diff options
Diffstat (limited to 'lib/stdlib/doc/src/ets.xml')
| -rw-r--r-- | lib/stdlib/doc/src/ets.xml | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/lib/stdlib/doc/src/ets.xml b/lib/stdlib/doc/src/ets.xml index ccccf7de88..b9ceaa1d69 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> @@ -1993,9 +2008,8 @@ true</pre> <p>This function provides an efficient way to update one or more counters, without the trouble of having to look up an object, update the object by incrementing an element, and insert the resulting - object into the table again. (The update is done atomically, - that is, no process - can access the ETS table in the middle of the operation.)</p> + object into the table again. The operation is guaranteed to be + <seealso marker="#concurrency">atomic and isolated</seealso>.</p> <p>This function destructively update the object with key <c><anno>Key</anno></c> in table <c><anno>Tab</anno></c> by adding <c><anno>Incr</anno></c> to the element at position |