security-admin/src/main/java/org/apache/ranger/common/db/BaseDao.java - ranger - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */

  package org.apache.ranger.common.db;


 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.sql.Connection;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;

 import javax.persistence.EntityManager;
 import javax.persistence.NoResultException;
 import javax.persistence.Query;
 import javax.persistence.Table;
 import javax.persistence.TypedQuery;

 import org.apache.ranger.authorization.hadoop.config.RangerAdminConfig;
 import org.apache.ranger.biz.RangerBizUtil;
 import org.apache.ranger.common.AppConstants;
 import org.apache.ranger.db.RangerDaoManager;
 import org.apache.ranger.db.RangerDaoManagerBase;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 public abstract class BaseDao<T> {
 	private static final Logger logger = LoggerFactory.getLogger(BaseDao.class);
 	private static final String PROP_BATCH_DELETE_BATCH_SIZE    = "ranger.admin.dao.batch.delete.batch.size";
 	private static final int    DEFAULT_BATCH_DELETE_BATCH_SIZE = 1000;
 	private static       int    BATCH_DELETE_BATCH_SIZE;
 	private static final String GDS_TABLES = "x_gds_";

 	static {
 		try {
 			BATCH_DELETE_BATCH_SIZE = RangerAdminConfig.getInstance().getInt(PROP_BATCH_DELETE_BATCH_SIZE, DEFAULT_BATCH_DELETE_BATCH_SIZE);

 			if (BATCH_DELETE_BATCH_SIZE > DEFAULT_BATCH_DELETE_BATCH_SIZE) {
 				logger.warn("Configuration {}={}, which is larger than default value {}", PROP_BATCH_DELETE_BATCH_SIZE, BATCH_DELETE_BATCH_SIZE, DEFAULT_BATCH_DELETE_BATCH_SIZE);
 			}
 		} catch(Exception e) {
 			// When we get the Number format exception due to the invalid value entered into the config file.
 			BATCH_DELETE_BATCH_SIZE = DEFAULT_BATCH_DELETE_BATCH_SIZE;
 		}

 		logger.info(PROP_BATCH_DELETE_BATCH_SIZE + "=" + BATCH_DELETE_BATCH_SIZE);
 	}

 	protected RangerDaoManager daoManager;

 	EntityManager em;

 	protected Class<T> tClass;

 	public BaseDao(RangerDaoManagerBase daoManager) {
 		this.daoManager = (RangerDaoManager) daoManager;
 		this.init(daoManager.getEntityManager());
 	}

 	public BaseDao(RangerDaoManagerBase daoManager, String persistenceContextUnit) {
 		this.daoManager = (RangerDaoManager) daoManager;

 		EntityManager em = this.daoManager.getEntityManager(persistenceContextUnit);

 		this.init(em);
 	}

 	@SuppressWarnings("unchecked")
 	private void init(EntityManager em) {
 		this.em = em;

 		ParameterizedType genericSuperclass = (ParameterizedType) getClass()
 				.getGenericSuperclass();

 		Type type = genericSuperclass.getActualTypeArguments()[0];

 		if (type instanceof ParameterizedType) {
 			this.tClass = (Class<T>) ((ParameterizedType) type).getRawType();
 		} else {
 			this.tClass = (Class<T>) type;
 		}
 	}

 	public EntityManager getEntityManager() {
 		return this.em;
 	}

 	public T create(T obj) {
 		T ret = null;

 		em.persist(obj);
 		if (!RangerBizUtil.isBulkMode()) {
 			em.flush();
 		}
 		ret = obj;
 		return ret;
 	}

 	public List<T> batchCreate(List<T> obj) {
 		List<T> ret = null;

 		for (int n = 0; n < obj.size(); ++n) {
 			em.persist(obj.get(n));
 			if (!RangerBizUtil.isBulkMode() && (n % RangerBizUtil.batchPersistSize == 0)) {
 				em.flush();
 			}
 		}
 		if (!RangerBizUtil.isBulkMode()) {
 			em.flush();
 		}

