Tis a gift to be simple

I was just reading up on the syntax for index hints in MySQL, and noticed this:

An index_name value need not be a full index name. It can be an unambiguous prefix of an index name. If a prefix is ambiguous, an error occurs. I actually prefer not to have extra “syntactic sugar” features such as this. It helps avoid bugs and unexpected behavior. Even if I don’t use it intentionally, I can get bitten by it, if someone adds another index whose name has the same prefix as one that I already use:

mysql> create table t(a int primary key);
mysql> select * from t force index(PRIMAR);
Empty set (0.00 sec)

mysql> alter table t add key PRIMARY_2(a);

mysql> select * from t force index(PRIMAR);
ERROR 1176 (HY000): Key 'PRIMAR' doesn't exist in table 't'

I actually considered adding support for prefixes of command-line options to Maatkit, once upon a time. This way you’d be able to say --rep instead of spelling out the full option name; some of the options are very long-winded. This is pretty standard behavior, and even the MySQL command-line tools let you do it. But I came to my senses quickly when I realized that this would never let us rest easy about backwards and forwards compatibility. Even if it weren’t a potential problem, I think there are more important things to work on in Maatkit.


About The Author

Baron is the founder and CEO of VividCortex. He is the author of High Performance MySQL and many open-source tools for performance analysis, monitoring, and system administration. Baron contributes to various database communities such as Oracle, PostgreSQL, Redis and MongoDB.


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