Gegevens verwijderen in Azure Cosmos DB voor Apache Cassandra-tabellen uit Spark
VAN TOEPASSING OP: 
Cassandra
In dit artikel wordt beschreven hoe u gegevens verwijdert in Azure Cosmos DB voor Apache Cassandra-tabellen uit Spark.
API voor Cassandra-configuratie
Stel de onderstaande Spark-configuratie in uw notebookcluster in. Het is één keer activiteit.
//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
Notitie
Als u Spark 3.x gebruikt, hoeft u de Azure Cosmos DB-helper en verbindingsfactory niet te installeren. U moet ook gebruiken remoteConnectionsPerExecutor in plaats van connections_per_executor_max voor de Spark 3-connector (zie hierboven).
Waarschuwing
De Spark 3-voorbeelden die in dit artikel worden weergegeven, zijn getest met Spark-versie 3.2.1 en de bijbehorende Cassandra Spark-connector com.datastax.spark:spark-cassandra-connector-assembly_2.12:3.2.0. Latere versies van Spark en/of de Cassandra-connector werken mogelijk niet zoals verwacht.
Voorbeeldgegevensgenerator
We gebruiken dit codefragment om voorbeeldgegevens te genereren:
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
Rijen verwijderen die overeenkomen met een voorwaarde
//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
Uitvoer:
== 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
Alle rijen in de tabel verwijderen
//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
Uitvoer:
== 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
Alle rijen in de tabel verwijderen
//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)
Uitvoer:
==================
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
Specifieke kolommen verwijderen
//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)
Uitvoer:
==================
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
Volgende stappen
Als u aggregatie- en gegevenskopiebewerkingen wilt uitvoeren, raadpleegt u -