 		ret = obj;
 		return ret;
 	}

 	public void batchDeleteByIds(String namedQuery, List<Long> ids, String paramName) {
 		if (BATCH_DELETE_BATCH_SIZE <= 0) {
 			getEntityManager()
 				.createNamedQuery(namedQuery, tClass)
 				.setParameter(paramName, ids).executeUpdate();
 		} else {
 			for (int fromIndex = 0; fromIndex < ids.size(); fromIndex += BATCH_DELETE_BATCH_SIZE) {
 				int toIndex = fromIndex + BATCH_DELETE_BATCH_SIZE;

 				if (toIndex > ids.size()) {
 					toIndex = ids.size();
 				}

 				if (logger.isDebugEnabled()) {
 					logger.debug("batchDeleteByIds({}, idCount={}): deleting fromIndex={}, toIndex={}", namedQuery, ids.size(), fromIndex, toIndex);
 				}

 				List<Long> subList = ids.subList(fromIndex, toIndex);

 				getEntityManager()
 						.createNamedQuery(namedQuery, tClass)
 						.setParameter(paramName, subList).executeUpdate();
 			}
 		}
 	}

 	public T update(T obj) {
 		em.merge(obj);
 		if (!RangerBizUtil.isBulkMode()) {
 			em.flush();
 		}
 		return obj;
 	}

 	public boolean remove(Long id) {
 		return remove(getById(id));
 	}

 	public boolean remove(T obj) {
 		if (obj == null) {
 			return true;
 		}
 		if (!em.contains(obj)) {
 			obj = em.merge(obj);
 		}
 		em.remove(obj);
 		if (!RangerBizUtil.isBulkMode()) {
 			em.flush();
 		}
 		return true;
 	}

 	public void flush() {
 		em.flush();
 	}

 	public void clear() {
 		em.clear();
 	}
 	public T create(T obj, boolean flush) {
 		T ret = null;
 		em.persist(obj);
 		if(flush) {
 			em.flush();
 		}
 		ret = obj;
 		return ret;
 	}

 	public T update(T obj, boolean flush) {
 		em.merge(obj);
 		if(flush) {
 			em.flush();
 		}
 		return obj;
 	}

 	public boolean remove(T obj, boolean flush) {
 		if (obj == null) {
 			return true;
 		}
 		em.remove(obj);
 		if(flush) {
 			em.flush();
 		}
 		return true;
 	}

 	public T getById(Long id) {
 		if (id == null) {
 			return null;
 		}
 		T ret = null;
 		try {
 			ret = em.find(tClass, id);
 		} catch (NoResultException e) {
 			return null;
 		}
 		return ret;
 	}

 	public List<T> findByNamedQuery(String namedQuery, String paramName,
 			Object refId) {
 		List<T> ret = new ArrayList<T>();

 		if (namedQuery == null) {
 			return ret;
 		}
 		try {
 			TypedQuery<T> qry = em.createNamedQuery(namedQuery, tClass);
 			qry.setParameter(paramName, refId);
 			ret = qry.getResultList();
 		} catch (NoResultException e) {
 			// ignore
 		}
 		return ret;
 	}

 	public List<T> findByParentId(Long parentId) {
 		String namedQuery = tClass.getSimpleName() + ".findByParentId";
 		return findByNamedQuery(namedQuery, "parentId", parentId);
 	}


 	public List<T> executeQueryInSecurityContext(Class<T> clazz, Query query) {
 		return executeQueryInSecurityContext(clazz, query, true);
 	}

 	@SuppressWarnings("unchecked")
 	public List<T> executeQueryInSecurityContext(Class<T> clazz, Query query,
 			boolean userPrefFilter) {
 		// boolean filterEnabled = false;
 		List<T> rtrnList = null;
 		// filterEnabled = enableVisiblityFilters(clazz, userPrefFilter);

 		rtrnList = query.getResultList();

 		return rtrnList;
 	}

 	public List<Long> getIds(Query query) {
 		return (List<Long>) query.getResultList();
 	}

 	public Long executeCountQueryInSecurityContext(Class<T> clazz, Query query) { //NOPMD
 		return (Long) query.getSingleResult();
 	}

