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new 7a223811 BLOG - Apache Cassandra 5.0 Features: Unified Compaction
Strategy
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commit 7a223811c2974e9d5a51d1ceb9ee6ee883252f18
Author: Diogenese Topper <[email protected]>
AuthorDate: Tue Oct 24 11:52:05 2023 -0700
BLOG - Apache Cassandra 5.0 Features: Unified Compaction Strategy
patch by Diogenese Topper, Lorina Poland; reviewed by Mick Semb Wever for
CASSANDRA-18957
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- Replace post tile, date, description and link to you post.
////
+//start card
+[openblock,card shadow relative test]
+----
+[openblock,card-header]
+------
+[discrete]
+=== Apache Cassandra 5.0 Features: Unified Compaction Strategy
+[discrete]
+==== October 24, 2023
+------
+[openblock,card-content]
+------
+Unified Compaction Strategy optimizes Apache Cassandra data compaction,
adapting to diverse workloads for improved performance.
+[openblock,card-btn card-btn--blog]
+--------
+[.btn.btn--alt]
+xref:blog/Apache-Cassandra-5.0-Features-Unified-Compaction-Strategy.adoc[Read
More]
+--------
+
+------
+----
+//end card
+
//start card
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+= Apache Cassandra 5.0 Features: Unified Compaction Strategy
+:page-layout: single-post
+:page-role: blog-post
+:page-post-date: October 27, 2023
+:page-post-author: Lorina Poland
+:description:
+:keywords:
+
+__Apache Cassandra 5.0 is the project’s major release for 2023, and it
promises some of the biggest changes for Cassandra to-date. After more than a
decade of engineering work dedicated to stabilizing and building Cassandra as a
distributed database, we now look forward to introducing a host of exciting
features and enhancements that empower users to take their data-driven
applications to the next level - including machine learning and artificial
intelligence.__
+
+__This blog series aims to give a deeper dive into some of the key features of
Cassandra 5.0.__
+
+== Introduction
+
+Compaction is an essential process in Apache Cassandra® that merges and
optimizes data on disk to improve read performance and free disk space. Until
now, users had to choose between different compaction strategies upfront, each
with its own advantages and drawbacks. Switching later is very difficult. To
address these challenges, the Unified Compaction Strategy (UCS) has been
introduced as a powerful and adaptive compaction solution.
+
+In this blog post, we will dive into the details of the UCS, demonstrate its
usage, and compare it to existing compaction strategies in Cassandra.
+
+== The Unified Compaction Strategy
+
+Unified Compaction Strategy (UCS), is a cutting-edge compaction strategy that
harmoniously blends the benefits of tiered and leveled compaction strategies
while adding sharding capabilities. UCS enables seamless reconfiguration at any
time and serves as the foundation for future compaction improvements, including
automatic adaptation to various workloads. By leveraging the similarities
between tiered and leveled compactions and utilizing the concept of "density"
instead of "size", UCS cr [...]
+
+UCS offers users the flexibility to choose between leveled and/or tiered
strategies based on their unique requirements by adjusting the fanout factor
and minimum SSTable size parameters. This tuning capability allows optimal
trade-offs between read amplification (RA) and write amplification (WA) to be
made, catering to different workloads and performance demands. Moreover, UCS
supports the customization of fanout factors for each level, empowering users
to define mixed strategies that ad [...]
+
+== Using the Unified Compaction Strategy
+
+To use UCS even in a currently running cluster, you can update your table's
compaction configuration as follows:
+
+`ALTER TABLE your_table WITH compaction = { 'class':
'UnifiedCompactionStrategy', 'scaling_parameters': 'T8, T4, N, L4' };`
+
+In this example, the scaling_parameters option specifies the fan factor and
compaction method for each level of the hierarchy. You can customize these
parameters to suit your specific workload requirements. If the list is shorter
than the number of levels, the last value is repeated for all higher levels.
+
+Remember that higher values of the scaling parameter improve write
amplification (WA) at the expense of read amplification (RA), while lower
values improve RA at the expense of WA. You can tailor the scaling parameters
to your specific workload requirements to optimize the performance of your
Apache Cassandra deployment.
+
+The full list of new parameters are listed here:
+
+:===
+Parameter:Explanation
+
+scaling_parameters
+Specifies per-level scaling parameters, used to define the behavior for all
levels of the hierarchy. Determines whether leveled, tiered, or mixed
compaction is used. Default value is T4.
+
+target_sstable_size
+Target size for SSTables. Balances streaming and repair efficiency with memory
pressure. Default value is 1 GiB.
+
+base_shard_count
+Minimum number of shards for levels with the smallest density. Affects L0
SSTables and write throughput. Default value is 4 (1 for system tables, or when
multiple data locations are defined).
+
+expired_sstable_check_frequency_seconds
+Frequency of checking for expired SSTables. Default value is 10 minutes.
+:===
+
+=== Comparing Compaction Strategies
+
+To better understand the benefits of UCS, let's compare it to existing
compaction strategies in Apache Cassandra.
+
+:===
+Compaction Strategy:Best Suited For:Read Amplification:Write
Amplification:Space Overhead:Complexity:Concurrency
+
+STCS
+Write-heavy, non-time series workloads
+High
+Low
+High
+Moderate
+Moderate
+
+LCS
+Read-heavy workloads, wide partition non-TS
+Low
+Moderate
+Moderate
+High
+Low
+
+TWCS
+Time series workloads
+Moderate
+Moderate
+Moderate
+Moderate
+Moderate
+
+UCS
+Wide range of workloads (adapts based on config)
+Adaptive
+Adaptive
+Adaptive
+Low
+High
+:===
+
+As this table shows, UCS adapts to different workloads, offering better
read/write amplification tradeoffs and concurrency while maintaining a lower
complexity level.
+Conclusion
+The Unified Compaction Strategy in Apache Cassandra provides an adaptive and
flexible solution to the existing challenges of compaction. It simplifies the
decision-making process for users while offering better performance and
resource utilization. With UCS, users no longer have to worry about suboptimal
compaction choices and can instead focus on their application's core
functionality.
+
+As the development of UCS continues, the roadmap aims to make the strategy
even more adaptive, relieving the user of the hard task of choosing suitable
compaction choices, and making Apache Cassandra an even more powerful solution
for database development.
+
+
+== Learn More About Apache Cassandra
+
+As we get closer to the General Availability of Cassandra 5.0, there are a
host of ways to get more involved in the community and follow project
developments:
+
+https://events.linuxfoundation.org/cassandra-summit/[Cassandra Summit + Code
AI^] is taking place Dec. 12-13 in San Jose, CA. Cassandra Summit is THE
gathering place for Apache Cassandra data practitioners, developers, engineers
and enthusiasts, and it’s where we’ll be diving deeper into Cassandra 5.0
features.
https://events.linuxfoundation.org/cassandra-summit/program/cfp/#overview[Submit
a talk^] for the NEW AI Track at Cassandra Summit; CFP closes Monday, October
26 at 9:00 AM PDT (UTC-7).
+
+For more information about Apache Cassandra or to join the community
discussion, you can join us on these channels:
+
+* https://cassandra.apache.org/_/index.html[Apache Cassandra Website]
+* https://the-asf.slack.com/ssb/redirect[ASF Slack^]
+* https://www.youtube.com/@PlanetCassandra[Planet Cassandra Youtube^]
+* https://www.meetup.com/cassandra-global/[Planet Cassandra Global Meetup
Group^]
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