Ta bort data i Azure Cosmos DB för Apache Cassandra-tabeller från Spark

Artikel
08/15/2024

GÄLLER FÖR: Kassandra

Den här artikeln beskriver hur du tar bort data i Azure Cosmos DB för Apache Cassandra-tabeller från Spark.

API för Cassandra-konfiguration

Ställ in spark-konfigurationen nedan i notebook-klustret. Det är en engångsaktivitet.

//Connection-related
 spark.cassandra.connection.host  YOUR_ACCOUNT_NAME.cassandra.cosmosdb.azure.com  
 spark.cassandra.connection.port  10350  
 spark.cassandra.connection.ssl.enabled  true  
 spark.cassandra.auth.username  YOUR_ACCOUNT_NAME  
 spark.cassandra.auth.password  YOUR_ACCOUNT_KEY  
// if using Spark 2.x
// spark.cassandra.connection.factory  com.microsoft.azure.cosmosdb.cassandra.CosmosDbConnectionFactory  

//Throughput-related...adjust as needed
 spark.cassandra.output.batch.size.rows  1  
// spark.cassandra.connection.connections_per_executor_max  10   // Spark 2.x
 spark.cassandra.connection.remoteConnectionsPerExecutor  10   // Spark 3.x
 spark.cassandra.output.concurrent.writes  1000  
 spark.cassandra.concurrent.reads  512  
 spark.cassandra.output.batch.grouping.buffer.size  1000  
 spark.cassandra.connection.keep_alive_ms  600000000

Kommentar

Om du använder Spark 3.x behöver du inte installera Azure Cosmos DB-hjälpen och anslutningsfabriken. Du bör också använda remoteConnectionsPerExecutor i stället connections_per_executor_max för för Spark 3-anslutningsappen (se ovan).

Varning

Spark 3-exemplen som visas i den här artikeln har testats med Spark version 3.2.1 och motsvarande Cassandra Spark Connector com.datastax.spark:spark-cassandra-connector-assembly_2.12:3.2.0. Senare versioner av Spark och/eller Cassandra-anslutningsappen kanske inte fungerar som förväntat.

Exempeldatagenerator

Vi använder det här kodfragmentet för att generera exempeldata:

import org.apache.spark.sql.cassandra._
//Spark connector
import com.datastax.spark.connector._
import com.datastax.spark.connector.cql.CassandraConnector

//if using Spark 2.x, CosmosDB library for multiple retry
//import com.microsoft.azure.cosmosdb.cassandra

//Create dataframe
val booksDF = Seq(
   ("b00001", "Arthur Conan Doyle", "A study in scarlet", 1887,11.33),
   ("b00023", "Arthur Conan Doyle", "A sign of four", 1890,22.45),
   ("b01001", "Arthur Conan Doyle", "The adventures of Sherlock Holmes", 1892,19.83),
   ("b00501", "Arthur Conan Doyle", "The memoirs of Sherlock Holmes", 1893,14.22),
   ("b00300", "Arthur Conan Doyle", "The hounds of Baskerville", 1901,12.25)
).toDF("book_id", "book_author", "book_name", "book_pub_year","book_price")

//Persist
booksDF.write
  .mode("append")
  .format("org.apache.spark.sql.cassandra")
  .options(Map( "table" -> "books", "keyspace" -> "books_ks", "output.consistency.level" -> "ALL", "ttl" -> "10000000"))
  .save()

Dataframe-API

Ta bort rader som matchar ett villkor

//1) Create dataframe
val deleteBooksDF = spark
  .read
  .format("org.apache.spark.sql.cassandra")
  .options(Map( "table" -> "books", "keyspace" -> "books_ks"))
  .load
  .filter("book_id = 'b01001'")

//2) Review execution plan
deleteBooksDF.explain

//3) Review table data before execution
println("==================")
println("1) Before")
deleteBooksDF.show
println("==================")

//4) Delete selected records in dataframe
println("==================")
println("2a) Starting delete")

//Reuse connection for each partition
val cdbConnector = CassandraConnector(sc)
deleteBooksDF.foreachPartition((partition: Iterator[Row]) => {
  cdbConnector.withSessionDo(session =>
    partition.foreach{ book => 
        val delete = s"DELETE FROM books_ks.books where book_id='"+book.getString(0) +"';"
        session.execute(delete)
    })
})

println("2b) Completed delete")
println("==================")

//5) Review table data after delete operation
println("3) After")

spark
  .read
  .format("org.apache.spark.sql.cassandra")
  .options(Map( "table" -> "books", "keyspace" -> "books_ks"))
  .load
  .show

Utdata:

== Physical Plan ==
*(1) Filter (isnotnull(book_pub_year#486) && (book_pub_year#486 = 1887))
+- *(1) Scan org.apache.spark.sql.cassandra.CassandraSourceRelation@197cfae4 [book_id#482,book_author#483,book_name#484,book_price#485,book_pub_year#486] 
PushedFilters: [IsNotNull(book_pub_year), EqualTo(book_pub_year,1887)], 
ReadSchema: struct<book_id:string,book_author:string,book_name:string,book_price:float,book_pub_year:int>
==================
1) Before
+-------+------------------+------------------+----------+-------------+
|book_id|       book_author|         book_name|book_price|book_pub_year|
+-------+------------------+------------------+----------+-------------+
| b00001|Arthur Conan Doyle|A study in scarlet|     11.33|         1887|
+-------+------------------+------------------+----------+-------------+

==================
==================
2a) Starting delete
2b) Completed delete
==================
3) After
+-------+------------------+--------------------+----------+-------------+
|book_id|       book_author|           book_name|book_price|book_pub_year|
+-------+------------------+--------------------+----------+-------------+
| b00300|Arthur Conan Doyle|The hounds of Bas...|     12.25|         1901|
| b03999|Arthur Conan Doyle|The adventure of ...|      null|         1892|
| b00023|Arthur Conan Doyle|      A sign of four|     22.45|         1890|
| b00501|Arthur Conan Doyle|The memoirs of Sh...|     14.22|         1893|
| b01001|Arthur Conan Doyle|The adventures of...|     19.83|         1892|
| b02999|Arthur Conan Doyle|  A case of identity|      15.0|         1891|
+-------+------------------+--------------------+----------+-------------+

deleteBooksDF: org.apache.spark.sql.Dataset[org.apache.spark.sql.Row] = [book_id: string, book_author: string ... 3 more fields]
cdbConnector: com.datastax.spark.connector.cql.CassandraConnector = com.datastax.spark.connector.cql.CassandraConnector@187deb43

Ta bort alla rader i tabellen

//1) Create dataframe
val deleteBooksDF = spark
  .read
  .format("org.apache.spark.sql.cassandra")
  .options(Map( "table" -> "books", "keyspace" -> "books_ks"))
  .load

//2) Review execution plan
deleteBooksDF.explain

//3) Review table data before execution
println("==================")
println("1) Before")
deleteBooksDF.show
println("==================")

//4) Delete selected records in dataframe
println("==================")
println("2a) Starting delete")

//Reuse connection for each partition
val cdbConnector = CassandraConnector(sc)
deleteBooksDF.foreachPartition((partition: Iterator[Row]) => {
  cdbConnector.withSessionDo(session =>
    partition.foreach{ book => 
        val delete = s"DELETE FROM books_ks.books where book_id='"+book.getString(0) +"';"
        session.execute(delete)
    })
})

println("2b) Completed delete")
println("==================")

//5) Review table data after delete operation
println("3) After")

spark
  .read
  .format("org.apache.spark.sql.cassandra")
  .options(Map( "table" -> "books", "keyspace" -> "books_ks"))
  .load
  .show

Utdata:

== Physical Plan ==
*(1) Scan org.apache.spark.sql.cassandra.CassandraSourceRelation@495377d7 [book_id#565,book_author#566,book_name#567,book_price#568,book_pub_year#569] 
PushedFilters: [], 
ReadSchema: struct<book_id:string,book_author:string,book_name:string,book_price:float,book_pub_year:int>
==================
1) Before
+-------+------------------+--------------------+----------+-------------+
|book_id|       book_author|           book_name|book_price|book_pub_year|
+-------+------------------+--------------------+----------+-------------+
| b00300|Arthur Conan Doyle|The hounds of Bas...|     12.25|         1901|
| b03999|Arthur Conan Doyle|The adventure of ...|      null|         1892|
| b00023|Arthur Conan Doyle|      A sign of four|     22.45|         1890|
| b00501|Arthur Conan Doyle|The memoirs of Sh...|     14.22|         1893|
| b01001|Arthur Conan Doyle|The adventures of...|     19.83|         1892|
| b02999|Arthur Conan Doyle|  A case of identity|      15.0|         1891|
+-------+------------------+--------------------+----------+-------------+

==================
==================
2a) Starting delete
2b) Completed delete
==================
3) After
+-------+-----------+---------+----------+-------------+
|book_id|book_author|book_name|book_price|book_pub_year|
+-------+-----------+---------+----------+-------------+
+-------+-----------+---------+----------+-------------+

RDD-API

Ta bort alla rader i tabellen

//1) Create RDD with all rows
val deleteBooksRDD = 
    sc.cassandraTable("books_ks", "books")

//2) Review table data before execution
println("==================")
println("1) Before")
deleteBooksRDD.collect.foreach(println)
println("==================")

//3) Delete selected records in dataframe
println("==================")
println("2a) Starting delete")

/* Option 1: 
// Not supported currently
sc.cassandraTable("books_ks", "books")
  .where("book_pub_year = 1891")
  .deleteFromCassandra("books_ks", "books")
*/