 	public List<T> getAll() {
 		List<T> ret = null;
 		TypedQuery<T> qry = em.createQuery(
 				"SELECT t FROM " + tClass.getSimpleName() + " t", tClass);
 		ret = qry.getResultList();
 		return ret;
 	}

 	public Long getAllCount() {
 		Long ret = null;
 		TypedQuery<Long> qry = em.createQuery(
 				"SELECT count(t) FROM " + tClass.getSimpleName() + " t",
 				Long.class);
 		ret = qry.getSingleResult();
 		return ret;
 	}

 	public void updateSequence(String seqName, long nextValue) {
 		if(RangerBizUtil.getDBFlavor() == AppConstants.DB_FLAVOR_ORACLE) {
 			String[] queries = {
 					"ALTER SEQUENCE " + seqName + " INCREMENT BY " + (nextValue - 1),
 					"select " + seqName + ".nextval from dual",
 					"ALTER SEQUENCE " + seqName + " INCREMENT BY 1 NOCACHE NOCYCLE"
 			};

 			for(String query : queries) {
 				getEntityManager().createNativeQuery(query).executeUpdate();
 			}
 		} else if(RangerBizUtil.getDBFlavor() == AppConstants.DB_FLAVOR_POSTGRES) {
 			String query = "SELECT setval('" + seqName + "', " + nextValue + ")";

 			getEntityManager().createNativeQuery(query).getSingleResult();
 		}

 	}

 	public void setIdentityInsert(boolean identityInsert) {
 		if (RangerBizUtil.getDBFlavor() != AppConstants.DB_FLAVOR_SQLSERVER) {
 			logger.debug("Ignoring BaseDao.setIdentityInsert(). This should be executed if DB flavor is sqlserver.");
 			return;
 		}

 		EntityManager entityMgr = getEntityManager();

 		String identityInsertStr;
 		if (identityInsert) {
 			identityInsertStr = "ON";
 		} else {
 			identityInsertStr = "OFF";
 		}

 		Table table = tClass.getAnnotation(Table.class);

 		if(table == null) {
 			throw new NullPointerException("Required annotation `Table` not found");
 		}

 		String tableName = table.name();

 		try {
 			entityMgr.unwrap(Connection.class).createStatement().execute("SET IDENTITY_INSERT " + tableName + " " + identityInsertStr);
 		} catch (SQLException e) {
 			logger.error("Error while settion identity_insert " + identityInsertStr, e);
 		}
 	}

 	public void updateUserIDReference(String paramName,long oldID) {
 		Table table = tClass.getAnnotation(Table.class);
 		if(table != null) {
 			String tableName = table.name();
 			String updatedValue = tableName.contains(GDS_TABLES) ? "1" : "null";
 			String query = "update " + tableName + " set " + paramName+"=" + updatedValue + " where " +paramName+"=" + oldID;

 			int count=getEntityManager().createNativeQuery(query).executeUpdate();
 			if(count>0){
 				logger.warn(count + " records updated in table '" + tableName + "' with: set " + paramName + "="+ updatedValue + " where " + paramName + "=" + oldID);
 			}
 		}else{
 			logger.warn("Required annotation `Table` not found");
 		}
 	}

 	public String getDBVersion(){
 		String dbVersion="Not Available";
 		int dbFlavor = RangerBizUtil.getDBFlavor();
 		String query ="SELECT 1";
 		try{
 			if(dbFlavor == AppConstants.DB_FLAVOR_MYSQL) {
 				query="SELECT version()";
 				dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
 			}else if(dbFlavor == AppConstants.DB_FLAVOR_ORACLE){
 				query="SELECT banner from v$version where rownum<2";
 				dbVersion = (String)getEntityManager().createNativeQuery(query).getSingleResult();
 			}else if(dbFlavor == AppConstants.DB_FLAVOR_POSTGRES){
 				query="SELECT version()";
 				dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
 			}else if(dbFlavor == AppConstants.DB_FLAVOR_SQLSERVER){
 				query="SELECT @@version";
 				dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
 			}else if(dbFlavor == AppConstants.DB_FLAVOR_SQLANYWHERE){
 				query="SELECT @@version";
 				dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
 			}
 		}catch(Exception ex){
 			logger.error("Error occurred while fetching the DB version.", ex);
 		}
 		return dbVersion;
 	}
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/

