Shulou(Shulou.com)05/31 Report--

This article mainly introduces "what are the new functions of MYSQL8". In daily operation, I believe many people have doubts about the new functions of MYSQL8. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "what are the new features of MYSQL8?" Next, please follow the editor to study!

One of the biggest changes between MYSQL 8 and MYSQL 5.7 is that the atomicity of the data dictionary is guaranteed. No longer FRM files and Idb files, there is always a bit of panic during the DDL part of the datasheet. And one of the big changes is called Serialized Dicitionary information.

Previously, MYSQL 5.X had a toolset that allows you to read FRM files while MYSQL is down and show the structure of the table through a toolset written by mysqlfrm (via PYTHON). MYSQL 8 will no longer have such a thing, and the toolset will actually be offline a long time ago, so MYSQL 8 has introduced a new way to read data format files.

This tool is ibd2sdi.

We can use ibd2sdi to read the table structure of the data when the system is started, and output

Output into json format.

The dictionary table will not be viewable in MYSQL 8, and if you need to view it, you will need to add the debug parameter when compiling MYSQL, and you will need to run special commands to view the data.

The main reason for doing this is that the original dictionary tables of MYSQL 5.x are difficult to expand and are not consistent, while MYSQL8 corrects this problem and stores data dictionaries as SDI and JSON.

Through the tool, we can initially see the information of SDI, but what exactly does SDI bring?

1 inconsistency caused by non-transactional storage when performing DDL operations

2 secure Crash when DDL operation fails

3 avoiding replication is a challenging problem because DDL is not atomic

4 the problem of difficulty in extending the table structure

5 added cache of SDI, accelerated query of data by adding cache of metadata metadata, and managed related CACHE by LRU.

At the same time, there is a drawback, that is, it may take more time for DDL because it has to rewrite to storage, undo log, redo log instead of writing directly to the frm file.

The above figure is also a new function added in 8.00.In the past, we read the status of the table directly, but in the version after mysql 8.014, add the above parameters, the status of the read table is to read the cache, and to refresh the cache, you can challenge the expiration time or analyze table on the.

At this point, the study of "what are the new features of MYSQL8" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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