一、new(Name, Options) -> tid() | atom(),创建ets表.
Options = [Option],
目测常用的属性,
{keypos, Pos}：指定key的位置，每个元组的长度必须要大约Pos，也可以使用record的字段。
named_table:ets表注册.
Type:set | ordered_set | bag | duplicate_bag:表的类型，是否允许出现重复。
Access：public | protected | private
二、查询
1.lookup(Tab, Key) -> [Object]:根据key进行查询
Returns a list of all objects with the key Key in the table Tab.
In the case of set, bag and duplicate_bag, an object is returned only if the given key matches the key of the object in the table. If the table is an ordered_set however, an object is returned if the key given compares equal to the key of an object in the table. The difference being the same as between =:= and ==. As an example, one might insert an object with the integer() 1 as a key in an ordered_set and get the object returned as a result of doing a lookup/2 with the float() 1.0 as the key to search for.
2.fun2ms(LiteralFun) -> MatchSpec.
select(Tab, MatchSpec) -> [Match]
3.match(Tab, Pattern) -> [Match].
部分源码：
猜测：可以使用多个项元作为一个可以key，类似于复合索引
3> ets:new(my_ets,[named_table,{keypos,2},set]).
my_ets
4> ets:insert(my_ets,{1,aa,11}).
true
5> ets:insert(my_ets,{1,{aa,11},11}).
true
6> ets:lookup(my_ets,aa).
[{1,aa,11}]
7> ets:lookup(my_ets,{aa,11}).
[{1,{aa,11},11}]