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| From | Wood Super |
| Date | 05/01/2024 07:49 |
| To | user  |
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Spark Materialized Views: Improve Query Performance and Data Management

[Mich Talebzadeh]

Hi,

I have raised a ticket SPARK-48117
 for enhancing Spark
capabilities with Materialised Views (MV). Currently both Hive and
Databricks support this. I have added these potential benefits  to the
ticket

-* Improved Query Performance (especially for Streaming Data):*
Materialized Views can significantly improve query performance,
particularly for use cases involving Spark Structured Streaming. When
dealing with continuous data streams, materialized views can pre-compute
and store frequently accessed aggregations or transformations. Subsequent
queries on the materialized view can retrieve the results much faster
compared to continuously processing the entire streaming data. This is
crucial for real-time analytics where low latency is essential.
*Enhancing Data Management:* They offer a way to pre-aggregate or transform
data, making complex queries more efficient.
- *Reduced Data Movement*: Materialized Views can be materialized on
specific clusters or storage locations closer to where the data will be
consumed. This minimizes data movement across the network, further
improving query performance and reducing overall processing time.
- *Simplified Workflows:* Developers and analysts can leverage pre-defined
Materialized Views that represent specific business logic or data subsets.
This simplifies data access, reduces development time for queries that rely
on these views, and fosters code reuse.

Please have a look at the ticket and add your comments.

Thanks

Mich Talebzadeh,

Technologist | Architect | Data Engineer  | Generative AI | FinCrime

London
United Kingdom


   view my Linkedin profile


 https://en.everybodywiki.com/Mich_Talebzadeh



Disclaimer: The information provided is correct to the best of my knowledge
but of course cannot be guaranteed . It is essential to note that, as with
any advice, quote "one test result is worth one-thousand expert opinions
(Werner Von Braun)".

Re: Issue with Materialized Views in Spark SQL

[Mich Talebzadeh]

Sadly Apache Spark sounds like it has nothing to do within materialised
views. I was hoping it could read it!

>>> *spark.sql("SELECT * FROM test.mv ").show()*
Traceback (most recent call last):
  File "", line 1, in 
  File "/opt/spark/python/pyspark/sql/session.py", line 1440, in sql
return DataFrame(self._jsparkSession.sql(sqlQuery, litArgs), self)
  File
"/usr/src/Python-3.9.16/venv/venv3.9/lib/python3.9/site-packages/py4j/java_gateway.py",
line 1321, in __call__
return_value = get_return_value(
  File "/opt/spark/python/pyspark/errors/exceptions/captured.py", line 175,
in deco
raise converted from None
*Pyspark.errors.exceptions.captured.AnalysisException: Hive materialized
view is not supported.*


HTH

Mch Talebzadeh,
Technologist | Architect | Data Engineer  | Generative AI | FinCrime
London
United Kingdom


   view my Linkedin profile



 https://en.everybodywiki.com/Mich_Talebzadeh



*Disclaimer:* The information provided is correct to the best of my
knowledge but of course cannot be guaranteed . It is essential to note
that, as with any advice, quote "one test result is worth one-thousand
expert opinions (Werner  Von
Braun )".


On Fri, 3 May 2024 at 11:03, Mich Talebzadeh 
wrote:

> Thanks for the comments I received.
>
> So in summary, Apache Spark itself doesn't directly manage materialized
> views,(MV)  but it can work with them through integration with the
> underlying data storage systems like Hive or through iceberg. I believe
> databricks through unity catalog support MVs as well.
>
> Moreover, there is a case for supporting MVs. However, Spark can utilize
> materialized views even though it doesn't directly manage them.. This came
> about because someone in the Spark user forum enquired about "Spark
> streaming issue to Elastic data*". One option I thought of was that uUsing
> materialized views with Spark Structured Streaming and Change Data Capture
> (CDC) is a potential solution for efficiently streaming view data updates
> in this scenario. .
>
>
> Mich Talebzadeh,
> Technologist | Architect | Data Engineer  | Generative AI | FinCrime
> London
> United Kingdom
>
>
>view my Linkedin profile
> 
>
>
>  https://en.everybodywiki.com/Mich_Talebzadeh
>
>
>
> *Disclaimer:* The information provided is correct to the best of my
> knowledge but of course cannot be guaranteed . It is essential to note
> that, as with any advice, quote "one test result is worth one-thousand
> expert opinions (Werner  Von
> Braun )".
>
>
> On Fri, 3 May 2024 at 00:54, Mich Talebzadeh 
> wrote:
>
>> An issue I encountered while working with Materialized Views in Spark
>> SQL. It appears that there is an inconsistency between the behavior of
>> Materialized Views in Spark SQL and Hive.
>>
>> When attempting to execute a statement like DROP MATERIALIZED VIEW IF
>> EXISTS test.mv in Spark SQL, I encountered a syntax error indicating
>> that the keyword MATERIALIZED is not recognized. However, the same
>> statement executes successfully in Hive without any errors.
>>
>> pyspark.errors.exceptions.captured.ParseException:
>> [PARSE_SYNTAX_ERROR] Syntax error at or near 'MATERIALIZED'.(line 1, pos
>> 5)
>>
>> == SQL ==
>> DROP MATERIALIZED VIEW IF EXISTS test.mv
>> -^^^
>>
>> Here are the versions I am using:
>>
>>
>>
>> *Hive: 3.1.1Spark: 3.4*
>> my Spark session:
>>
>> spark = SparkSession.builder \
>>   .appName("test") \
>>   .enableHiveSupport() \
>>   .getOrCreate()
>>
>> Has anyone seen this behaviour or encountered a similar issue or if there
>> are any insights into why this discrepancy exists between Spark SQL and
>> Hive.
>>
>> Thanks
>>
>> Mich Talebzadeh,
>>
>> Technologist | Architect | Data Engineer  | Generative AI | FinCrime
>>
>> London
>> United Kingdom
>>
>>
>>view my Linkedin profile
>>
>>
>>  https://en.everybodywiki.com/Mich_Talebzadeh
>>
>>
>>
>> Disclaimer: The information provided is correct to the best of my
>> knowledge but of course cannot be guaranteed . It is essential to note
>> that, as with any advice, quote "one test result is worth one-thousand
>> expert opinions (Werner Von Braun)".
>>
>

Help needed optimize spark history server performance

[Vikas Tharyani]

Dear Spark Community,

I'm writing to seek your expertise in optimizing the performance of our
Spark History Server (SHS) deployed on Amazon EKS. We're encountering
timeouts (HTTP 504) when loading large event logs exceeding 5 GB.

*Our Setup:*

   - Deployment: SHS on EKS with Nginx ingress (idle connection timeout: 60
   seconds)
   - Instance: Memory-optimized with sufficient RAM and CPU
   - Spark Daemon Memory: 30 GB
   - Spark History Server Options:
   - K8s Namespace has a limit of 128Gb
   - The backend S3 has a lifecycle policy to delete objects that are older
   than *7 days*.

sparkHistoryOpts:
"-Dspark.history.fs.logDirectory=s3a:///eks-infra-use1/
-Dspark.history.retainedApplications=1
-Dspark.history.ui.maxApplications=20
-Dspark.history.store.serializer=PROTOBUF
-Dspark.hadoop.fs.s3a.threads.max=25
-Dspark.hadoop.fs.s3a.connection.maximum=650
-Dspark.hadoop.fs.s3a.readahead.range=512K
-Dspark.history.fs.endEventReparseChunkSize=2m
-Dspark.history.store.maxDiskUsage=30g"

*Problem:*

   - SHS times out when loading large event logs (8 GB or more).

*Request:*

We would greatly appreciate any insights or suggestions you may have to
improve the performance of our SHS and prevent these timeouts. Here are
some areas we're particularly interested in exploring:

   - Are there additional configuration options we should consider for
   handling large event logs?
   - Could Nginx configuration adjustments help with timeouts?
   - Are there best practices for optimizing SHS performance on EKS?

We appreciate any assistance you can provide.

Thank you for your time and support.

Sincerely,
-- 

Vikas Tharyani

Associate Manager, DevOps

Nielsen

www.nielsen.com 

Re: ********Spark streaming issue to Elastic data**********

[Mich Talebzadeh]

My recommendation! is using materialized views (MVs) created in Hive with
Spark Structured Streaming and Change Data Capture (CDC) is a good
combination for efficiently streaming view data updates in your scenario.

