Archives mensuelles : mars 2014

Big data startup Databricks is now certifying applications for Spark

Spark was created as a processing framework for Hadoop that’s both faster and easier to use than the traditional MapReduce framework, and it’s catching on fast among folks writing big data applications.

Gigaom

Databricks , a new startup dedicated to commercializing the Apache Spark data-processing framework , has launched a « Certified on Spark » program for software vendors that want to tout their abilities to run on the increasingly popular technology. Spark was created as a processing framework for Hadoop that’s both faster and easier to use than the traditional MapReduce framework, and it’s catching on fast among folks writing big data applications.

Spark’s popularity is based on a few factors, including that it supports numerous programming languages (all of which are easier to write in than MapReduce) and supports faster data analysis both in-memory and on disk. It also allows for iterative queries on existing datasets, which — along with its speed — makes it more ideal for machine learning workloads. There are a number of workload-specific implementations on top of Spark, too, including Shark for interactive SQL queries, SparkR for statistical…

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Classé dans DATA, HADOOP

Read Only Users Can Lock Tables

NZ DBA

Can a user with only select privileges block transactions?  Yes!

Although this topic has been covered on the interweb already, I thought it was worth a mention because this fact had evaded me (and a team of experienced DBAs) until recently.

A session using an application support account, with resource limits and a « READ_ONLY » role, was found to be blocking another session’s transaction.  The user had selected a row with a popular GUI tool then accidentally clicked on a field in that row, which resulted in a select for update.

I was shocked, so I tried a simple experiment with the lock table command:

17:09:17 SYS@MYDB SQL> create user RO_USER identified by RO_USER; User created. 17:09:56 SYS@MYDB SQL> grant create session to RO_USER; Grant succeeded. 17:10:03 SYS@MYDB SQL> grant select on APP.key_table to RO_USER; Grant succeeded. 17:10:12 SYS@MYDB SQL> conn RO_USER/RO_USER Connected. 17:10:24 RO_USER@MYDB SQL> lock table APP.key_table in…

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Classé dans DATA

Petit astuce SQL : génération de requêtes SQL avec Excel

Transformer un tableau XLS en objets base de données, c’est
la base du cas de tests rapidement implémenté; CEWL….

La BI ça vous gagne!

Si c’est une évidence pour les vieux de la vieille, je me rends compte que tous ne sont pas forcément au courant de cette technique assez simple qui permet de générer des requêtes SQL avec Excel. Ça a surement déjà dû être bloggé 10 fois, mais ça va plus vite d’écrire l’article que de le chercher 😉

Vous partez depuis Excel, avec le tableau qu’on souhaiterait importer côté SQL:

Un tableau dans Excel

Vous y ajoutez la formule Excel suivante :

Tableau plus la formule qui suit

="SELECT '"&Tableau1[@[Colonne 1]]&"' AS Colonne1, "&Tableau1[@[Colonne 2]]&" AS Colonne2, '"&Tableau1[@[Colonne 3]]&"' AS Colonne3 UNION ALL"

Le principe vous l’avez compris : on compose une chaîne de caractère (= »SELECT… ») qui va correspondre à un SELECT simple (qui n’a pas besoin de FROM sur SQL Server, on rajoute FROM DUAL sur du Oracle) qui seront enchainés les uns aux autres par le UNION ALL (= »SELECT … UNION ALL »). Dans cette chaîne, on n’oublie pas de mettre les champs texte…

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Classé dans Uncategorized