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Exploring Word2Vec
In my previous blog post, I explored some of the early ways of word embeddings and their shortcomings. The purpose of this post is to explo...
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The latest blog posts to take off on Hacker News. 1,888 posts.
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User-defined Order in SQL
Some applications, such as todo lists, need to maintain a user-defined order of items. The challenge is that the order is arbitrary and can change when the user rearranges items:
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The 600+ Companies PayPal Shares Your Data With
One of the effects of GDPR—the new EU General Data Protection Regulation—is that we’re all going to be learning a lot more about who collects our data and what they do with it. Consider PayPal, that just released a list of over 600 companies they share customer data with. Here’s a good visualization of that data. Is…
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Anna: A Fast, Scalable, Flexibly Consistent Key-Value Store
There’s fast and there’s fast. This post is about Anna*, a key/value database design from our team at Berkeley that’s got phenomenal speed and buttery smooth scaling, with an unpr…
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Notes on Analytics and Tracking in Onavo Protect for iOS
Recent media coverage of Onavo Protect encouraged me to investigate the code for the iOS version of their app. I wanted to determine what…
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A new storage engine for PostgreSQL to provide better control over bloat
In the past few years, PostgreSQL has advanced a lot in terms of features, performance, and scalability for many-core systems. However, o...
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NumPy Exercises for Data Analysis in Python
The goal of the numpy exercises is to serve as a reference as well as to get you to apply numpy beyond the basics. The questions are of 4 levels of difficulties with L1 being the easiest to L4 being the hardest.
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Pivot – Rows to Columns
Pivot SQL tables with CASE or FILTER. Turn rows into columns for the entity-attribute-value model (EAV).
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Do or undo – there is no VACUUM
What if PostgreSQL didn’t need VACUUM at all? This seems hard to imagine. After all, PostgreSQL uses multi-version concurrency control (MVC...
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Postgres indexes under the hood
Many software engineers use database indexes every day, but few of us really understand how they work. In this post I’ll explain: How indexing works in Postgres using B-Trees What B-Trees are Why they are a good fit for this problem Indexes in Postgres Postgres actually offers 4 different kinds of indexes for…
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PostgreSQL 10: Partitions of partitions
PostgreSQL version 10 brings a much anticipated feature: (Native) Table Partitioning .
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Full-Text Search in Django with PostgreSQL
Article based on my talk about Full-text search in Django with PostgreSQL.
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The State of Vacuum in Postgres
In a recent blog post , I talked about why every system that implements MVCC needs some scheme for removing old row versions, and how VACUUM...
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Docker for data scientists: Introduction and use cases
Data scientists looking to learn Docker can get a brief intro and a look at how to improve your workflow
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SQL Keys in Depth
The internet is full of dogmatic commandments for choosing and using keys in relational databases. At times it verges on a holy war: should you use natural or artificial keys? Auto-incrementing integers, UUIDs?
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PostgreSQL Benchmark on FreeBSD, CentOS, Ubuntu Debian and OpenSUSE
In this post, I’m going to show benchmark results of the recently released PostgreSQL 10.1. I’ve benchmarked the DB on these OSes (all are 64-bit):
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Jsonb: Stories about performance
As such, there’s really no “standard” benchmark that will inform you about the best technology to use for your application. Only your requirements, your data, and your infrastructure can tell you what you need to know.
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Four DB2 Code Bases?
Many years ago I worked on IBM DB2 and so I occasionally get the question, “how the heck could you folks possibly have four relational database management system code bases?” Some go on to argue that a single code base would have been much more efficient. That’s certainly true. And, had we moved to a single code base…
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Modes, Medians and Means: A Unifying Perspective
Introduction / Warning Link to heading Any traditional introductory statistics course will teach students the definitions of modes, medians and means. But, because introductory courses can’t assume that students have much mathematical maturity, the close relationship between these three summary statistics can’t be…
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The Ethereum-blockchain size will not exceed 1TB anytime soon
Once a month users post a chart on `r/ethereum` predicting the blockchain size of Ethereum will soon exceed 1 TB. I want to clean up with some stories around the Ethereum-blockchain size in this article and try to explain why this chart is technically correct, but not the full picture...
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Three-Valued Logic
Making decision despite missing SQL data (NULL): How to avoid OR…IS NULL in the WHERE clause.
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Introduction to R Programming
This is a detailed step-by-step introduction to R programming. Starting with the two major reasons to learn R for Data Science, it will guide you through the installation process, and prepare you for the basics of R: arithmetics, variables assignment, data types, functions, and documentations.
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Switching Jobs
When people move to different jobs, here’s where they go.
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Scaling Postgres with Read Replicas and Using WAL to Counter Stale Reads
Scaling out operation with read replicas and avoiding the downside of stale reads by observing replication progress.