Storage articles

Looking for something else? Check the categories of Storage:

Apache Avro Apache Cassandra Apache Hudi Apache Iceberg Apache Parquet Apache ZooKeeper Delta Lake Elasticsearch Embedded databases HDFS MySQL PostgreSQL Time series

If not, below you can find all articles belonging to Storage.

Edit log in HDFS

HDFS stores everything that happens on transaction log files. They're used during checkpoint and file system recovery. So, they take quite important place in HDFS architecture.

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States in HDFS

Replica and blocks are HDFS entities having more than 1 state in their whole lifecycle. Being aware of these states helps a lot to understand what happens when a new file is written.

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Replication in HDFS

HDFS is a fault-tolerant and resilient distributed file system. It wouldn't be possible without, among others, blocks replication.

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File operations in HDFS

Previous article presented theoretical information about HDFS files. This post deepens this topic.

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Files in HDFS

Files in HDFS are different from files from local file system. They're fault-tolerant, can be stored in different abstractions and are based on quite big blocks comparing to blocks in local file system.

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Introduction to HDFS

HDFS is one of most popular distributed file systems in our days. It changes from other older distributed file systems thanks to its reliability.

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Mapper in Cassandra Java API

Before writing some code in Apache Cassandra, we'll try to explore very interesting dependency - cassandra-driver-mapping.

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Cache in Apache Cassandra

I/O operations are slower than memory lookups. It's the reason why memory cache helps to improve performances, in Cassandra too.

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Collections in Apache Cassandra

One of interesting data types used in Apache Cassandra are collections. In our model we can freely use maps, sets or lists.

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Tables in Apache Cassandra

Because tables in Apache Cassandra are very similar to the tables of relational databases, this article describing them won't focus on basic points. Instead, we'll explore more Cassandra specific subjects, such as configuration or different types.

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Compaction in Apache Cassandra

Disk compaction helps to save space. Since Cassandra is supposed to store a lot of data, it can't miss this useful process.

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Partitioners in Apache Cassandra

Since Cassandra is distributed storage system, it holds data in different nodes. But how it determines data should be stored by each node ? It's the role of partitioners.

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Deletes in Apache Cassandra

Keeping old data eternally takes place and makes reads longer. Apache Cassandra is not an exception and has a mechanism to remove data.

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Example of data consistency in Apache Cassandra

Previously we've presented theory of data consistency in Cassandra. Now it's a good moment to show some examples of consistency levels.

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Data consistency in Cassandra

Distributed data brings a new problem to historical standalone relational databases - data consistency. Cassandra deals with this problem pretty nice with its different consistency levels.

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Data organization on disk in Apache Cassandra

Until now we're working with Cassandra without looking on what happens. It's a time to be a little bit more curious.

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Data part in Apache Cassandra

The previous article introduced us to Apache Cassandra by presenting vaguely its main concepts. This article focuses more in details on data topics.

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Introduction to Apache Cassandra

After some articles about data ingestion and serialization in Big Data applications, it's time to start to learn about storage. This part begins with Apache Cassandra.

This article presents basic concepts of Apache Cassandra. In the first part it tries to explain architecture and general concepts of this solution. The second part is focused more on developer topics and it describes some main points about data organization.

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Watches in Apache ZooKeeper

A lot of programming tools implement event-driven approach. Apache ZooKeeper isn't an exception for this rule with its system of watchers.

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ACL in Apache ZooKeeper

Apache ZooKeeper is very often compared to distributed file system. Because each file system has a feature to deal with file permissions, ZooKeeper, as a kind of file system, can't be different.

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