Merge pull request #208981 from BCS2022/apache-spark-advisor

Edit pass: Apache spark advisor

Author: denrea

articles/synapse-analytics/monitoring/apache-spark-advisor.md

@@ -1,6 +1,6 @@
 ---
-title: Spark Advisor
-description: Spark Advisor is a system to automatically analyze commands/queries, and show the appropriate advice when a customer executes code or query.
+title: Troubleshoot Spark application issues with Spark Advisor
+description: Learn how to troubleshoot Spark application issues with Spark Advisor. The advisor automatically analyzes queries and commands, and offers advice.
 services: synapse-analytics 
 author: jejiang
 ms.author: jejiang
@@ -11,56 +11,51 @@ ms.subservice: spark
 ms.date: 06/23/2022
 ---
 
-# Spark Advisor
+# Troubleshoot Spark application issues with Spark Advisor
 
-Spark Advisor is a system to automatically analyze commands/queries, and show the appropriate advice when customer executes code or query. After applying the advice, you would have chance to improve your execution performance, decrease cost and fix the execution failures.
+Spark Advisor is a system that automatically analyzes your code, queries, and commands, and advises you about them. By following this advice, you can improve your execution performance, fix execution failures, and decrease costs. This article helps you solve common problems with Spark Advisor.
 
+## Advice on query hints
 
-## Advice provided
-
-### May return inconsistent results when using 'randomSplit'
-Inconsistent or inaccurate results may be returned when working with the results of the 'randomSplit' method. Use Apache Spark (RDD) caching before using the 'randomSplit' method.
-
-Method randomSplit() is equivalent to performing sample() on your data frame multiple times, with each sample refetching, partitioning, and sorting your data frame within partitions. The data distribution across partitions and sorting order is important for both randomSplit() and sample(). If either changes upon data refetch, there may be duplicates, or missing values across splits and the same sample using the same seed may produce different results.
-
-These inconsistencies may not happen on every run, but to eliminate them completely, cache your data frame, repartition on a column(s), or apply aggregate functions such as groupBy.
-
-### Table/view name is already in use
-A view already exists with the same name as the created table, or a table already exists with the same name as the created view. 
-When this name is used in queries or applications, only the view will be returned no matter, which one created first. To avoid conflicts, rename either the table or the view. 
-
-## Hints related advise
-### Unable to recognize a hint
-The selected query contains a hint that isn't recognized. Verify that the hint is spelled correctly.
+### May return inconsistent results when using 'randomsplit'
+Verify that the hint is spelled correctly.
 
 ```scala
 spark.sql("SELECT /*+ unknownHint */ * FROM t1")
 ```
 
-### Unable to find a specified relation name(s)
-Unable to find the relation(s) specified in the hint. Verify that the relation(s) are spelled correctly and accessible within the scope of the hint.
+### Unable to find specified relation names
+Verify that the relations are spelled correctly and are accessible within the scope of the hint.
 
 ```scala
 spark.sql("SELECT /*+ BROADCAST(unknownTable) */ * FROM t1 INNER JOIN t2 ON t1.str = t2.str")
 ```
 
 ### A hint in the query prevents another hint from being applied
-The selected query contains a hint that prevents another hint from being applied.
 
 ```scala
 spark.sql("SELECT /*+ BROADCAST(t1), MERGE(t1, t2) */ * FROM t1 INNER JOIN t2 ON t1.str = t2.str")
 ```
 
-## Enable 'spark.advise.divisionExprConvertRule.enable' to reduce rounding error propagation
-This query contains the expression with Double type. We recommend that you enable the configuration 'spark.advise.divisionExprConvertRule.enable', which can help reduce the division expressions and to reduce the rounding error propagation.
+### Reduce rounding error propagation caused by division.
+This query contains the expression with the `double` type. We recommend that you enable the configuration `spark.advise.divisionExprConvertRule.enable`, which can help reduce the division expressions and the rounding error propagation.
 
 ```text
 "t.a/t.b/t.c" convert into "t.a/(t.b * t.c)"
 ```
 
-## Enable 'spark.advise.nonEqJoinConvertRule.enable' to improve query performance
-This query contains time consuming join due to "Or" condition within query. We recommend that you enable the configuration 'spark.advise.nonEqJoinConvertRule.enable', which can help to convert the join triggered by "Or" condition to SMJ or BHJ to accelerate this query.
+### Improve query performance for non-equal join. 
+This query contains a time-consuming join because of an `Or` condition within the query. We recommend that you enable the configuration `spark.advise.nonEqJoinConvertRule.enable`. It can help convert the join triggered by the `Or` condition to shuffle sort merge join (SMJ) or broadcast hash join (BHJ) to accelerate this query.
 
-## Next steps
+### The use of the randomSplit method might return inconsistent results
+Spark Advisor might return inconsistent or inaccurate results when you work with the results of the `randomSplit` method. Use Apache Spark resilient distributed dataset caching (RDD) before you use the `randomSplit` method.
+
+The `randomSplit()` method is equivalent to performing a `sample()` action on your DataFrame multiple times, with each sample refetching, partitioning, and sorting your DataFrame within partitions. The data distribution across partitions and sort order is important for both `randomSplit()` and `sample()` methods. If either changes upon data refetch, there might be duplicates or missing values across splits, and the same sample that uses the same seed might produce different results.
+
+These inconsistencies might not happen on every run. To eliminate them completely, cache your DataFrame, repartition on columns, or apply aggregate functions such as `groupBy`.
 
-For more information on monitoring pipeline runs, see the [Monitor pipeline runs using Synapse Studio](how-to-monitor-pipeline-runs.md) article.
+### A table or view name might already be in use
+A view already exists with the same name as the created table, or a table already exists with the same name as the created view. When you use this name in queries or applications, Spark Advisor returns only the view, regardless of which one was created first. To avoid conflicts, rename either the table or the view.
+
+## Next steps
+For more information on monitoring pipeline runs, see [Monitor pipeline runs using Synapse Studio](how-to-monitor-pipeline-runs.md).