/*
** Create an sps that is used by the trigger.
*/
private SPSDescriptor createSPS(
LanguageConnectionContext lcc,
DataDescriptorGenerator ddg,
DataDictionary dd,
TransactionController tc,
UUID triggerId,
SchemaDescriptor sd,
UUID spsId,
UUID compSchemaId,
String text,
boolean isWhen,
TableDescriptor triggerTable)
throws StandardException {
if (text == null) {
return null;
}
/*
** Note: the format of this string is very important.
** Dont change it arbitrarily -- see sps code.
*/
String spsName =
"TRIGGER"
+ (isWhen ? "WHEN_" : "ACTN_")
+ triggerId
+ "_"
+ triggerTable.getUUID().toString();
SPSDescriptor spsd =
new SPSDescriptor(
dd,
spsName,
(spsId == null) ? dd.getUUIDFactory().createUUID() : spsId,
sd.getUUID(),
compSchemaId == null ? lcc.getDefaultSchema().getUUID() : compSchemaId,
SPSDescriptor.SPS_TYPE_TRIGGER,
true, // it is valid
text, // the text
true); // no defaults
/*
** Prepared the stored prepared statement
** and release the activation class -- we
** know we aren't going to execute statement
** after create it, so for now we are finished.
*/
spsd.prepareAndRelease(lcc, triggerTable);
dd.addSPSDescriptor(spsd, tc);
return spsd;
}
/**
* This is the guts of the Execution-time logic for CREATE TRIGGER.
*
* @see ConstantAction#executeConstantAction
* @exception StandardException Thrown on failure
*/
public void executeConstantAction(Activation activation) throws StandardException {
SPSDescriptor whenspsd = null;
SPSDescriptor actionspsd;
LanguageConnectionContext lcc = activation.getLanguageConnectionContext();
DataDictionary dd = lcc.getDataDictionary();
DependencyManager dm = dd.getDependencyManager();
TransactionController tc = lcc.getTransactionExecute();
/*
** Indicate that we are about to modify the data dictionary.
**
** We tell the data dictionary we're done writing at the end of
** the transaction.
*/
dd.startWriting(lcc);
SchemaDescriptor triggerSd = getSchemaDescriptorForCreate(dd, activation, triggerSchemaName);
if (spsCompSchemaId == null) {
SchemaDescriptor def = lcc.getDefaultSchema();
if (def.getUUID() == null) {
// Descriptor for default schema is stale,
// look it up in the dictionary
def = dd.getSchemaDescriptor(def.getDescriptorName(), tc, false);
}
/*
** It is possible for spsCompSchemaId to be null. For instance,
** the current schema may not have been physically created yet but
** it exists "virtually". In this case, its UUID will have the
** value of null meaning that it is not persistent. e.g.:
**
** CONNECT 'db;create=true' user 'ernie';
** CREATE TABLE bert.t1 (i INT);
** CREATE TRIGGER bert.tr1 AFTER INSERT ON bert.t1
** FOR EACH STATEMENT MODE DB2SQL
** SELECT * FROM SYS.SYSTABLES;
**
** Note that in the above case, the trigger action statement have a
** null compilation schema. A compilation schema with null value
** indicates that the trigger action statement text does not have
** any dependencies with the CURRENT SCHEMA. This means:
**
** o It is safe to compile this statement in any schema since
** there is no dependency with the CURRENT SCHEMA. i.e.: All
** relevent identifiers are qualified with a specific schema.
**
** o The statement cache mechanism can utilize this piece of
** information to enable better statement plan sharing across
** connections in different schemas; thus, avoiding unnecessary
** statement compilation.
*/
if (def != null) spsCompSchemaId = def.getUUID();
}
String tabName;
if (triggerTable != null) {
triggerTableId = triggerTable.getUUID();
tabName = triggerTable.getName();
} else tabName = "with UUID " + triggerTableId;
/* We need to get table descriptor again. We simply can't trust the
* one we got at compile time, the lock on system table was released
* when compile was done, and the table might well have been dropped.
*/
triggerTable = dd.getTableDescriptor(triggerTableId);
if (triggerTable == null) {
throw StandardException.newException(SQLState.LANG_TABLE_NOT_FOUND_DURING_EXECUTION, tabName);
}
/* Lock the table for DDL. Otherwise during our execution, the table
* might be changed, even dropped. Beetle 4269
*/
lockTableForDDL(tc, triggerTable.getHeapConglomerateId(), true);
/* get triggerTable again for correctness, in case it's changed before
* the lock is aquired
*/
triggerTable = dd.getTableDescriptor(triggerTableId);
if (triggerTable == null) {
throw StandardException.newException(SQLState.LANG_TABLE_NOT_FOUND_DURING_EXECUTION, tabName);
}
/*
** Send an invalidate on the table from which
** the triggering event emanates. This it
** to make sure that DML statements on this table
** will be recompiled. Do this before we create
** our trigger spses lest we invalidate them just
** after creating them.
*/
dm.invalidateFor(triggerTable, DependencyManager.CREATE_TRIGGER, lcc);
/*
** Lets get our trigger id up front, we'll use it when
** we create our spses.
*/
UUID tmpTriggerId = dd.getUUIDFactory().createUUID();
actionSPSId = (actionSPSId == null) ? dd.getUUIDFactory().createUUID() : actionSPSId;
DataDescriptorGenerator ddg = dd.getDataDescriptorGenerator();
/*
** Create the trigger descriptor first so the trigger action
** compilation can pick up the relevant trigger especially in
** the case of self triggering.
*/
TriggerDescriptor triggerd =
ddg.newTriggerDescriptor(
triggerSd,
tmpTriggerId,
triggerName,
eventMask,
isBefore,
isRow,
isEnabled,
triggerTable,
whenspsd == null ? null : whenspsd.getUUID(),
actionSPSId,
creationTimestamp == null
? new Timestamp(System.currentTimeMillis())
: creationTimestamp,
referencedCols,
originalActionText,
referencingOld,
referencingNew,
oldReferencingName,
newReferencingName);
dd.addDescriptor(triggerd, triggerSd, DataDictionary.SYSTRIGGERS_CATALOG_NUM, false, tc);
/*
** If we have a WHEN action we create it now.
*/
if (whenText != null) {
whenspsd =
createSPS(
lcc,
ddg,
dd,
tc,
tmpTriggerId,
triggerSd,
whenSPSId,
spsCompSchemaId,
whenText,
true,
triggerTable);
}
/*
** Create the trigger action
*/
actionspsd =
createSPS(
lcc,
ddg,
dd,
tc,
tmpTriggerId,
triggerSd,
actionSPSId,
spsCompSchemaId,
actionText,
false,
triggerTable);
/*
** Make underlying spses dependent on the trigger.
*/
if (whenspsd != null) {
dm.addDependency(triggerd, whenspsd, lcc.getContextManager());
}
dm.addDependency(triggerd, actionspsd, lcc.getContextManager());
dm.addDependency(triggerd, triggerTable, lcc.getContextManager());
dm.addDependency(actionspsd, triggerTable, lcc.getContextManager());
// store trigger's dependency on various privileges in the dependeny system
storeViewTriggerDependenciesOnPrivileges(activation, triggerd);
}