I have a Spark code programmed in Scala. My code reads an xml and extracts all the info in it. The goal is to store the info from the XML into Redshift tables.
Is it possible to send the data directly from my Scala Spark code to Redshift without using S3?
Cheers!
If you're using Spark SQL you can read your XML data into DataFrame using spark-xml and then writing it into Redshift tables using spark-redshift .
You can also take a look on this question .
You can do row level insert using pre-prepared SQL statements into your Python/ Java code, but it will be extremely inefficient if you are going to insert more than few records.
Related
I am creating a data warehouse using Azure Data Factory to extract data from a MySQL table and saving it in parquet format in an ADLS Gen 2 filesystem. From there, I use Synapse notebooks to process and load data into destination tables.
The initial load is fairly easy using spark.write.saveAsTable('orders') however, I am running into some issues doing incremental load following the intial load. In particular, I have not been able to find a way to reliably insert/update information into an existing Synapse table.
Since Spark does not allow DML operations on a table, I have resorted to reading the current table into a Spark DataFrame and inserting/updating records in that DataFrame. However, when I try to save that DataFrame using spark.write.saveAsTable('orders', mode='overwrite', format='parquet'), I run into a Cannot overwrite table 'orders' that is also being read from error.
A solution indicated by this suggests creating a temporary table and then inserting using that but that still resorts in the above error.
Another solution in this post suggests to write the data into a temporary table, drop the target table, and then rename the table but upon doing this, Spark gives me a FileNotFound errors regarding metadata.
I know Delta Tables can fix this issue pretty reliably but our company is not yet ready to move over to DataBricks.
All suggestions are greatly appreciated.
I'm trying to achieve something similar using spark and scala
Updating BigQuery data using Java
https://cloud.google.com/bigquery/docs/updating-data
I want to update existing data and also insert new data into Bigquery table. Any ideas if we can using some sort of DML within spark to do an upsert operation against BigQuery ??
I found that BigQuery supports merge but I'm not sure if we can do something similar using spark and scala
Google BQ - how to upsert existing data in tables?
The spark API does not support upsert yet. The best workaround at this moment is to write the dataframe to a temporary table, run a MERGE job and then delete the temporary table.
How could you access the HIVE ACID table, in Spark sql?
We have worked on and open sourced a datasource that will enable users to work on their Hive ACID Transactional tables using Spark.
Github: https://github.com/qubole/spark-acid
It is available as a Spark package and instructions to use it are on the Github page. Currently the datasource supports only reading from Hive ACID tables, and we are working on adding the ability to write into these tables via Spark as well.
Feedback and suggestions are welcome!
#aniket Spark doesn't support reading Hive Acid tables directly. (https://issues.apache.org/jira/browse/SPARK-15348/SPARK-16996)
The data layout for transactional tables requires special logic to decide which directories to read and how to combine them correctly. Some data files may represent updates of previously written rows, for example. Also, if you are reading while something is writing to this table your read may fail (w/o the special logic) because it will try to read incomplete ORC files. Compaction may (again w/o the special logic) may make it look like your data is duplicated.
It can be done (WIP) via LLAP - tracked in https://issues.apache.org/jira/browse/HIVE-12991
I faced the same issue (Spark for Hive acid tables )and I can able to manage with JDBC call from Spark. May be I can use this JDBC call from spark until we get the native ACID support from Spark.
https://github.com/Gowthamsb12/Spark/blob/master/Spark_ACID
Spark can read acid table directly at least since spark 2.3.2. But I can aslo confirm it can't read acid table in spark 2.2.0.
I have little experience in Hive and currently learning Spark with Scala. I am curious to know whether Hive on Tez really faster than SparkSQL. I searched many forums with test results but they have compared older version of Spark and most of them are written in 2015. Summarized main points below
ORC will do the same as parquet in Spark
Tez engine will give better performance like Spark engine
Joins are better/faster in Hive than Spark
I feel like Hortonworks supports more for Hive than Spark and Cloudera vice versa.
sample links :
link1
link2
link3
Initially I thought Spark would be faster than anything because of their in-memory execution. after reading some articles I got Somehow existing Hive also getting improvised with new concepts like Tez, ORC, LLAP etc.
Currently running with PL/SQL Oracle and migrating to big data since volumes are getting increased. My requirements are kind of ETL batch processing and included data details involved in every weekly batch runs. Data will increase widely soon.
Input/lookup data are csv/text formats and updating into tables
Two input tables which has 5 million rows and 30 columns
30 look up tables used to generate each column of output table which contains around 10 million rows and 220 columns.
Multiple joins involved like inner and left outer since many look up tables used.
Kindly please advise which one of below method I should choose for better performance with readability and easy to include minor updates on columns for future production deployment.
Method 1:
Hive on Tez with ORC tables
Python UDF thru TRANSFORM option
Joins with performance tuning like map join
Method 2:
SparkSQL with Parquet format which is converting from text/csv
Scala for UDF
Hope we can perform multiple inner and left outer join in Spark
The best way to implement the solution to your problem as below.
To load the data into the table the spark looks good option to me. You can read the tables from the hive metastore and perform the incremental updates using some kind of windowing functions and register them in hive. While ingesting as data is populated from various lookup table, you are able to write the code in programatical way in scala.
But at the end of the day, there need to be a query engine that is very easy to use. As your spark program register the table with hive, you can use hive.
Hive support three execution engines
Spark
Tez
Mapreduce
Tez is matured, spark is evolving with various commits from Facebook and community.
Business can understand hive very easily as a query engine as it is much more matured in the industry.
In short use spark to process the data for daily processing and register them with hive.
Create business users in hive.
I am new to Scala, and i have to use Scala and Spark's SQL, Mllib and GraphX in order to perform some analysis on huge data set. The analyses i want to do are:
Customer life cycle Value (CLV)
Centrality measures (degree, Eigenvector, edge-betweenness,
closeness) The data is in a CSV file (60GB (3 years transnational data))
located in Hadoop cluster.
My question is about the optimal approach to access the data and perform the above calculations?
Should i load the data from the CSV file into dataframe and work on
the dataframe? or
Should i load the data from the CSV file and convert it into RDD and
then work on the RDD? or
Are there any other approach to access the data and perform the analyses?
Thank you so much in advance for your help..
Dataframe gives you sql like syntax to work with the data where as RDD gives Scala collection like methods for data manipulation.
One extra benefit with Dataframes is underlying spark system will optimise your queries just like sql query optimisation. This is not available in case of RDD's.
As you are new to Scala its highly recommended to use Dataframes API initially and then Pick up RDD API later based on requirement.
You can use Databricks CSV reader api, which is easy to use and returns DataFrame. It automatically infer data types. If you pass the file with header it can automatically use that as Schema, otherwise you can construct schema using StructType.
https://github.com/databricks/spark-csv
Update:
If you are using Spark 2.0 Version , by default it support CSV datasource, please see the below link.
https://spark.apache.org/releases/spark-release-2-0-0.html#new-features
See this link for how to use.
https://github.com/databricks/spark-csv/issues/367