Apache Spark advisor for real-time advice on notebooks
The Apache Spark advisor analyzes commands and code run by Apache Spark and displays real-time advice for Notebook runs. The Apache Spark advisor has built-in patterns to help users avoid common mistakes. It offers recommendations for code optimization, performs error analysis, and locates the root cause of failures.
Built-in advice
The Spark advisor, a tool integrated with Impulse, provides built-in patterns for detecting and resolving issues in Apache Spark applications. This article explains some of the patterns included in the tool.
You can open the Recent runs pane based on the type of advice you need.
May return inconsistent results when using 'randomSplit'
Inconsistent or inaccurate results may be returned when working with 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. Where each sample refetches, partitions, and sorts 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.
Unable to recognize a hint
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.
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.
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.
"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.
User experience
The Apache Spark advisor displays the advice, including info, warnings, and errors, at Notebook cell output in real-time.
Info
Warning
Error
Spark Advisor Setting
The Spark advisor setting allows you to choose whether to show or hide specific types of Spark advice according to your needs. Additionally, you have the flexibility to enable or disable the Spark Advisor for your Notebooks within a workspace, based on your preferences.
You can access the Spark Advisor settings at the Fabric Notebook level to enjoy its benefits and ensure a productive notebook authoring experience.
