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What happens when I "select * from ColumnFamily" in a given Cassandra Cluster


What happens when I "select * from ColumnFamily" in a given Cassandra Cluster

By : user3099990
Date : January 11 2021, 05:14 PM
I wish this help you No, that's really a very bad way to pull data. Cassandra shines when it fetches the data by at least partition key (that identifies a server that holds the actual data). When you are doing the select * from table, request is sent to coordinating node, that will need to pull all data from all servers and send via that coordinating node, overloading it, and most probably lead to the timeout if you have enough data in the cluster.
If you really need to perform full fetch of the data from cluster, it's better to use something like Spark Cassandra Connector that read data by token ranges, fetching the data directly from nodes that are holding the data, and doing this in parallel. You can of course implement the token range scan in Java driver, something like this, but it will require more work on your side, comparing to use of Spark.
code :


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cassandra copy data from one columnfamily to another columnfamily

cassandra copy data from one columnfamily to another columnfamily


By : Pepito_Alfred
Date : March 29 2020, 07:55 AM
hop of those help? Depending on the cassandra version you can use the copy cql command. To use that you need a cql client like the one that is distributted with cassandra.
First you have to copy the columnfamily A1 to a CSV file using:
code :
COPY K1.A1 (column1, column2,...) TO 'temp.csv';
COPY K1.A2 (column1, column2,...) FROM 'temp.csv';
Cassandra | CQL | show unconfigured columnfamily error with SELECT QUERY

Cassandra | CQL | show unconfigured columnfamily error with SELECT QUERY


By : user3367215
Date : March 29 2020, 07:55 AM
wish helps you typo?: CF is created as inlucde_authors but you request include_authors. Read carefully: inLUCde <-> inCLUde
Google compute Engine "Click to Deploy" allows only one cassandra cluster

Google compute Engine "Click to Deploy" allows only one cassandra cluster


By : user3447785
Date : March 29 2020, 07:55 AM
I wish this help you This is a known limitation with the current version of Click to Deploy. We are working on an update that will allow multiple deployments in a single project. To @chrispomeroy's point, a current workaround is to create another project and deploy your next cluster.
Getting PK columns from ColumnFamily columnFamily, ByteBuffer key Cassandra triggers

Getting PK columns from ColumnFamily columnFamily, ByteBuffer key Cassandra triggers


By : Steven Murphy
Date : March 29 2020, 07:55 AM
To fix this issue not sure if this what you mean, but you can get the name of the partition keys from columnFamily.partitionKeyColumns() the ColumnDefinition's have a name field thats readable. There may be more than one depending on schema
https://github.com/apache/cassandra/blob/cassandra-2.1/src/java/org/apache/cassandra/config/CFMetaData.java#L797
How to copy a columnfamily from one cassandra cluster to another?

How to copy a columnfamily from one cassandra cluster to another?


By : Jeric Millena
Date : March 29 2020, 07:55 AM
seems to work fine Take a snapshot on your existing cluster and use the bulk-loader on the target cluster, no need for Spark (although you could do it that way).
Here are the docs on the procedure, but I'll provide a high level overview of what you need to do.
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