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package oracle.toplink.essentials.sequencing;
import oracle.toplink.essentials.queryframework.*;
import oracle.toplink.essentials.internal.databaseaccess.DatabasePlatform;
import oracle.toplink.essentials.internal.helper.Helper;
import oracle.toplink.essentials.exceptions.ValidationException;
/**
* <p>
* <b>Purpose</b>: Define a database's native sequencing mechanism.
* <p>
* <b>Description</b>
* Many databases have built in support for sequencing.
* This can be a SEQUENCE object such as in Oracle,
* or a auto-incrementing column such as the IDENTITY field in Sybase.
* For an auto-incrementing column the preallocation size is always 1.
* For a SEQUENCE object the preallocation size must match the SEQUENCE objects "increment by".
*/
public class NativeSequence extends QuerySequence {
/**
* true indicates that identity should be used - if the platform supports identity.
* false indicates that sequence objects should be used - if the platform supports sequence objects.
*/
protected boolean shouldUseIdentityIfPlatformSupports = true;
public NativeSequence() {
super();
setShouldSkipUpdate(true);
}
public NativeSequence(boolean shouldUseIdentityIfPlatformSupports) {
super();
setShouldSkipUpdate(true);
setShouldUseIdentityIfPlatformSupports(shouldUseIdentityIfPlatformSupports);
}
/**
* Create a new sequence with the name.
*/
public NativeSequence(String name) {
super(name);
setShouldSkipUpdate(true);
}
public NativeSequence(String name, boolean shouldUseIdentityIfPlatformSupports) {
super(name);
setShouldSkipUpdate(true);
setShouldUseIdentityIfPlatformSupports(shouldUseIdentityIfPlatformSupports);
}
/**
* Create a new sequence with the name and sequence pre-allocation size.
*/
public NativeSequence(String name, int size) {
super(name, size);
setShouldSkipUpdate(true);
}
public NativeSequence(String name, int size, boolean shouldUseIdentityIfPlatformSupports) {
super(name, size);
setShouldSkipUpdate(true);
setShouldUseIdentityIfPlatformSupports(shouldUseIdentityIfPlatformSupports);
}
public NativeSequence(String name, int size, int initialValue) {
super(name, size, initialValue);
setShouldSkipUpdate(true);
}
public NativeSequence(String name, int size, int initialValue, boolean shouldUseIdentityIfPlatformSupports) {
super(name, size, initialValue);
setShouldSkipUpdate(true);
setShouldUseIdentityIfPlatformSupports(shouldUseIdentityIfPlatformSupports);
}
public void setShouldUseIdentityIfPlatformSupports(boolean shouldUseIdentityIfPlatformSupports) {
this.shouldUseIdentityIfPlatformSupports = shouldUseIdentityIfPlatformSupports;
}
public boolean shouldUseIdentityIfPlatformSupports() {
return shouldUseIdentityIfPlatformSupports;
}
public boolean equals(Object obj) {
if (obj instanceof NativeSequence) {
return equalNameAndSize(this, (NativeSequence)obj);
} else {
return false;
}
}
/**
* INTERNAL:
*/
protected ValueReadQuery buildSelectQuery() {
if(this.shouldAcquireValueAfterInsert()) {
return ((DatabasePlatform)getDatasourcePlatform()).buildSelectQueryForIdentity();
} else {
return ((DatabasePlatform)getDatasourcePlatform()).buildSelectQueryForSequenceObject();
}
}
/**
* INTERNAL:
*/
protected ValueReadQuery buildSelectQuery(String seqName, Integer size) {
if(this.shouldAcquireValueAfterInsert()) {
return ((DatabasePlatform)getDatasourcePlatform()).buildSelectQueryForIdentity(seqName, size);
} else {
return ((DatabasePlatform)getDatasourcePlatform()).buildSelectQueryForSequenceObject(seqName, size);
}
}
/**
* INTERNAL:
*/
public void onConnect() {
DatabasePlatform dbPlatform = null;
try {
dbPlatform = (DatabasePlatform)getDatasourcePlatform();
} catch (ClassCastException ex) {
if (getSelectQuery() == null) {
throw ValidationException.platformDoesNotSupportSequence(getName(), Helper.getShortClassName(getDatasourcePlatform()), Helper.getShortClassName(this));
}
}
if (!dbPlatform.supportsNativeSequenceNumbers() && (getSelectQuery() == null)) {
throw ValidationException.platformDoesNotSupportSequence(getName(), Helper.getShortClassName(getDatasourcePlatform()), Helper.getShortClassName(this));
}
// Set shouldAcquireValueAfterInsert flag: identity -> true; sequence objects -> false.
if(dbPlatform.supportsIdentity() && shouldUseIdentityIfPlatformSupports()) {
// identity is both supported by platform and desired by the NativeSequence
setShouldAcquireValueAfterInsert(true);
} else if(dbPlatform.supportsSequenceObjects() && !shouldUseIdentityIfPlatformSupports()) {
// sequence objects is both supported by platform and desired by the NativeSequence
setShouldAcquireValueAfterInsert(false);
} else {
if(dbPlatform.supportsNativeSequenceNumbers()) {
// platform support contradicts to NativeSequence setting - go with platform supported choice.
// platform must support either identity or sequence objects (otherwise ValidationException would've been thrown earlier),
// therefore here dbPlatform.supportsIdentity() == !dbPlatform.supportsSequenceObjects().
setShouldAcquireValueAfterInsert(dbPlatform.supportsIdentity());
}
}
setShouldUseTransaction(dbPlatform.shouldNativeSequenceUseTransaction());
super.onConnect();
}
/**
* INTERNAL:
*/
public void onDisconnect() {
setShouldAcquireValueAfterInsert(false);
setShouldUseTransaction(false);
super.onDisconnect();
}
}