//Option 2: CassandraConnector and CQL
//Reuse connection for each partition
val cdbConnector = CassandraConnector(sc)
deleteBooksRDD.foreachPartition(partition => {
    cdbConnector.withSessionDo(session =>
    partition.foreach{book => 
        val delete = s"DELETE FROM books_ks.books where book_id='"+ book.getString(0) +"';"
        session.execute(delete)
    }
   )
})

println("Completed delete")
println("==================")

println("2b) Completed delete")
println("==================")

//5) Review table data after delete operation
println("3) After")
sc.cassandraTable("books_ks", "books").collect.foreach(println)

Utdata:

==================
1) Before
CassandraRow{book_id: b00300, book_author: Arthur Conan Doyle, book_name: The hounds of Baskerville, book_price: 12.25, book_pub_year: 1901}
CassandraRow{book_id: b00001, book_author: Arthur Conan Doyle, book_name: A study in scarlet, book_price: 11.33, book_pub_year: 1887}
CassandraRow{book_id: b00023, book_author: Arthur Conan Doyle, book_name: A sign of four, book_price: 22.45, book_pub_year: 1890}
CassandraRow{book_id: b00501, book_author: Arthur Conan Doyle, book_name: The memoirs of Sherlock Holmes, book_price: 14.22, book_pub_year: 1893}
CassandraRow{book_id: b01001, book_author: Arthur Conan Doyle, book_name: The adventures of Sherlock Holmes, book_price: 19.83, book_pub_year: 1892}
==================
==================
2a) Starting delete
Completed delete
==================
2b) Completed delete
==================
3) After
deleteBooksRDD: com.datastax.spark.connector.rdd.CassandraTableScanRDD[com.datastax.spark.connector.CassandraRow] = CassandraTableScanRDD[126] at RDD at CassandraRDD.scala:19
cdbConnector: com.datastax.spark.connector.cql.CassandraConnector = com.datastax.spark.connector.cql.CassandraConnector@317927

Ta bort specifika kolumner

//1) Create RDD 
val deleteBooksRDD = 
    sc.cassandraTable("books_ks", "books")

//2) Review table data before execution
println("==================")
println("1) Before")
deleteBooksRDD.collect.foreach(println)
println("==================")

//3) Delete specific column values
println("==================")
println("2a) Starting delete of book price")

sc.cassandraTable("books_ks", "books")
  .deleteFromCassandra("books_ks", "books",SomeColumns("book_price"))

println("Completed delete")
println("==================")

println("2b) Completed delete")
println("==================")

//5) Review table data after delete operation
println("3) After")
sc.cassandraTable("books_ks", "books").take(4).foreach(println)

Utdata:

==================
1) Before
CassandraRow{book_id: b00300, book_author: Arthur Conan Doyle, book_name: The hounds of Baskerville, book_price: 20.0, book_pub_year: 1901}
CassandraRow{book_id: b00001, book_author: Arthur Conan Doyle, book_name: A study in scarlet, book_price: 23.0, book_pub_year: 1887}
CassandraRow{book_id: b00023, book_author: Arthur Conan Doyle, book_name: A sign of four, book_price: 11.0, book_pub_year: 1890}
CassandraRow{book_id: b00501, book_author: Arthur Conan Doyle, book_name: The memoirs of Sherlock Holmes, book_price: 5.0, book_pub_year: 1893}
CassandraRow{book_id: b01001, book_author: Arthur Conan Doyle, book_name: The adventures of Sherlock Holmes, book_price: 10.0, book_pub_year: 1892}
==================
==================
2a) Starting delete of book price
Completed delete
==================
2b) Completed delete
==================
3) After
CassandraRow{book_id: b00300, book_author: Arthur Conan Doyle, book_name: The hounds of Baskerville, book_price: null, book_pub_year: 1901}
CassandraRow{book_id: b00001, book_author: Arthur Conan Doyle, book_name: A study in scarlet, book_price: null, book_pub_year: 1887}
CassandraRow{book_id: b00023, book_author: Arthur Conan Doyle, book_name: A sign of four, book_price: null, book_pub_year: 1890}
CassandraRow{book_id: b00501, book_author: Arthur Conan Doyle, book_name: The memoirs of Sherlock Holmes, book_price: null, book_pub_year: 1893}
deleteBooksRDD: com.datastax.spark.connector.rdd.CassandraTableScanRDD[com.datastax.spark.connector.CassandraRow] = CassandraTableScanRDD[145] at RDD at CassandraRDD.scala:19

Nästa steg

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Dela via

Ta bort data i Azure Cosmos DB för Apache Cassandra-tabeller från Spark

API för Cassandra-konfiguration

Exempeldatagenerator

Dataframe-API

Ta bort rader som matchar ett villkor

Ta bort alla rader i tabellen

RDD-API

Ta bort alla rader i tabellen

Ta bort specifika kolumner

Nästa steg

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