On 2/3/11 1:34 PM, Shaun Thomas wrote:
I must say that this purist attitude is extremely surprising to me.
All the major DB vendors support optimizer hints, yet in the
Postgres community, they are considered bad with almost religious
fervor. Postgres community is quite unique with the fatwa against
hints.
You missed the argument. The community, or at least the devs, see hints
as an ugly hack.
Let's kill the myth right now that Postgres doesn't have hints. It DOES have hints.
Just read this forum for a few days and see how many time there are suggestions like "disable nested loops" or "disable seqscan", or "change the random page cost", or "change the join collapse limit".
All of these options are nothing more than a way of altering the planner's choices so that it will pick the plan that the designer already suspects is more optimal.
If that's not a hint, I don't know what is.
Craig
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