清单16给出了一个查询例子，在这个查询中，向优化器提示空间谓词只有很少的符合条件的行。
Listing 16 gives an example of a query where the optimizer is given the hint that the spatial predicate will only have very few qualifying rows.
GWT开发文档提示说必须慎重使用JSNI，因为不能保证浏览器的可移植性，而且编译代码的优化是有限制的。
The GWT development documentation warns that JSNI must be used with discretion because browser portability isn't guaranteed, and the compiled code optimization is restrictive.
C99引入了一个限定词restrict，它可以向编译器给出关于指针的优化提示。
C99 introduced a qualifier, restrict, which can give a compiler optimization hints about Pointers.
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