Tag: collation

Feed: Featured Blog Posts - Data Science Central. Author: Jerry Cruise. Data wrangling is the most important step for business personnel to further analyze data or enter BI system. With the advent of the data age, data sources are becoming more and more diverse (files, big data platforms, databases, etc.). It brings a lot of challenges to data wrangling. In an enterprise, data is usually managed by IT personnel, who unifies the process of data extraction, data transformation and load warehouse, namely ETL, and then provides it to business personnel or visual system. Data can only be used after three stages: Raw ... Read More

Feed: Planet MySQL; Author: Severalnines; Migrating from Oracle database to open source can bring a number of benefits. The lower cost of ownership is tempting, and pushes a lot of companies to migrate. At the same time DevOps, SysOps or DBA’s need to keep tight SLA’s to address business needs. One of the key concerns when you plan data migration to another database, especially open source is to how to avoid data loss. It’s not too far fetched that someone accidentally deleted part of the database, someone forgot to include a WHERE clause in a DELETE query or run DROP ... Read More

Feed: Planet MySQL; Author: Federico Razzoli; According to Steve McQueen, it’s better to avoid BLOBTEXT and BLOB are MySQL variable-length types for long texts and long binary data. They are often misused. Sometimes they are used because they are an ORM’s default type for strings. Sometimes because the user thinks that VARCHAR has a 255 length limit (which was true in very old MySQL versions, but not today). In this article, I argue that sometimes these types should be avoided, and I talk a bit about good practices. Choosing between TEXT and BLOB TEXT and BLOB are similar datatypes. The ... Read More

Feed: Planet MySQL; Author: InsideMySQL.com; Dear MySQL users, MySQL Connector/J Version 8.0.16 is the GA release of the 8.0branch of MySQL Connector/J. It is suitable for use with MySQL Serverversions 8.0, 5.7 and 5.6. It supports the Java DatabaseConnectivity (JDBC) 4.2 API, and implements the X DevAPI. This release includes the following new features and changes, alsodescribed in more detail on https://dev.mysql.com/doc/relnotes/connector-j/8.0/en/news-8-0-16.html As always, we recommend that you check the “CHANGES” file in thedownload archive to be aware of changes in behavior that might affectyour application. To download MySQL Connector/J 8.0.16 GA, see the “Generally Available(GA) Releases” tab at http://dev.mysql.com/downloads/connector/j/ ... Read More

Feed: Planet MySQL; Author: Geir Hoydalsvik; The MySQL Development team is very happy to announce that MySQL 8.0.16 is now available for download at dev.mysql.com. In addition to bug fixes there are a few new features added in this release.  Please download 8.0.16 from dev.mysql.com or from the MySQL  Yum,  APT, or SUSE repositories. The source code is available at GitHub. You can find the full list of changes and bug fixes in the 8.0.16 Release Notes. Here are the highlights. Enjoy! SQL CHECK constraints (WL#929) This work by Praveenkumar Hulakund implements the CHECK constraint, i.e. the clause [CONSTRAINT [constraint_name]] ... Read More

Feed: Planet PostgreSQL. You liked this post or you have a comment? You can contact and help me here.22 Apr 2019 Tags: postgres, postgresql, , reindex A lot of work has been put into making Postgres 12 an excellent release to come, and in some of the features introduced, there is one which found its way into the tree and has been first proposed to community at the end of 2012. Here is the commit which has introduced it: commit: 5dc92b844e680c54a7ecd68de0ba53c949c3d605 author: Peter Eisentraut date: Fri, 29 Mar 2019 08:25:20 +0100 REINDEX CONCURRENTLY This adds the CONCURRENTLY option to the ... Read More

Feed: Planet PostgreSQL. Data checksums Added in PostgreSQL 9.3, data checksums can help to detect data corruption happening on the storage side. Checksums are only enabled if the instance was setup using initdb --data-checksums (which isn’t the default behavior), or if activated afterwards with the new pg_checksums tool also added in PostgreSQL 12. When enabled, checksums are written each time a block is written to disk, and verified each time a block is read from disk (or from the operating system cache). If the checksum verification fails, an error is reported in the logs. If the block was read by ... Read More

Feed: Planet PostgreSQL. tl;dr; SELECT COUNT(*) FROM (SELECT DISTINCT my_not_unique_indexed_column FROM my_table) t;I have a table that looks like this: songsearch=# d main_songtexthash Table "public.main_songtexthash" Column | Type | Collation | Nullable | -----------+--------------------------+-----------+----------+ id | integer | | not null | text_hash | character varying(32) | | not null | created | timestamp with time zone | | not null | modified | timestamp with time zone | | not null | song_id | integer | | not null | Indexes: "main_songtexthash_pkey" PRIMARY KEY, btree (id) "main_songtexthash_song_id_key" UNIQUE CONSTRAINT, btree (song_id) "main_songtexthash_text_hash_c2771f1f" btree (text_hash) "main_songtexthash_text_hash_c2771f1f_like" btree (text_hash varchar_pattern_ops) Foreign-key ... Read More

Feed: R-bloggers. Author: free range statistics - R. Swings are far from uniformLast week I introduced a Bayesian state space model of two-party-preferred voting intention for Australian federal elections. It treats the surveys from various polling firms as imperfect (potentially systematically imperfect) measurements of an unobserved latent variable of “true” voting intention, which manifests itself only every few years in the form of election results. The model estimates that latent value for every day that measurements exist, and going forward with increasing uncertainty past when there are measurements. The most likely day for the next federal election seems to be ... Read More

Feed: Planet MySQL; Author: MySQL Performance Blog; PREVIOUS POST Following my post MySQL 8 is not always faster than MySQL 5.7, this time I decided to test very simple read-only CPU intensive workloads, when all data fits memory. In this workload there is NO IO operations, only memory and CPU operations. My Testing Setup Environment specification Release | Ubuntu 18.04 LTS (bionic) Kernel | 4.15.0-20-generic Processors | physical = 2, cores = 28, virtual = 56, hyperthreading = yes Models | 56xIntel(R) Xeon(R) Gold 5120 CPU @ 2.20GHz ... Read More