There is a lot of information about kappa architecture in the internet and after going through some of the conceptual aspects I am trying to drill down to something more concrete. As I main source I used this website.
Let's imaging you want to implement a kappa architecture involving the following tech stack:
Apache Kafka
Apache Spark
Apache Superset
Now imagine the application you want to build do data-analytics against has a PostgreSQL database. Of course you can easily directly connect apache superset with the PostgresSQL database and create charts.
But now you want to see how you would do this with a kappa architecture and you add kafka and spark.
You can emit events to kafka and you can read such events in apache spark. Kafka will retain messages for topcis a certain period as pointed out in the answers to this quesition. When I read about connecting superset with spark in the docs it says hive should be used as a connector (also the project websites states the tool is unsupported, and if you look at this issue on pyhive then you find impyla could be an alternative). But apache hive is a completely different project for a storage system. So how would this connection work?
Assuming you have kafka nodes running (with zookeper obviously) and also have spark running and then you connect apache superset through this hive connector with spark.
How can you write queries against the data that is in kafka (which is in fact the live data)?
On spark side itself you can easily write a scala program that reads data from kafka and does something with it but how can you achieve this from apache superset?
Or is this not the intended way of connecting the things?
If I understood your question, you'd need to use Spark Structured Streaming to register a streaming SQL table into the Hive metastore, which could be queried from Superset from the Spark Thiftserver.
Hive itself doesn't store any of the data. Hive also has a built-in Kafka query handler, so Spark isn't completely necessary.
But, Hive/Spark isn't the only option. You could use Spark to write to HDFS/S3 and have Presto query that from Superset.
Or you can remove Spark and use Kafka Connect write to any other thing that a dashboarding tool (Tableau is another popular one) can support - JDBC database (i.e. Postgres), Mongo, Cassandra, etc. Then you'd just refresh the panels to run a new query.
Related
I have a requirement to implement the solution for below usecase.
Currently Applications are storing data into Postgres database but Postgres database is facing storage issue. So the plan is to move the data from postgres to Hadoop with near realtime data in hadoop. So we thought of below solution .
Write Kafka producer application to listen to postgres tables and capture changing data and write to Kafka Topic .
Write a Kafka sink application to read from kafka topic and write to hive tables(parquet -- external tables -- partitioned and non partitioned) . So for non partitioned tables if we want to apply updates/deletes then we need to touch the whole table in spark code right? which will lead to performance degrade for every record getting from kafka topic . We have already developed sqoop incremental job which runs for every 5 minutes to do the same. But client needs real time data in hadoop so kafka+spark processing came into discussion .
Could you provide pro's and con's for step2 comparing to sqoop incremental.
please share code snippets/links if any which helps my thought process.
Getting data into Kafka is easy - use Debezium.
For getting it out...
I wouldn't use Hive at all for this. Real time data (depending on on the volume of the data, obviously) results in tiny files in HDFS. Subsequently, Hive queries become slower and slower over time.
Hive is not a replacement for Postgres. In fact, the Hive metastore requires a relational database still, such as Postgres.
I also wouldn't use Spark. You have to write code when ingesting Kafka topics into queryable formats is already a solved problem with other tools.
Popular options include Apache Pinot, Druid, or Apache Iceberg storage with Presto (some of which may overlap with HDFS storage, but will be much, much faster than Hive to query). Only the third option requires writing Kafka consumer code; the other two have native Kafka ingestion.
And even still, if you're stuck with HDFS, Kafka Connect framework comes with Kafka. There's an HDFS Sink plugin, written by Confluent, which supports Hive integration.
Can someone let me know if its possible to to Spark structured streaming from a JDBC source? E.g SQL DB or any RDBMS.
I have looked at a few similar questions on SO, e.g
Spark streaming jdbc read the stream as and when data comes - Data source jdbc does not support streamed reading
jdbc source and spark structured streaming
However, I would like to know if its officially supported on Apache Spark?
If there is any sample code that would be helpful.
Thanks
No, there is no such built-in support in Spark Structured Streaming. The main reason is that most of databases doesn't provided an unified interface for obtaining the changes.