	package org.apache.ranger.common.db;



	import java.lang.reflect.ParameterizedType;
	import java.lang.reflect.Type;
	import java.sql.Connection;
	import java.sql.SQLException;
	import java.util.ArrayList;
	import java.util.List;

	import javax.persistence.EntityManager;
	import javax.persistence.NoResultException;
	import javax.persistence.Query;
	import javax.persistence.Table;
	import javax.persistence.TypedQuery;

	import org.apache.ranger.authorization.hadoop.config.RangerAdminConfig;
	import org.apache.ranger.biz.RangerBizUtil;
	import org.apache.ranger.common.AppConstants;
	import org.apache.ranger.db.RangerDaoManager;
	import org.apache.ranger.db.RangerDaoManagerBase;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	public abstract class BaseDao<T> {
	private static final Logger logger = LoggerFactory.getLogger(BaseDao.class);
	private static final String PROP_BATCH_DELETE_BATCH_SIZE = "ranger.admin.dao.batch.delete.batch.size";
	private static final int DEFAULT_BATCH_DELETE_BATCH_SIZE = 1000;
	private static int BATCH_DELETE_BATCH_SIZE;
	private static final String GDS_TABLES = "x_gds_";

	static {
	try {
	BATCH_DELETE_BATCH_SIZE = RangerAdminConfig.getInstance().getInt(PROP_BATCH_DELETE_BATCH_SIZE, DEFAULT_BATCH_DELETE_BATCH_SIZE);

	if (BATCH_DELETE_BATCH_SIZE > DEFAULT_BATCH_DELETE_BATCH_SIZE) {
	logger.warn("Configuration {}={}, which is larger than default value {}", PROP_BATCH_DELETE_BATCH_SIZE, BATCH_DELETE_BATCH_SIZE, DEFAULT_BATCH_DELETE_BATCH_SIZE);
	}
	} catch(Exception e) {
	// When we get the Number format exception due to the invalid value entered into the config file.
	BATCH_DELETE_BATCH_SIZE = DEFAULT_BATCH_DELETE_BATCH_SIZE;
	}

	logger.info(PROP_BATCH_DELETE_BATCH_SIZE + "=" + BATCH_DELETE_BATCH_SIZE);
	}

	protected RangerDaoManager daoManager;

	EntityManager em;

	protected Class<T> tClass;

	public BaseDao(RangerDaoManagerBase daoManager) {
	this.daoManager = (RangerDaoManager) daoManager;
	this.init(daoManager.getEntityManager());
	}

	public BaseDao(RangerDaoManagerBase daoManager, String persistenceContextUnit) {
	this.daoManager = (RangerDaoManager) daoManager;

	EntityManager em = this.daoManager.getEntityManager(persistenceContextUnit);

	this.init(em);
	}

	@SuppressWarnings("unchecked")
	private void init(EntityManager em) {
	this.em = em;

	ParameterizedType genericSuperclass = (ParameterizedType) getClass()
	.getGenericSuperclass();

	Type type = genericSuperclass.getActualTypeArguments()[0];

	if (type instanceof ParameterizedType) {
	this.tClass = (Class<T>) ((ParameterizedType) type).getRawType();
	} else {
	this.tClass = (Class<T>) type;
	}
	}

	public EntityManager getEntityManager() {
	return this.em;
	}

	public T create(T obj) {
	T ret = null;

	em.persist(obj);
	if (!RangerBizUtil.isBulkMode()) {
	em.flush();
	}
	ret = obj;
	return ret;
	}

	public List<T> batchCreate(List<T> obj) {
	List<T> ret = null;

	for (int n = 0; n < obj.size(); ++n) {
	em.persist(obj.get(n));
	if (!RangerBizUtil.isBulkMode() && (n % RangerBizUtil.batchPersistSize == 0)) {
	em.flush();
	}
	}
	if (!RangerBizUtil.isBulkMode()) {
	em.flush();
	}

