在 MySQL 的面试中有一类经典的面试题。比如：如何给正在线上运行的表执行 DDL 语句？ 回答这个问题，首先我们需要明确，执行 DDL 语句的时候，MySQL 会干什么？ 在 MySQL 5.6 之前，执行 DDL 语句的时候，会给表添加写锁，会阻塞该表其他所有的读写操作。这对 ...

其中数据类型必须显式声明，即使不修改数据类型也需重复原类型。例如将students表的name字段改为full_name： 修改字段名会影响依赖该字段的视图、存储过程和应用程序代码，需同步更新 建议在操作前备份数据，避免意外数据丢失 若需同时修改字段属性（如默认 ...

After copying a Parquet file into a MySQL table, the Parquet file seems to be locked and therefore cannot be deleted until the process is killed. We use tmp Parquet files to bridge data from 1 system ...

Perplexity AI is a great tool to have. It has a great set of features and works almost perfectly. Using it is also fairly easy and does not need any expertise, however, a lot of users seem to be ...

This tutorial shows you how to copy all text as a table from a screenshot in Snipping Tool on a Windows 11 PC. For this, we will use the Copy as table feature. It’s a new feature that generates ...

Snipping Tool has had the Text Actions feature for a year. It’s an OCR feature that identifies and extracts text from the screenshots. In a new experimental build, Microsoft has added an option to ...

Perplexity AI brings the power of generative AI to the search. This allows you to get more precise and compiled answers to your queries. You can even ask Perplexity to structure your data in many ...

This article was contributed by Edwin Sanchez who is a brand ambassador of Devart, software developer and project manager. There is this one problem that’s killing your MySQL database performance.