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| author | Sverker Eriksson <[email protected]> | 2010-11-02 18:08:04 +0100 |
|---|---|---|
| committer | Sverker Eriksson <[email protected]> | 2010-11-22 15:54:48 +0100 |
| commit | 454335cd043561cc9fe874bc325c152a0727328b (patch) | |
| tree | c12359d358fd8664bb5eb3b22cac80c5a8880e77 /lib/stdlib/doc/src | |
| parent | 7ceec2cef3643f2c2f63ae169f74da660803435b (diff) | |
| download | otp-454335cd043561cc9fe874bc325c152a0727328b.tar.gz otp-454335cd043561cc9fe874bc325c152a0727328b.tar.bz2 otp-454335cd043561cc9fe874bc325c152a0727328b.zip | |
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").
Diffstat (limited to 'lib/stdlib/doc/src')
| -rw-r--r-- | lib/stdlib/doc/src/ets.xml | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml index 702e1b928e..746f94d3f4 100644 --- a/lib/stdlib/doc/src/ets.xml +++ b/lib/stdlib/doc/src/ets.xml @@ -485,6 +485,9 @@ Error: fun containing local Erlang function calls <item><c>Item=protection, Value=public|protected|private</c> <br></br> The table access rights.</item> + <item><c>Item=compressed, Value=true|false</c> <br></br> + + Indicates if the table is compressed or not.</item> </list> </desc> </func> @@ -951,9 +954,10 @@ ets:select(Table,MatchSpec),</code> <type> <v>Name = atom()</v> <v>Options = [Option]</v> - <v> Option = Type | Access | named_table | {keypos,Pos} | {heir,pid(),HeirData} | {heir,none} | {write_concurrency,bool()} | {read_concurrency,bool()}</v> + <v> Option = Type | Access | named_table | {keypos,Pos} | {heir,pid(),HeirData} | {heir,none} | Tweaks</v> <v> Type = set | ordered_set | bag | duplicate_bag</v> <v> Access = public | protected | private</v> + <v> Tweaks = {write_concurrency,bool()} | {read_concurrency,bool()} | compressed</v> <v> Pos = int()</v> <v> HeirData = term()</v> </type> @@ -1047,13 +1051,13 @@ ets:select(Table,MatchSpec),</code> <item> <marker id="new_2_write_concurrency"></marker> <p><c>{write_concurrency,bool()}</c> - Performance tuning. Default is <c>false</c>. An operation that + Performance tuning. Default is <c>false</c>, in which case an operation that mutates (writes to) the table will obtain exclusive access, blocking any concurrent access of the same table until finished. If set to <c>true</c>, the table is optimized towards concurrent write access. Different objects of the same table can be mutated (and read) by concurrent processes. This is achieved to some degree - at the expense of single access and concurrent reader performance. + at the expense of sequential access and concurrent reader performance. The <c>write_concurrency</c> option can be combined with the <seealso marker="#new_2_read_concurrency">read_concurrency</seealso> option. You typically want to combine these when large concurrent @@ -1091,6 +1095,15 @@ ets:select(Table,MatchSpec),</code> option. You typically want to combine these when large concurrent read bursts and large concurrent write bursts are common.</p> </item> + <item> + <marker id="new_2_compressed"></marker> + <p><c>compressed</c> + If this option is present, the table data will be stored in a more compact format to + consume less memory. The downside is that it will make table operations slower. + Especially operations that need to inspect entire objects, + such as <c>match</c> and <c>select</c>, will get much slower. The key element + is not compressed in current implementation.</p> + </item> </list> </desc> </func> |