	ret = obj;
	return ret;
	}

	public void batchDeleteByIds(String namedQuery, List<Long> ids, String paramName) {
	if (BATCH_DELETE_BATCH_SIZE <= 0) {
	getEntityManager()
	.createNamedQuery(namedQuery, tClass)
	.setParameter(paramName, ids).executeUpdate();
	} else {
	for (int fromIndex = 0; fromIndex < ids.size(); fromIndex += BATCH_DELETE_BATCH_SIZE) {
	int toIndex = fromIndex + BATCH_DELETE_BATCH_SIZE;

	if (toIndex > ids.size()) {
	toIndex = ids.size();
	}

	if (logger.isDebugEnabled()) {
	logger.debug("batchDeleteByIds({}, idCount={}): deleting fromIndex={}, toIndex={}", namedQuery, ids.size(), fromIndex, toIndex);
	}

	List<Long> subList = ids.subList(fromIndex, toIndex);

	getEntityManager()
	.createNamedQuery(namedQuery, tClass)
	.setParameter(paramName, subList).executeUpdate();
	}
	}
	}

	public T update(T obj) {
	em.merge(obj);
	if (!RangerBizUtil.isBulkMode()) {
	em.flush();
	}
	return obj;
	}

	public boolean remove(Long id) {
	return remove(getById(id));
	}

	public boolean remove(T obj) {
	if (obj == null) {
	return true;
	}
	if (!em.contains(obj)) {
	obj = em.merge(obj);
	}
	em.remove(obj);
	if (!RangerBizUtil.isBulkMode()) {
	em.flush();
	}
	return true;
	}

	public void flush() {
	em.flush();
	}

	public void clear() {
	em.clear();
	}
	public T create(T obj, boolean flush) {
	T ret = null;
	em.persist(obj);
	if(flush) {
	em.flush();
	}
	ret = obj;
	return ret;
	}

	public T update(T obj, boolean flush) {
	em.merge(obj);
	if(flush) {
	em.flush();
	}
	return obj;
	}

	public boolean remove(T obj, boolean flush) {
	if (obj == null) {
	return true;
	}
	em.remove(obj);
	if(flush) {
	em.flush();
	}
	return true;
	}

	public T getById(Long id) {
	if (id == null) {
	return null;
	}
	T ret = null;
	try {
	ret = em.find(tClass, id);
	} catch (NoResultException e) {
	return null;
	}
	return ret;
	}

	public List<T> findByNamedQuery(String namedQuery, String paramName,
	Object refId) {
	List<T> ret = new ArrayList<T>();

	if (namedQuery == null) {
	return ret;
	}
	try {
	TypedQuery<T> qry = em.createNamedQuery(namedQuery, tClass);
	qry.setParameter(paramName, refId);
	ret = qry.getResultList();
	} catch (NoResultException e) {
	// ignore
	}
	return ret;
	}

	public List<T> findByParentId(Long parentId) {
	String namedQuery = tClass.getSimpleName() + ".findByParentId";
	return findByNamedQuery(namedQuery, "parentId", parentId);
	}


	public List<T> executeQueryInSecurityContext(Class<T> clazz, Query query) {
	return executeQueryInSecurityContext(clazz, query, true);
	}

	@SuppressWarnings("unchecked")
	public List<T> executeQueryInSecurityContext(Class<T> clazz, Query query,
	boolean userPrefFilter) {
	// boolean filterEnabled = false;
	List<T> rtrnList = null;
	// filterEnabled = enableVisiblityFilters(clazz, userPrefFilter);

	rtrnList = query.getResultList();

	return rtrnList;
	}

	public List<Long> getIds(Query query) {
	return (List<Long>) query.getResultList();
	}

	public Long executeCountQueryInSecurityContext(Class<T> clazz, Query query) { //NOPMD
	return (Long) query.getSingleResult();
	}

