Data engineering articles

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Apache Airflow Big Data algorithms Big Data problems - solutions Data engineering patterns General Big Data General data engineering Graphs SQL

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Scalable Bloom filter

Bloom filter has a lot of versions addressing its main drawbacks - bounded source and add-only character. One of them is Scalable Bloom filter that fixes the first issue.

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Bloom filter

After HyperLogLog and Count-min sketch it's time to cover another popular probabilistic algorithm - Bloom filter.

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Cardinality estimation with linear probabilistic counting

This post follows the series about approximation algorithms. But unlike before, this time we'll focus on simpler solution, the linear probabilistic counting.

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Consensus problem and the Raft consensus algorithm

During long years the Paxos protocol was one of most serious solutions for consensus problems. However in 2013 Diego Ongaro and John Ousterhout from Stanford University proposed an alternative called Raft.

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Window functions in SQL

Window functions are one of another SQL features that we'll probably discover during the work with data-oriented application. They can be also used in more classical programs though.

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Immutability and key-value storage

The immutability is a precious property of systems dealing with a lot of data. It's especially true when something goes wrong and we must recover quickly. Since the data is immutable, the cleaning step is not executed and with some additional computation power, the data can be regenerated efficiently.

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ACID 2.0

ACID is a well-known acronym for almost all developers growing with the RDBMS as the main storage. However with the popularization of NoSQL and distributed computing, another ACID acronym appeared - ACID 2.0.

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Conflict-Free Replicated Data Types - flags, graphs and maps

Previous post about the Conflict-free Replicated Data Types presented some of basic structures of this type. This one will describe some of recently uncovered types such as: flags, graphs and arrays.

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Immutability in Big Data

The interest of immutability in Big Data is often difficult to understand at the first glance. After all it introduces some complexity - especially at the reading path. But when the first problems appear and some of data need to be recomputed in order, the immutability comes to the rescue.

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Conflict-Free Replicated Data Type

Pessimistic replication requires a synchronous communication between the main node writing the data and the replicas. However in some cases the optimistic replication can be more efficient and still guarantee the same final result. One of solutions from this category are conflict-free replicated data types.

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Hierarchical queries

SQL hides for the most of its daily users a lot of interesting and powerful functions that though are not used very frequently. One of them are hierarchical queries.

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Frequency estimation with Count-min sketch

HyperLogLog algorithm described some weeks ago is not the single one approximate solution in the world of Big Data applications. Another one is Count-min sketch.

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Correlated subqueries

Even though the RDBMS is more and more completed (replaced?) by NoSQL solutions, it still remains an important piece of the data processing. It's even more true with the distributed databases as BigQuery supporting SQL standards so the correlated subqueries. But they're also implemented in other Big Data engines as Spark SQL or more classical ones as PostgreSQL.

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Data processing frameworks concepts

Modern data processing frameworks offer a wide range of features. At first glance this number can scary. Fortunately they can be discovered sequentially and often are common for the most popular frameworks.

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Conflict resolution in distributed applications - vector clocks

Dynamo paper, already quoted here in other posts, was published in 2007. It's 10 years ago. Even though the time passed, it still proposes interesting concepts to know for data-driven applications. And one of them are vector clocks used to conflict resolution.

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Secondary index in NoSQL data stores

The data organization in key-value oriented NoSQL databases is very often based on a pair of keys: partition and sorting. However they also offer other feature called secondary index that can be a good alternative to previously described index table pattern.

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Index table pattern in NoSQL

Good write throughput and horizontal scalability are maybe the most visible advantages of NoSQL storage systems. However very often people with a solid RDBMS background fall in the trap of index that can't be so easily created. Fortunately, a lot of patterns helping to deal with this problem exist. One of them is the index table pattern.

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Introduction to data quality

Dealing with a lot of data is a time consuming activity but dealing with a lot of data and ensuring its high value is even more complicated. It's one of the reasons why the data quality should never be neglected. After all, it's one of components providing accurate business insights and facilitating strategic decisions.

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Polyglot persistence - definition and examples

The popularization of NoSQL data stores brought a new concept in data management called polyglot persistence. This term is very similar to polyglot programming and it'll be presented below.

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Log-structured file system

Sequential writes made their proofs in distributed data-driven systems. Usually they perform better than random writes, especially in systems with intensive writes. Beside the link to the Big Data, the sequential writes are also related to another type of systems called log-structured file systems that were defined late 1980's.

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