- 2.3.6 The Event Class
- 2.3.6.1 Event Types
- 2.3.6.2 Event Methods
- 2.3.6.2.1.
EventConstructor - 2.3.6.2.2.
Event::addEventColumn() - 2.3.6.2.3.
Event::addEventColumns() - 2.3.6.2.4.
Event::addTableEvent() - 2.3.6.2.5.
Event::getDurability() - 2.3.6.2.6.
Event::getEventColumn() - 2.3.6.2.7.
Event::getName() - 2.3.6.2.8.
Event::getNoOfEventColumns() - 2.3.6.2.9.
Event::getObjectStatus() - 2.3.6.2.10.
Event::getObjectVersion() - 2.3.6.2.11.
Event::getObjectId() - 2.3.6.2.12.
Event::getReport() - 2.3.6.2.13.
Event::getTable() - 2.3.6.2.14.
Event::getTableEvent() - 2.3.6.2.15.
Event::getTableName() - 2.3.6.2.16.
Event::mergeEvents() - 2.3.6.2.17.
Event::setDurability() - 2.3.6.2.18.
Event::setReport() - 2.3.6.2.19.
Event::setName() - 2.3.6.2.20.
Event::setTable()
This section contains descriptions of the public methods defined
by the Event class.
Description.
The Event constructor creates
a new instance with a given name, and optionally associated
with a table.
Signatures. It is possible to invoke this method in either of two ways, the first of these being by name only, as shown here:
Event
(
const char* name
)
Alternatively, you can use the event name and an associated table, like this:
Event
(
const char* name,
const NdbDictionary::Table& table
)
Parameters.
At a minimum, a name (as a constant
character pointer) for the event is required. Optionally, an
event may also be associated with a table; this argument, when
present, is a reference to a
Table object (see
Section 2.3.35, “The Table Class”).
Return value.
A new instance of Event.
Destructor.
A destructor for this class is supplied as a virtual method
which takes no arguments and whose return type is
void.
Description. This method is used to add a column on which events should be detected. The column may be indicated either by its ID or its name.
You must invoke
Dictionary::createEvent()
before any errors will be detected. See
Section 2.3.4.1.4, “Dictionary::createEvent()”.
If you know several columns by name, you can enable event
detection on all of them at one time by using
addEventColumns(). See
Section 2.3.6.2.3, “Event::addEventColumns()”.
Signature. Identifying the event using its column ID:
void addEventColumn
(
unsigned attrId
)
Parameters. This method takes a single argument, which may be either one of the following:
The column ID (
attrId), which should be an integer greater than or equal to0, and less than the value returned bygetNoOfEventColumns().The column's
name(as a constant character pointer).
Return value. None.
Description. This method is used to enable event detection on several columns at the same time. You must use the names of the columns.
As with addEventColumn(), you must invoke
Dictionary::createEvent()
before any errors will be detected. See
Section 2.3.4.1.4, “Dictionary::createEvent()”.
Signature.
void addEventColumns
(
int n,
const char** columnNames
)
Parameters. This method requires two arguments, listed here:
The number of columns
n(an integer).The names of the columns
columnNames—this must be passed as a pointer to a character pointer.
Return value. None.
Description. This method is used to add types of events that should be detected.
Signature.
void addTableEvent
(
const TableEvent te
)
Parameters.
This method requires a
TableEvent value.
Return value. None.
Description.
This method gets the event's lifetime and scope (that is, its
EventDurability).
Signature.
EventDurability getDurability
(
void
) const
Parameters. None.
Return value.
An EventDurability
value.
Description. This method is used to obtain a specific column from among those on which an event is defined.
Signature.
const Column* getEventColumn
(
unsigned no
) const
Parameters.
The number (no) of the column, as
obtained using getNoOfColumns() (see
Section 2.3.6.2.8, “Event::getNoOfEventColumns()”).
Return value.
A pointer to the Column
corresponding to no.
Description. This method obtains the name of the event.
Signature.
const char* getName
(
void
) const
Parameters. None.
Return value. The name of the event, as a character pointer.
Description. This method obtains the number of columns on which an event is defined.
Signature.
int getNoOfEventColumns
(
void
) const
Parameters. None.
Return value.
The number of columns (as an integer), or
-1 in the case of an error.
Description. This method gets the object status of the event.
Signature.
virtual Object::Status getObjectStatus
(
void
) const
Parameters. None.
Return value.
The object status of the event. For possible values, see
Section 2.3.29.1.3, “The Object::Status Type”.
Description. This method gets the event's object version (see Section 8.6, “NDB Schema Object Versions”).
