ordered_set 上的 Erlang Mnesia select 是否以 Erlang 术语顺序给出列表？

Question

在文档中，我不清楚我是否需​​要按顺序遍历 next 或 foldl（有人提到 foldr 的顺序与 ordered_set 相反，所以可以推测 foldl 是以相同的顺序）或者如果我可以使用 select 并依赖它被订购（假设 ordered_set table）

Answer 1

can I use select and rely upon it being ordered (assuming ordered_set table)

ets:select/2:

For tables of type ordered_set, objects are visited in the same order as in a first/next traversal. This means that the match specification is executed against objects with keys in the first/next order and the corresponding result list is in the order of that execution.

ets:first/1:

Returns the first key Key in table Tab. For an ordered_set table, the first key in Erlang term order is returned.

Table Traversal:

Traversals using match and select functions may not need to scan the entire table depending on how the key is specified. A match pattern with a fully bound key (without any match variables) will optimize the operation to a single key lookup without any table traversal at all. For ordered_set a partially bound key will limit the traversal to only scan a subset of the table based on term order.

table 类型 ordered_set 到 return 的搜索结果随机排序对我来说毫无意义。