Tag: row

Feed: SAS Blogs. Author: Rick Wicklin. I think every course in exploratory data analysis should begin by studying Anscombe's quartet. Anscombe's quartet is a set of four data sets (N=11) that have nearly identical descriptive statistics but different graphical properties. They are a great reminder of why you should graph your data. You can read about Anscombe's quartet on Wikipedia, or check out a quick visual summary by my colleague Robert Allison. Anscombe's first two examples are shown below: The Wikipedia article states, "It is not known how Anscombe created his data sets." Really? Creating different data sets that have ... Read More

Feed: Planet PostgreSQL. Have you ever heard about cursors in PostgreSQL or in SQL in general? If not you should definitely read this article in depth and learn how to reduce memory consumption in PostgreSQL easily. Cursors have been around for many years and are in my judgement one of the most underappreciated feature of all times. Therefore it makes sense to take a closer look at cursors and see what they can be used for.The purpose of a cursor in PostgreSQLConsider the following example: test=# CREATE TABLE t_large (id int); CREATE TABLE test=# INSERT INTO t_large SELECT * FROM ... Read More

Feed: R-bloggers. Author: Dror Berel's R Blog. Bioconductor S4 classes for high-throughput omics data Motivation Multi-omics data integration and analysis. What a beast! It is one of the major challenges in the era of personalized/precision medicine (or whatever you want to call it). Denfinetely mine, as someone who is expected to grab such messy data from multiple sources, allign and annotate it altogether, and then testing some interesting hypothesis with it. If you thought analysis of a single omic (microarray, RNAseq etc) is overwhelming, what about integration of multiple single-omic data? Multi-omics data adds another layer of priceless high-throughput biologic ... Read More

Feed: Planet MySQL; Author: Airbnb Engineering; Avoiding Double Payments in a Distributed Payments SystemHow we built a generic idempotency framework to achieve eventual consistency and correctness across our payments micro-service architecture.Jon ChewBlockedUnblockFollowFollowingApr 16Authors: Jon Chew and Ninad KhistiOne of the conference rooms in our San Francisco officeBackgroundAirbnb has been migrating its infrastructure to a Service Oriented Architecture (“SOA”). SOA offers many upsides, such as enabling developer specialization and the ability to iterate faster. However, it also poses challenges for billing and payments applications because it makes it more difficult to maintain data integrity. An API call to a service that makes ... Read More

Feed: Striving for Optimal Performance. The contents of the V$SQL_CS_HISTOGRAM view is used by the SQL engine to decide when a cursor is made bind aware, and therefore, when it should use adaptive cursor sharing. For each child cursor, the view shows three buckets. It is of general knowledge that the first one (BUCKET_ID equal 0) is associated with the executions that process up to and including 1,000 rows, the second one (BUCKET_ID equal 1) with the executions that processes between 1,001 and 1,000,000 rows, and the third one (BUCKET_ID equal 2) with the executions that processes more than 1,000,000 ... Read More

Feed: R-bloggers. Author: R on msperlin. The Central Bank of Brazil (BCB) offers access to its SGS system (sistema gerenciador de series temporais) with a official API available here. With time, I find myself using more and more of the available datasets in my regular research and studies. Over last weekend I decided to write my own API package that would make my life a lot easier. Package GetBCBData can fetch data efficiently and rapidly: Use of a caching system with package memoise to speed up repeated requests of data; Users can utilize all cores of the machine (parallel computing) ... Read More

Feed: R-bloggers. Author: Arvid Kingl. Categories Data Management Tags Case Study Data Manipulation Data Visualisation R Programming tidyverse This article was jointly written by Arvid J. Kingl & Viktor Konakovsky The Battle for Wesnoth is an open-source, turn-based strategy game. The game world is rich, with several factions, maps and literally hundreds of available units. In this tutorial, you will learn how to transform a medium-sized data sets, such as game metadata, into a useful format for further analysis using R. You will learn what key principles a tidy data set adheres to, why it is useful to follow them ... Read More

Feed: Planet MySQL; Author: Vlad Mihalcea; (Last Updated On: April 17, 2019) Introduction In this article, we are going to see how we can implement a database job queue using SKIP LOCKED. I decided to write this article while answering this Stack Overflow question asked by Rafael Winterhalter. Since SKIP LOCKED is a lesser-known SQL feature, it’s a good opportunity to show you how to use it and why you should employ it, especially when implementing a job queue task. How to implement a database job queue using SKIP LOCKED.@vlad_mihalcea https://t.co/sX2bkCXeHk pic.twitter.com/mg5WzOax0w— Java (@java) April 17, 2019 Domain Model Let’s ... Read More

Feed: R-bloggers. Author: Keith Goldfeld. Randomization is super useful because it usually eliminates the risk that confounding will lead to a biased estimate of a treatment effect. However, this only goes so far. If you are conducting a meditation analysis in the hopes of understanding the underlying causal mechanism of a treatment, it is important to remember that the mediator has not been randomized, only the treatment. This means that the estimated mediation effect is still at risk of being confounded. I never fail to mention this when a researcher tells me they are interested in doing a mediation analysis ... Read More

Feed: Planet MySQL; Author: FromDual; Last week at the MariaDB/MySQL Developer Training we had one participant asking some tricky questions I did not know the answer by heart.Also MariaDB documentation was not too verbose (here and here). So time to do some experiments: Prepared Statements and Multi-Row Inserts SQL> PREPARE stmt1 FROM 'INSERT INTO `test`.`test` (`data`) VALUES (?), (?), (?)'; Statement prepared SQL> SET @d1 = 'Bli'; SQL> SET @d2 = 'Bla'; SQL> SET @d3 = 'Blub'; SQL> EXECUTE stmt1 USING @d1, @d2, @d3; Query OK, 3 rows affected (0.010 sec) Records: 3 Duplicates: 0 Warnings: 0 SQL> DEALLOCATE PREPARE ... Read More