diff options
Diffstat (limited to 'lib/mnesia/doc/src/mnesia.xml')
| -rw-r--r-- | lib/mnesia/doc/src/mnesia.xml | 64 |
1 files changed, 47 insertions, 17 deletions
diff --git a/lib/mnesia/doc/src/mnesia.xml b/lib/mnesia/doc/src/mnesia.xml index d76471d922..7a8f796cee 100644 --- a/lib/mnesia/doc/src/mnesia.xml +++ b/lib/mnesia/doc/src/mnesia.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2010</year> + <year>1996</year><year>2011</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -161,6 +161,14 @@ If a new item is inserted with the same key as </p> </item> <item> + <p><c>majority</c> This attribute can be either <c>true</c> or + <c>false</c> (default is <c>false</c>). When <c>true</c>, a majority + of the table replicas must be available for an update to succeed. + Majority checking can be enabled on tables with mission-critical data, + where it is vital to avoid inconsistencies due to network splits. + </p> + </item> + <item> <p><c>snmp</c> Each (set based) Mnesia table can be automatically turned into an SNMP ordered table as well. This property specifies the types of the SNMP keys. @@ -650,6 +658,17 @@ mnesia:change_table_copy_type(person, node(), disc_copies) </desc> </func> <func> + <name>change_table_majority(Tab, Majority) -> {aborted, R} | {atomic, ok}</name> + <fsummary>Change the majority check setting for the table.</fsummary> + <desc> + <p><c>Majority</c> must be a boolean; the default is <c>false</c>. + When <c>true</c>, a majority of the table's replicas must be available + for an update to succeed. When used on fragmented tables, <c>Tab</c> + must be the name base table. Directly changing the majority setting on + individual fragments is not allowed.</p> + </desc> + </func> + <func> <name>clear_table(Tab) -> {aborted, R} | {atomic, ok}</name> <fsummary>Deletes all entries in a table.</fsummary> <desc> @@ -753,6 +772,14 @@ mnesia:change_table_copy_type(person, node(), disc_copies) priority will be loaded first at startup. </p> </item> + <item> + <p><c>{majority, Flag}</c>, where <c>Flag</c> must be a boolean. + If <c>true</c>, any (non-dirty) update to the table will abort unless + a majority of the table's replicas are available for the commit. + When used on a fragmented table, all fragments will be given + the same majority setting. + </p> + </item> <item> <p><c>{ram_copies, Nodelist}</c>, where <c>Nodelist</c> is a list of the nodes where this table @@ -799,7 +826,7 @@ mnesia:change_table_copy_type(person, node(), disc_copies) </item> <item> <p><c>{local_content, Bool}</c>, where <c>Bool</c> must be - either <c>true</c> or <c>false</c>. The default value is <c>false</c>.\011 </p> + either <c>true</c> or <c>false</c>. The default value is <c>false</c>.</p> </item> </list> <p>For example, the following call creates the <c>person</c> table @@ -1022,7 +1049,7 @@ mnesia:create_table(person, <name>dirty_last(Tab) -> Key | exit({aborted, Reason}) </name> <fsummary>Return the key for the last record in a table.</fsummary> <desc> - <p>This function works exactly + <p>This function works exactly like <c>mnesia:dirty_first/1</c> but returns the last object in Erlang term order for the <c>ordered_set</c> table type. For all other table types, <c>mnesia:dirty_first/1</c> and @@ -1063,11 +1090,11 @@ mnesia:create_table(person, <name>dirty_prev(Tab, Key) -> Key | exit({aborted, Reason}) </name> <fsummary>Return the previous key in a table. </fsummary> <desc> - <p>This function works exactly + <p>This function works exactly like <c>mnesia:dirty_next/2</c> but returns the previous object in Erlang term order for the ordered_set table type. For all other table types, <c>mnesia:dirty_next/2</c> and - <c>mnesia:dirty_prev/2</c> are synonyms.\011 </p> + <c>mnesia:dirty_prev/2</c> are synonyms.</p> </desc> </func> <func> @@ -1135,7 +1162,7 @@ mnesia:create_table(person, </list> <p>If two processes perform <c>mnesia:dirty_update_counter/3</c> simultaneously, both updates will take effect without the - risk of loosing one of the updates. The new value + risk of losing one of the updates. The new value <c>NewVal</c> of the counter is returned.</p> <p>If <c>Key</c> don't exits, a new record is created with the value <c>Incr</c> if it is larger than 0, otherwise it is set to 0.</p> @@ -1334,7 +1361,7 @@ mnesia:create_table(person, <name>foldr(Function, Acc, Table) -> NewAcc | transaction abort </name> <fsummary>Call Function for each record in Table </fsummary> <desc> - <p>This function works exactly as + <p>This function works exactly like <c>foldl/3</c> but iterates the table in the opposite order for the <c>ordered_set</c> table type. For all other table types, <c>foldr/3</c> and @@ -1512,14 +1539,14 @@ mnesia:create_table(person, <fsummary>Check if code is running in a transaction.</fsummary> <desc> <p>When this function is executed inside a transaction context - it returns <c>true</c>, otherwise <c>false</c>.</p> + it returns <c>true</c>, otherwise <c>false</c>.</p> </desc> </func> <func> <name>last(Tab) -> Key | transaction abort </name> <fsummary>Return the key for the last record in a table.</fsummary> <desc> - <p>This function works exactly + <p>This function works exactly like <c>mnesia:first/1</c> but returns the last object in Erlang term order for the <c>ordered_set</c> table type. For all other table types, <c>mnesia:first/1</c> and @@ -1698,11 +1725,11 @@ mnesia:create_table(person, <name>prev(Tab, Key) -> Key | transaction abort </name> <fsummary>Return the previous key in a table. </fsummary> <desc> - <p>This function works exactly + <p>This function works exactly like <c>mnesia:next/2</c> but returns the previous object in Erlang term order for the ordered_set table type. For all other table types, <c>mnesia:next/2</c> and - <c>mnesia:prev/2</c> are synonyms.\011 </p> + <c>mnesia:prev/2</c> are synonyms.</p> </desc> </func> <func> @@ -1737,7 +1764,10 @@ mnesia:create_table(person, <c>write</c> and <c>sticky_write</c> are supported. </p> <p>If the user wants to update the record it is more efficient to - use <c>write/sticky_write</c> as the LockKind. + use <c>write/sticky_write</c> as the LockKind. If majority checking + is active on the table, it will be checked as soon as a write lock is + attempted. This can be used to quickly abort if the majority condition + isn't met. </p> </desc> </func> @@ -1891,10 +1921,10 @@ mnesia:create_table(person, <p>For example to find the names of all male persons with an age over 30 in table Tab do:</p> <code type="none"> -\011 MatchHead = #person{name='$1', sex=male, age='$2', _='_'}, -\011 Guard = {'>', '$2', 30}, -\011 Result = '$1', -\011 mnesia:select(Tab,[{MatchHead, [Guard], [Result]}]), +MatchHead = #person{name='$1', sex=male, age='$2', _='_'}, +Guard = {'>', '$2', 30}, +Result = '$1', +mnesia:select(Tab,[{MatchHead, [Guard], [Result]}]), </code> </desc> </func> @@ -2835,7 +2865,7 @@ raise(Name, Amount) -> </func> <func> <name>write(Tab, Record, LockKind) -> transaction abort | ok </name> - <fsummary>Write an record into the database.</fsummary> + <fsummary>Write a record into the database.</fsummary> <desc> <p>Writes the record <c>Record</c> to the table <c>Tab</c>. </p> |