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Couchbase vs Scylla: What are the differences?
Introduction
In this article, we will discuss the key differences between Couchbase and Scylla, two popular database systems. Both Couchbase and Scylla offer high performance and scalability, but they have distinct features and use cases that set them apart.
Data Model: One major difference between Couchbase and Scylla lies in their data models. Couchbase is a document-oriented database that stores data in JSON-like documents. This flexibility allows for dynamic schemas and easy handling of complex data structures. On the other hand, Scylla is a column-oriented database that stores data in tables with rows and columns resembling relational databases. This structure provides efficient storage and retrieval for large quantities of data with a predefined schema.
Consistency Model: Couchbase and Scylla also differ in their consistency models. Couchbase offers strong consistency, ensuring that all clients see the same data at the same time. This is important for applications where data integrity is critical. In contrast, Scylla provides eventual consistency, where updates to data may take some time to propagate to all replicas. This makes Scylla suitable for systems that prioritize high availability and low latency over strict consistency.
Data Distribution: Another key difference is how Couchbase and Scylla distribute data across their clusters. Couchbase employs a distributed hash table (DHT) approach, commonly known as consistent hashing. It evenly distributes data across multiple nodes in the cluster, providing automatic sharding and load balancing. On the other hand, Scylla uses a partitioned row store (Paxos) algorithm to distribute data. This algorithm ensures fault tolerance and linear scalability while maintaining data locality for optimal performance.
Query Language: Couchbase and Scylla also vary in their query languages. Couchbase uses N1QL (pronounced as "nickel"), a SQL-like query language that provides easy ad hoc querying and analytics capabilities. N1QL supports complex joins, filtering, and aggregation for flexible data retrieval. In contrast, Scylla uses CQL (Cassandra Query Language), which is similar to SQL but designed specifically for Cassandra and Scylla. CQL offers a simplified query syntax and supports basic CRUD operations.
Secondary Indexing: Couchbase and Scylla handle secondary indexing differently. In Couchbase, secondary indexes are automatically maintained by the database, allowing for efficient querying on non-primary key attributes. This makes it easy to add, update, or remove indexes without impacting the application's performance. Scylla, however, does not natively support secondary indexes. Instead, it encourages denormalization and materialized views to optimize queries for different use cases.
Storage Engine: Lastly, Couchbase and Scylla use different storage engines. Couchbase utilizes a memory-centric storage engine called Memory-First Architecture (MFA). This engine prioritizes data in-memory for fast access and leverages disk storage for persistence and durability. Scylla, on the other hand, uses its own storage engine called ScyllaDB. It is built from scratch, utilizing the Seastar framework and leveraging the power of C++ to deliver high performance and low latency.
In Summary, Couchbase and Scylla differ in terms of their data models, consistency models, data distribution methods, query languages, secondary indexing approaches, and storage engines. These differences stem from their design philosophies, making them suitable for different use cases and workloads.
We Have thousands of .pdf docs generated from the same form but with lots of variability. We need to extract data from open text and more important - from tables inside the docs. The output of Couchbase/Mongo will be one row per document for backend processing. ADOBE renders the tables in an unusable form.
I prefer MongoDB due to own experience with migration of old archive of pdf and meta-data to a new “archive”. The biggest advantage is speed of filters output - a new archive is way faster and reliable then the old one - but also the the easy programming of MongoDB with many code snippets and examples available. I have no personal experience so far with Couchbase. From the architecture point of view both options are OK - go for the one you like.
I would like to suggest MongoDB or ArangoDB (can't choose both, so ArangoDB). MongoDB is more mature, but ArangoDB is more interesting if you will need to bring graph database ideas to solution. For example if some data or some documents are interlinked, then probably ArangoDB is a best solution.
To process tables we used Abbyy software stack. It's great on table extraction.
If you can select text with mouse drag in PDF. Use pdftotext it is fast! You can install it on server with command "apt-get install poppler-utils". Use it like "pdftotext -layout /path-to-your-file". In same folder it will make text file with line by line content. There is few classes on git stacks that you can use, also.
The problem I have is - we need to process & change(update/insert) 55M Data every 2 min and this updated data to be available for Rest API for Filtering / Selection. Response time for Rest API should be less than 1 sec.
The most important factors for me are processing and storing time of 2 min. There need to be 2 views of Data One is for Selection & 2. Changed data.
Scylla can handle 1M/s events with a simple data model quite easily. The api to query is CQL, we have REST api but that's for control/monitoring
Cassandra is quite capable of the task, in a highly available way, given appropriate scaling of the system. Remember that updates are only inserts, and that efficient retrieval is only by key (which can be a complex key). Talking of keys, make sure that the keys are well distributed.
By 55M do you mean 55 million entity changes per 2 minutes? It is relatively high, means almost 460k per second. If I had to choose between Scylla or Cassandra, I would opt for Scylla as it is promising better performance for simple operations. However, maybe it would be worth to consider yet another alternative technology. Take into consideration required consistency, reliability and high availability and you may realize that there are more suitable once. Rest API should not be the main driver, because you can always develop the API yourself, if not supported by given technology.
i love syclla for pet projects however it's license which is based on server model is an issue. thus i recommend cassandra
The Gentlent Tech Team made lots of updates within the past year. The biggest one being our database:
We decided to migrate our #PostgreSQL -based database systems to a custom implementation of #Cassandra . This allows us to integrate our product data perfectly in a system that just makes sense. High availability and scalability are supported out of the box.
We implemented our first large scale EPR application from naologic.com using CouchDB .
Very fast, replication works great, doesn't consume much RAM, queries are blazing fast but we found a problem: the queries were very hard to write, it took a long time to figure out the API, we had to go and write our own @nodejs library to make it work properly.
It lost most of its support. Since then, we migrated to Couchbase and the learning curve was steep but all worth it. Memcached indexing out of the box, full text search works great.
Pros of Couchbase
- High performance18
- Flexible data model, easy scalability, extremely fast18
- Mobile app support9
- You can query it with Ansi-92 SQL7
- All nodes can be read/write6
- Equal nodes in cluster, allowing fast, flexible changes5
- Both a key-value store and document (JSON) db5
- Open source, community and enterprise editions5
- Automatic configuration of sharding4
- Local cache capability4
- Easy setup3
- Linearly scalable, useful to large number of tps3
- Easy cluster administration3
- Cross data center replication3
- SDKs in popular programming languages3
- Elasticsearch connector3
- Web based management, query and monitoring panel3
- Map reduce views2
- DBaaS available2
- NoSQL2
- Buckets, Scopes, Collections & Documents1
- FTS + SQL together1
Pros of ScyllaDB
- Replication2
- Fewer nodes1
- Distributed1
- Scale up1
- High availability1
- Written in C++1
- High performance1
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Cons of Couchbase
- Terrible query language3