The survey results from StackOverflow's developers survey are already here, and we can now declare the most popular databases for 2018. Without further ado, let's look into the results: So what can we learn from these results? The most popular database is MySQL, and not by far comes SQL Server. This wasn't very surprising, as… Continue reading Most popular databases in 2018 according to StackOverflow survey

This post's contentExporting MySQL database to a dump fileSecure the backup fileTransfer the backup fileImport MySQL dump to new serverValidate imported data in new serverAnother export & import optionImportant Notes Migrating a MySQL database usually requires only few simple steps, but can take quite some time, depending on the amount of data you would like… Continue reading How to Transfer a MySQL Database Between Two Servers?

What is a median value? The median of an array of numbers is the value of the middle item in the array, assuming the array is sorted. If the array has an even number of items, the median represents the average of the two middle values in the array. This value is very popular one… Continue reading How to calculate median value in MySQL using a simple SQL query

This post's contentThe ProblemPossible WorkaroundsSolving the problem using bad practice #1 (Run a query in a loop)Solving the problem using bad practice #2 (Cartesian product)Conclusion This post is based on a true story from one of our team members. Here at EverSQL, we have high appreciation for the MySQL database. Said that, every product has… Continue reading MySQL is not using my index – Join with a range condition

This post's contentWhy OFFSET is so slow?How to optimize slow OFFSET queries?Possible pitfalls / challengesConclusion Queries with LIMITs and OFFSETs are common in application that require pagination and in some cases might work well for a while. In many cases though, they become slow and painful once the OFFSET has a high value. Why OFFSET… Continue reading Faster Pagination in Mysql – Why Order By With Limit and Offset is Slow?

This post's contentThe Story of UTF8 VS UTF8MB4RecommendationHow to convert utf8 to utf8mb4 in MySQL? The Story of UTF8 VS UTF8MB4 I once got a call from the support team, saying that one of our customers reported that the application fails to save data in one of our business-critical features. The customer is seeing a… Continue reading MySQL utf8 vs utf8mb4 – What’s the difference between utf8 and utf8mb4?

This post's contentDoes it matter how many indexes I create?How to track redundant indexes in MySQL?How to drop a redundant index in MySQL?Summary Does it matter how many indexes I create? As a general rule of thumb, the more indexes you have on a table, the slower INSERT, UPDATE, and DELETE operations will be. Indexes… Continue reading How to find unused indexes in a MySQL database?

UPDATE: The top databases for 2018 were declared by StackOverflow's 2018 survey. The survey results from StackOverflow's developers survey are already here, and we can now declare the most popular databases for 2017. Without further ado, let's look into the results: So what can we learn from these results? The most popular database is MySQL,… Continue reading Most popular databases in 2017 according to StackOverflow survey

In several RDBMS databases, including MySQL, subqueries are often one of the causes for performance issues. Therefore, we have an incentive to avoid them whenever we can and to find alternative ways to implement our requirements. One of the most popular uses for subselects in SQL is when one needs to fetch the first, last,… Continue reading Select max, min, last row for each group in SQL without a subquery