Signature.
virtual int getObjectVersion
(
void
) const
Parameters. None.
Return value. The object version of the event, as an integer.
Description. This method retrieves an event's object ID.
Signature.
virtual int getObjectId
(
void
) const
Parameters. None.
Return value. The object ID of the event, as an integer.
Description. This method is used to obtain the reporting option in force for this event.
Signature.
EventReport getReport
(
void
) const
Parameters. None.
Return value.
One of the reporting options specified in
Section 2.3.6.1.3, “The Event::EventReport Type”.
Description.
This method is used to find the table with which an event is
associated. It returns a reference to the corresponding
Table object. You may also
obtain the name of the table directly using
getTableName().
Signature.
const NdbDictionary::Table* getTable
(
void
) const
Parameters. None.
Return value.
The table with which the event is associated—if there is
one—as a pointer to a
Table object; otherwise, this
method returns NULL. (See
Section 2.3.35, “The Table Class”.)
Description. This method is used to check whether a given table event will be detected.
Signature.
bool getTableEvent
(
const TableEvent te
) const
Parameters.
This method takes a single parameter, the table event's
type—that is, a
TableEvent value.
Return value.
This method returns true if events of
TableEvent type
te will be detected. Otherwise, the
return value is false.
Description.
This method obtains the name of the table with which an event
is associated, and can serve as a convenient alternative to
getTable(). (See
Section 2.3.6.2.13, “Event::getTable()”.)
Signature.
const char* getTableName
(
void
) const
Parameters. None.
Return value. The name of the table associated with this event, as a character pointer.
Description.
This method is used to set the merge events
flag, which is false by
default. Setting it to true implies that
events are merged as follows:
For a given
NdbEventOperationassociated with this event, events on the same primary key within the same global checkpoint index (GCI) are merged into a single event.A blob table event is created for each blob attribute, and blob events are handled as part of main table events.
Blob post/pre data from blob part events can be read via
NdbBlobmethods as a single value.
Currently this flag is not inherited by
NdbEventOperation, and must
be set on NdbEventOperation
explicitly. See Section 2.3.19, “The NdbEventOperation Class”.
Signature.
void mergeEvents
(
bool flag
)
Parameters.
A Boolean flag value.
Return value. None.
Description. This method sets an event's durability—that is, its lifetime and scope.
Signature.
void setDurability(EventDurability ed)
Parameters.
This method requires a single
EventDurability value
as a parameter.
Return value. None.
Description.
This method is used to set a reporting option for an event.
Possible option values may be found in
Section 2.3.6.1.3, “The Event::EventReport Type”.
Reporting of DDL events.
Prior to MySQL Cluster NDB 6.3.34, 7.0.15, and 7.1.4, it was
not necessary to set a specific reporting option in order to
receive DDL events from alter table and drop table events.
Beginning with MySQL Cluster NDB 6.3.34, 7.0.15, and 7.1.4,
this is no longer the case; in these and later versions, you
must call setReport() using the new
EventReport value
ER_DDL (added in the same MySQL Cluster
versions).
For example, to enable DDL event reporting in MySQL Cluster NDB
6.3.34, 7.0.15, and 7.1.4, and later on an
Event object named
myEvent, you must invoke this method as shown
here:
myEvent.setReport(NdbDictionary::Event::ER_DDL);
When upgrading to MySQL CLuster NDB 6.3.34, 7.0.15, or 7.1.4
from a version that supports automatic reporting of DDL events
where you wish to retain this behavior, you must add the
indicated setReport() call or calls, then
recompile, following the upgrade. If you merely replace the
old version of the libndbclient library
with the library included with the new MySQL Cluster version,
DDL events are no longer reported by default.
Signature.
void setReport
(
EventReport er
)
Parameters.
An EventReport option
value.
Return value. None.
Description.
This method is used to set the name of an event. The name must
be unique among all events visible from the current
application (see Section 2.3.6.2.5, “Event::getDurability()”).
You can also set the event's name when first creating it. See
Section 2.3.6.2.1, “Event Constructor”.
Signature.
void setName
(
const char* name
)
Parameters.
The name to be given to the event
(as a constant character pointer).
Return value. None.
Description. This method defines a table on which events are to be detected.
By default, event detection takes place on all columns in the
table. Use addEventColumn() to override
this behavior. For details, see
Section 2.3.6.2.2, “Event::addEventColumn()”.
Signature.
void setTable
(
const NdbDictionary::Table& table
)
Parameters.
This method requires a single parameter, a reference to the
table (see Section 2.3.35, “The Table Class”) on which events are to
be detected.
Return value. None.
