What is difference between libmysqlclient.a and libmysqlclient_r.a?

Question

Which should I use to link for mysqlclient library? What is the difference between them? I can't seem to find the answer. Thanks.

Answer 1

libmysqlclient_r.a is thread-safe

Answer 2

Newer versions of the MySQL client distributions do not include the "_r" version. Some may have a symbolic link from libmyqslclient_r.a to libmyqslclient.a

Answer 3

libmysqlclient_r.a is "re-entrant". https://en.wikipedia.org/wiki/Reentrant_%28subroutine%29 But as Garret pointed out, there is no difference in newer versions (both are re-entrant).

Answer 4

libmysqlclient_r is guaranteed to be thread-safe per connection. However, MySQL documentations prior to MySQL 5.5 are vague on whether multi-threaded applications can link to libmysqlclient as long as there are no simultaneous access on a single MySQL connection handle.

Base on experience though, I used libmysqlclient for applications that processes 100-400 queries per second and have been running for 5 years. I've yet to encounter any issues.