HTH

Mich Talebzadeh,
Technologist | Architect | Data Engineer  | Generative AI | FinCrime
London
United Kingdom


   view my Linkedin profile



 https://en.everybodywiki.com/Mich_Talebzadeh



*Disclaimer:* The information provided is correct to the best of my
knowledge but of course cannot be guaranteed . It is essential to note
that, as with any advice, quote "one test result is worth one-thousand
expert opinions (Werner  Von
Braun )".


On Thu, 2 May 2024 at 21:25, Karthick Nk  wrote:

> Hi All,
>
> Requirements:
> I am working on the data flow, which will use the view definition(view
> definition already defined in schema), there are multiple tables used in
> the view definition. Here we want to stream the view data into elastic
> index based on if any of the table(used in the view definition) data got
> changed.
>
>
> Current flow:
> 1. we are inserting id's from the table(which used in the view definition)
> into the common table.
> 2. From the common table by using the id, we will be streaming the view
> data (by using if any of the incomming id is present in the collective id
> of all tables used from view definition) by using spark structured
> streaming.
>
>
> Issue:
> 1. Here we are facing issue - For each incomming id here we running view
> definition(so it will read all the data from all the data) and check if any
> of the incomming id is present in the collective id's of view result, Due
> to which it is taking more memory in the cluster driver and taking more
> time to process.
>
>
> I am epxpecting an alternate solution, if we can avoid full scan of view
> definition every time, If you have any alternate deisgn flow how we can
> achieve the result, please suggest for the same.
>
>
> Note: Also, it will be helpfull, if you can share the details like
> community forum or platform to discuss this kind of deisgn related topics,
> it will be more helpfull.
>

Re: Issue with Materialized Views in Spark SQL

[Mich Talebzadeh]

Thanks for the comments I received.

So in summary, Apache Spark itself doesn't directly manage materialized
views,(MV)  but it can work with them through integration with the
underlying data storage systems like Hive or through iceberg. I believe
databricks through unity catalog support MVs as well.

Moreover, there is a case for supporting MVs. However, Spark can utilize
materialized views even though it doesn't directly manage them.. This came
about because someone in the Spark user forum enquired about "Spark
streaming issue to Elastic data*". One option I thought of was that uUsing
materialized views with Spark Structured Streaming and Change Data Capture
(CDC) is a potential solution for efficiently streaming view data updates
in this scenario. .


Mich Talebzadeh,
Technologist | Architect | Data Engineer  | Generative AI | FinCrime
London
United Kingdom


   view my Linkedin profile



 https://en.everybodywiki.com/Mich_Talebzadeh



*Disclaimer:* The information provided is correct to the best of my
knowledge but of course cannot be guaranteed . It is essential to note
that, as with any advice, quote "one test result is worth one-thousand
expert opinions (Werner  Von
Braun )".


On Fri, 3 May 2024 at 00:54, Mich Talebzadeh 
wrote:

> An issue I encountered while working with Materialized Views in Spark SQL.
> It appears that there is an inconsistency between the behavior of
> Materialized Views in Spark SQL and Hive.
>
> When attempting to execute a statement like DROP MATERIALIZED VIEW IF
> EXISTS test.mv in Spark SQL, I encountered a syntax error indicating that
> the keyword MATERIALIZED is not recognized. However, the same statement
> executes successfully in Hive without any errors.
>
> pyspark.errors.exceptions.captured.ParseException:
> [PARSE_SYNTAX_ERROR] Syntax error at or near 'MATERIALIZED'.(line 1, pos 5)
>
> == SQL ==
> DROP MATERIALIZED VIEW IF EXISTS test.mv
> -^^^
>
> Here are the versions I am using:
>
>
>
> *Hive: 3.1.1Spark: 3.4*
> my Spark session:
>
> spark = SparkSession.builder \
>   .appName("test") \
>   .enableHiveSupport() \
>   .getOrCreate()
>
> Has anyone seen this behaviour or encountered a similar issue or if there
> are any insights into why this discrepancy exists between Spark SQL and
> Hive.
>
> Thanks
>
> Mich Talebzadeh,
>
> Technologist | Architect | Data Engineer  | Generative AI | FinCrime
>
> London
> United Kingdom
>
>
>view my Linkedin profile
>
>
>  https://en.everybodywiki.com/Mich_Talebzadeh
>
>
>
> Disclaimer: The information provided is correct to the best of my
> knowledge but of course cannot be guaranteed . It is essential to note
> that, as with any advice, quote "one test result is worth one-thousand
> expert opinions (Werner Von Braun)".
>