Re: Huge speed penalty using <>TRUE instead of =FALSE - Mailing list pgsql-bugs

On Friday 17 July 2009 12:45:47 Mikael Krantz wrote:
> It might be that your column may be NULL as well as TRUE or FALSE. I
> am no expert in this matter though.

Nulls also need to be considered when attempting to substitute purportedly
equivalent clauses.  But in this case it wouldn't actually matter, because

WHERE foo <> TRUE

and

WHERE foo = false

would both omit the row if foo is null.  Both expressions only return true if
foo has the value "false".  But again, this is data type specific knowledge.