即將釋出的R14B01要支援ets的壓縮，更大程度的提高記憶體的利用率。
在github上可以看到這個分支，有興趣的同學可以下載下來看看。

壓縮的時候只壓縮value, key是不壓縮的。 value特別簡單型別的eterm也是不壓縮的，因為zip壓縮需要一定長度的內容，而且壓縮本身也要加入一點的overload.

以下是sverker (author)的提交log.

ETS ‘compressed’ option.

The compressed format is using a slighty modified variant of the extern format
(term_to_binary). To not worsen key lookup’s too much, the top tuple itself
and the key element are not compressed. Table objects with only immediate
non-key elements will therefor not gain anything (but actually consume one
extra word for “alloc_size”).

我們來試驗下吧：

# erl +ec
Erlang R14B01 (erts-5.8.2) [/source] [64-bit] [smp:48:48] [rq:48] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.2  (abort with ^G)
1> ets:all().
[8207,4110,13,file_io_servers,inet_hosts_file_byaddr,
 inet_hosts_file_byname,inet_hosts_byaddr,inet_hosts_byname,
 inet_cache,inet_db,global_pid_ids,global_pid_names,
 global_names_ext,global_names,global_locks,ac_tab]
2> ets:info(8207).
[{compressed,true},
 {memory,92},
 {owner,<0.26.0>},
 {heir,none},
 {name,shell_records},
 {size,0},
 {node,
 
[email protected]},
 {named_table,false},
 {type,ordered_set},
 {keypos,1},
 {protection,public}]
3> ets:new(xx, [public, compressed]).
16400
4> ets:info(16400).                  
[{compressed,true},
 {memory,302},
 {owner,<0.32.0>},
 {heir,none},
 {name,xx},
 {size,0},
 {node,
 
[email protected]},
 {named_table,false},
 {type,set},
 {keypos,1},
 {protection,public}]

祝大家玩的開心。

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