	public List<T> getAll() {
	List<T> ret = null;
	TypedQuery<T> qry = em.createQuery(
	"SELECT t FROM " + tClass.getSimpleName() + " t", tClass);
	ret = qry.getResultList();
	return ret;
	}

	public Long getAllCount() {
	Long ret = null;
	TypedQuery<Long> qry = em.createQuery(
	"SELECT count(t) FROM " + tClass.getSimpleName() + " t",
	Long.class);
	ret = qry.getSingleResult();
	return ret;
	}

	public void updateSequence(String seqName, long nextValue) {
	if(RangerBizUtil.getDBFlavor() == AppConstants.DB_FLAVOR_ORACLE) {
	String[] queries = {
	"ALTER SEQUENCE " + seqName + " INCREMENT BY " + (nextValue - 1),
	"select " + seqName + ".nextval from dual",
	"ALTER SEQUENCE " + seqName + " INCREMENT BY 1 NOCACHE NOCYCLE"
	};

	for(String query : queries) {
	getEntityManager().createNativeQuery(query).executeUpdate();
	}
	} else if(RangerBizUtil.getDBFlavor() == AppConstants.DB_FLAVOR_POSTGRES) {
	String query = "SELECT setval('" + seqName + "', " + nextValue + ")";

	getEntityManager().createNativeQuery(query).getSingleResult();
	}

	}

	public void setIdentityInsert(boolean identityInsert) {
	if (RangerBizUtil.getDBFlavor() != AppConstants.DB_FLAVOR_SQLSERVER) {
	logger.debug("Ignoring BaseDao.setIdentityInsert(). This should be executed if DB flavor is sqlserver.");
	return;
	}

	EntityManager entityMgr = getEntityManager();

	String identityInsertStr;
	if (identityInsert) {
	identityInsertStr = "ON";
	} else {
	identityInsertStr = "OFF";
	}

	Table table = tClass.getAnnotation(Table.class);

	if(table == null) {
	throw new NullPointerException("Required annotation `Table` not found");
	}

	String tableName = table.name();

	try {
	entityMgr.unwrap(Connection.class).createStatement().execute("SET IDENTITY_INSERT " + tableName + " " + identityInsertStr);
	} catch (SQLException e) {
	logger.error("Error while settion identity_insert " + identityInsertStr, e);
	}
	}

	public void updateUserIDReference(String paramName,long oldID) {
	Table table = tClass.getAnnotation(Table.class);
	if(table != null) {
	String tableName = table.name();
	String updatedValue = tableName.contains(GDS_TABLES) ? "1" : "null";
	String query = "update " + tableName + " set " + paramName+"=" + updatedValue + " where " +paramName+"=" + oldID;

	int count=getEntityManager().createNativeQuery(query).executeUpdate();
	if(count>0){
	logger.warn(count + " records updated in table '" + tableName + "' with: set " + paramName + "="+ updatedValue + " where " + paramName + "=" + oldID);
	}
	}else{
	logger.warn("Required annotation `Table` not found");
	}
	}

	public String getDBVersion(){
	String dbVersion="Not Available";
	int dbFlavor = RangerBizUtil.getDBFlavor();
	String query ="SELECT 1";
	try{
	if(dbFlavor == AppConstants.DB_FLAVOR_MYSQL) {
	query="SELECT version()";
	dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
	}else if(dbFlavor == AppConstants.DB_FLAVOR_ORACLE){
	query="SELECT banner from v$version where rownum<2";
	dbVersion = (String)getEntityManager().createNativeQuery(query).getSingleResult();
	}else if(dbFlavor == AppConstants.DB_FLAVOR_POSTGRES){
	query="SELECT version()";
	dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
	}else if(dbFlavor == AppConstants.DB_FLAVOR_SQLSERVER){
	query="SELECT @@version";
	dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
	}else if(dbFlavor == AppConstants.DB_FLAVOR_SQLANYWHERE){
	query="SELECT @@version";
	dbVersion=(String) getEntityManager().createNativeQuery(query).getSingleResult();
	}
	}catch(Exception ex){
	logger.error("Error occurred while fetching the DB version.", ex);
	}
	return dbVersion;
	}
	}