It's possible to get changes from some databases using archive logs, write-ahead logs, etc. But it's database-specific. For many databases the popular choice is Debezium that can read such logs and push list of changes into a Kafka, or something similar, from which it could be consumed by Spark.
I am on a project now architecting this using CDC Shareplex from ORACLE and writing to KAFKA and then using Spark Structured Streaming with KAFKA integration and MERGE on delta format on HDFS.
Ie that is the way to do it if not using Debezium. You can use change logs for base tables or materialized views to feed CDC.
So direct JDBC is not possible.
I have a requirement to build aggregations on the data that we receive to our Apache Kafka...
I am little bit lost which technlogical path to follow...
It seems people see the standard way, a constellation of Apache Kafka <-> Apache Spark <-> Solr
Bitnami Data Platform
I can't find concrete examples how this actually functions, but I am also asking myself would any solution von
Apache Kafka <-> Kafka Connect Solr <-> Solr
would not do the trick becasue solr supports aggregations also...
Solr Aggregation
but I saw some code snippets that aggregate the Data in Spark and write under special index to Solr.....
Also probably aggregation mit Kafka <-> Kafka Connect Solr <-> Solr will only function for only one Topic from Kafka, so if I have to combine the data from 2 or more, different Topics and aggregate, then Kafka, Spark, Solr is way to go.... (or this viable at all)
So as you may read, I am little bit confused, so I like to ask here, how are you approching this problem with your real life solutions....
Thx for answers...
Spark can of course join multiple topics. So can Flink, or Kafka Streams/KsqlDB. Spark or Flink just happen to be able to also write their data to external sources, such as Solr, rather than exclusively back into a new Kafka topic. The "downside" is that you need to maintain a scheduler exclusively for those, as compared to running a cluster of standalone Kafka Connect or Kafka Streams JAR applications. If you're using kubernetes, then that could be used for all of above (maybe not Flink... Haven't tried)
Kafka Connect can consume multiple topics and, depending on the connector configuration, might write to one or many Solr collections.
I Have a cluster of 4 nodes, I installed Hadoop+ Spark (GraphX)...
Now I have to process a big RDF dataset,
my question is : Can I install Virtuoso on the cluster so to store this RDF datasets and to be able to execute SPARQL distributed queries?
To the best of your knowledge, I need a web endpoint to allow users putting their SPARQL Queries.
in other words: is Virtuoso a good solution that works in a hadoop cluster, and can use SPARK to execute the distributed queries?
The Apache Spark website indicates that Spark SQL can be used to query across JDBC and JSON data sources --
DataFrames and SQL provide a common way to access a variety of data sources, including Hive, Avro, Parquet, ORC, JSON, and JDBC. You can even join data across these sources.
Virtuoso (both Open Source and Enterprise Edition) can deliver SPARQL results as JSON serializations, so that is an option.
We (OpenLink Software) also provide JDBC drivers for Virtuoso (again, both Open Source and Enterprise Edition), so that is also an option.
We are not Apache Spark experts, so we cannot provide much guidance for getting these working beyond assisting with Virtuoso JDBC URLs and/or retrieving SPARQL query results in JSON serialization.
In the other direction, Virtuoso (Enterprise Edition; not Open Source Edition) can be used to query against external ODBC data sources, and there are ODBC drivers available for Hadoop/SPARK data sources, so this is also an option.
We are not Apache Spark experts, so we cannot provide much guidance for getting their drivers working, but once you have a functional ODBC DSN on the Virtuoso host, we can assist in getting Virtuoso connected to and querying against it.
Are you seeking to upload RDF datasets from your Hadoop Cluster using SPARK jobs? If so, you can use JDBC and the connection to Virtuoso.
I stumbled upon a Dzone doc that covers SPARK and JDBC which once understood you can apply to Virtuoso via its ability to process SPARQL queries via SQL connections.
I hope that helps, if not, we can discuss further.
Currently we are building a reporting platform as a data store we used Shark. Since the development of Shark is stopped so we are in the phase of evaluating Spark SQL. Based on the use cases we have we had few questions.
1) We have data from various sources( MySQL, Oracle, Cassandra, Mongo). We would like to know how can we get this data into Spark SQL? Does there exist any utility which we can use? Does this utility support continuous refresh of data (sync of new add/update/delete on data store to Spark SQL?
