Apache Cassandra

Clients and Transports

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Hi Folks!I’m Nate @zznate

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API ManagementAPI AnalyticsAPI Tools

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Clients and transportsfor Cassandra

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But first... some questions

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But first: Architectural stuff

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Cassandra:“Sparsely Columnar”

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An RDBMS table

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An RDBMS table

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Cassandra Style

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Cassandra Style

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Cassandra data modelling

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Four common patternsSimple object to simple rowSparse object to rowsMaterialized viewManual index

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simple objects to simple row

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“static” column family

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Sparse Objects

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“dynamic” column family

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Materialized Views

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Materialized view

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Regardless of the approached used, there are four overall goals

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1. Denormalize2. Eliminate seeks3. Design for read4. Optimiza for blind writes

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Now... let’s talk about protocols

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Thrift

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ThriftRPC-Based

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ThriftRPC-BasedMature Apache Project

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ThriftRPC-BasedMature Apache ProjectSupports lots of languages

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ThriftRPC-BasedMature Apache ProjectSupports lots of languagesExtensible!

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CQL

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CQLWell defined protocol

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CQLWell defined protocolSupports Compression

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CQLWell defined protocolSupports CompressionNetty/NIO-based

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Storage Mechanics(but quickly)

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get_slice

Workhorse of Cassandra selection methods

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get_slice: key

The row key

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get_slice: ColumnParent

The column family (a.k.a table)

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get_slice: SlicePredicate

defines the column range, or specifically named columns

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get_slice:ConsistencyLevel

The level of consistency we want for this read

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Obtuse at first glance, but nothing is hidden

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So...

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But one person’s abstraction leakage is another’s preffered model

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How closely do you want to interact with the underlying storage engine?

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Client APIs

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Benefits of thrift

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Benefits of thriftMature selection of clients

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Benefits of thriftMature selection of clientsMultiple languages

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Benefits of thriftMature selection of clientsMultiple languagesWell documented

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Benefits of thriftMature selection of clientsMultiple languagesWell documentedCan be used in other places

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Drawbacks of thrift

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Drawbacks of thriftSeveral objects are required for any request

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Drawbacks of thriftSeveral objects are required for any requestClients differs in implementation

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Drawbacks of thriftSeveral objects are required for any requestClients differs in implementationUpstream dependency issues

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Drawbacks of thriftSeveral objects are required for any requestClients differs in implementationUpstream dependency issuesSchema changes and cluster health done pro-actively

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Benefits of cql api

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Benefits of cql apiStored procedures

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Benefits of cql apiStored proceduresCommon operations are straight forward

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Benefits of cql apiStored proceduresCommon operations are straight forward Cluster health and schema change push-back

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Benefits of cql apiStored proceduresCommon operations are straight forward Cluster health and schema change push-backAwesome client available

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Drawbacks of CQL apis

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Drawbacks of CQL apisStill have idiomatic clients

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Drawbacks of CQL apisStill have idiomatic clientsStill a binary protocol

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Drawbacks of CQL apisStill have idiomatic clientsStill a binary protocolDefault storage model emposes substantial restrictions** see gotchas section later

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Considerations for your app

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Stick with Thrift if...

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Heavy update workloads

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Large, dynamic batch insertions

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Hadoop integration(CASSANDRA-4421)

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Commonly deal with very wide rows(CASSANDRA-4176)

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CASSANDRA-4176:“Pick your shard keys carefully”

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Consider CQL if...

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Static column family model:Take advantage of stored procedures for common reads

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Despite the shard key jab, CQL makes good use of the storage model

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You can replace some custom serialization with collections

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Integration with JDBC and/or BI tools

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Wire efficient:Does not return timestamp or TTL by default

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Larger, potentially more transient evironments

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But CQL is - new- an abstraction

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In some cases, CQL might not do what you think

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Most common CQL pitfalls

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Collections can only be retrieved in their entirety

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Can’t mix static and dynamic data in a column family

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“keys only” range slices don’t work(CASSANDRA-4536)

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Range ghosts will not be returned

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Batch inserts are clunky(CASSANDRA-4693)

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With non-compact storage the whole row must be read every time.

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The take away is that you have options. Particularly good ones for Java.

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BUT

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there is a larger, more fundamental problem to discuss

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“If [they] think that CQL is the answer to usability then I just won. We at least know where our problems are.”- 10gen exec.

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The market has spoken and we missed the boat.

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POST /endpoint {json}

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A Cassandra-MVP actually maintains a REST front-end

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So we’ve taken this and gone further

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What if...

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Coming soon...Intravert. Vert.x+Cassandra.ASF-licensed.Driven by real-world requirements.

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