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| -rw-r--r-- | lib/stdlib/doc/src/ets.xml | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml index ccccf7de88..622edc072e 100644 --- a/lib/stdlib/doc/src/ets.xml +++ b/lib/stdlib/doc/src/ets.xml @@ -188,6 +188,21 @@ is used to keep the table fixated during the entire traversal.</p> </item> </list> + <p>Traversals using <c>match</c> and <c>select</c> functions may not need to + scan the entire table depending on how the key is specified. A match + pattern with a <em>fully bound key</em> (without any match variables) will + optimize the operation to a single key lookup without any table traversal + at all. For <c>ordered_set</c> a <em>partially bound key</em> will limit the + traversal to only scan a subset of the table based on term order. A + partially bound key is either a list or a tuple with a prefix that is fully + bound. Example:</p> +<pre> +1> <input>T = ets:new(t,[ordered_set]), ets:insert(T, {"555-1234", "John Smith"}).</input> +true +2> <input>%% Efficient search of all with area code 555</input> +2> <input>ets:match(T,{[$5,$5,$5,$- |'$1'],'$2'}).</input> +[["1234","John Smith"]] +</pre> </section> <section> |