2) Is the a way to create multiple database in Spark SQL?
3) For Reporting UI we use Jasper, we would like to connect from Jasper to Spark SQL. When we did our initial search we got to know currently there is no support for consumer to connect Spark SQL through JDBC, but in future releases you would like the add the same. We would like to know by when Spark SQL would have a stable release which would have JDBC Support? Meanwhile we took the source code from https://github.com/amplab/shark/tree/sparkSql but we had some difficulty in setting it up locally and evaluating it . It would be great if you can help us with setup instructions.(I can share the issue we are facing please let me know where can I post the error logs)
4) We would also require a SQL prompt where we can execute queries, currently Spark Shell provides SCALA prompt where SCALA code can be executed, from SCALA code we can fire SQL queries. Like Shark we would like to have SQL prompt in Spark SQL. When we did our search we found that in future release of Spark this would be added. It would be great if you can tell us which release of Spark would address the same.
as for
3) Spark 1.1 provides better support for SparkSQL ThriftServer interface, which you may want to use for JDBC interfacing. Hive JDBC clients that support v. 0.12.0 are able to connect and interface with such server.
4) Spark 1.1 also provides a SparkSQL CLI interface that can be used for entering queries. In the same fashion that Hive CLI or Impala Shell.
Please, provide more details about what you are trying to achieve for 1 and 2.
I can answer (1):
Apache Sqoop was made specifically to solve this problem for the relational databases. The tool was made for HDFS, HBase, and Hive -- as such it can be used to make data available to Spark, via HDFS and the Hive metastore.
http://sqoop.apache.org/
I believe Cassandra is available to SparkContext via this connector from DataStax: https://github.com/datastax/spark-cassandra-connector -- which I have never used.
I'm not aware of any connector for MongoDB.
1) We have data from various sources( MySQL, Oracle, Cassandra, Mongo)
You have to use different driver for each case. For cassandra there is datastax driver (but i encountered some compatibility problems with SparkSQL). For any SQL system you can use JdbcRDD. The usage is straightforward, look at the scala example:
test("basic functionality") {
sc = new SparkContext("local", "test")
val rdd = new JdbcRDD(
sc,
() => { DriverManager.getConnection("jdbc:derby:target/JdbcRDDSuiteDb") },
"SELECT DATA FROM FOO WHERE ? <= ID AND ID <= ?",
1, 100, 3,
(r: ResultSet) => { r.getInt(1) } ).cache()
assert(rdd.count === 100)
assert(rdd.reduce(_+_) === 10100)
}
But notion that it's just an RDD, so you should work with this data through map-reduce api, not in SQLContext.
Does there exist any utility which we can use?
There is Apache Sqoop project but it's in active development state. The current stable version even doesn't save files in parquet format.
Spark SQL is a capability of the Spark framework. It shouldn't be compared to Shark because Shark is a service. (Recall that with Shark, you run a ThriftServer that you can then connect to from your Thrift app or even ODBC.)
Can you elaborate on what you mean by "get this data into Spark SQL"?
There are a couple of Spark - MongoDB connectors:
- the mongodb connector for hadoop (which doesn't actually need Hadoop at all!) https://databricks.com/blog/2015/03/20/using-mongodb-with-spark.html
the Stratio mongodb connector https://github.com/Stratio/spark-mongodb
If your data is huge and need to perform a lot of transformations then Spark SQL can be used for ETL purpose, else presto could solve all your problems. Addressing your queries one by one:
As your data is in MySQL, Oracle, Cassandra, Mongo all these can be integrated in Presto as it has connectors https://prestodb.github.io/docs/current/connector.html for all these databases.
Once you install Presto in cluster mode you can query all these databases together in one platform, which also provides to join a table from Cassandra and other tables from Mongo, this flexibility is unparalleled.
Presto can be used to connect to Apache Superset https://superset.incubator.apache.org/ which is open source and provides all sets Dashboarding. Also Presto can be connected to Tableau.
You can install MySQL workbench with presto connecting details which helps in providing a UI for all your databases at one place.