) if pushDownInFilterThreshold > 0 &&
+        values.nonEmpty && canMakeFilterOn(name, values.head) =>
         if (values.length <= pushDownInFilterThreshold) {
           values.flatMap { v =>
             makeEq.lift(nameToParquetField(name).fieldType)