Shulou(Shulou.com)06/02 Report--

This article introduces the relevant knowledge of "how to use C++ to delete large tables in the database". In the operation of actual cases, many people will encounter such a dilemma. Next, let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Background: the IO pressure of the database is very great. If the large table is deleted online, it will cause great jitter to IO and business. The common practice as a DBA is to establish a hard connection between .frm and .ibd, and then on drop table tablename;, but the table file still exists on this machine. If you delete the table file directly with rm, it will cause the until of IO to reach 100%.

Question: so how to avoid IO reaching 100% when deleting files?

Solution: gradually erase files through ftruncate. Below, I provide my own slowrm to delete files. Test the io usage between 10-20%, and delete at a speed of more than 100G per hour (here is only a rough version, you can modify it yourself)

# include

# include

# include

# include

# include

# include

/ / determine whether the input is legal

Int fileInputLegal (const char * pfile=nullptr)

Int main (int argc,char * argv []) {

/ / use stat to get the file size

/ / call open to open the file and get the file descriptor

/ / call ftrucate to reduce the size of the file until 0

Int fd =-1

/ / this parameter has been adjusted

Int deleteBytes = 1024700

/ / the purpose is to get the length of the file

Struct stat buf

Off_t fileSize = 0

If (argc! = 2) {

Std::cout

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