Seeing things from the user's point of viewMon, Mar 4, 2013 in Commentary Databases
I was discussing how to avoid surprising users and someone pointed out that what seems intuitive and rational to one person is often complete insanity for others. The mental gap between a developer and a user can often be a chasm far too wide to cross. Of all the bug reports I’ve filed against MySQL, here is my all-time favorite:
select * from t where a >= 1.0order by a;
Does not cause an error. I believe it should, because there should be a whitespace before ORDER BY.
Similar syntax errors such as “
select 1e0from dual” were also accepted as valid SQL. Much soul-searching later, the official reply from MySQL’s development team:
The server behaves properly here:
- “1″ alone can not be an identifier, because it’s followed by a “.”
- therefore, the lexer parses “1″ as the beginning of a number, and ends up with “1.0″ as one token.
The next token will be “order”, a keyword.
There is nothing special to document here either. What was reported is not a bug in the server, and is not a documentation bug.
What just happened here? It’s fairly simple. Never attribute to malice that which can be adequately explained by tunnel vision. The developer decided that the SQL isn’t a syntax error because the lexer is designed to parse it. If the developer were able to stand in a user’s shoes for a moment, this answer would be obviously absurd. But when you live deep in the dungeons of a large codebase, you lose the ability (despite your best intentions) to see a normal user’s point of view.
For this reason I often doubt my own judgment. I’m ignorant of my ignorance. It’s a very “meta” problem. I have to rely on others to give me a sanity check.
I suggest, as a topic of discussion, that the willingness and ability to accept others’ judgment over one’s own is an essential characteristic of good leadership. I also suggest that knowing when this is appropriate is another attribute a good leader must have. Both of these are very difficult in my experience.
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.