#350 - ENH: Add @History findVersions() query ... returning historic versions for a given bean using history view

src/main/java/com/avaje/ebean/EbeanServer.java

@@ -904,6 +904,15 @@ public interface EbeanServer {
    */
   <T> void findEachWhile(Query<T> query, QueryEachWhileConsumer<T> consumer, Transaction transaction);
 
+  /**
+   * Return versions of a @History entity bean.
+   * <p>
+   *   Generally this query is expected to be a find by id or unique predicates query.
+   *   It will execute the query against the history returning the versions of the bean.
+   * </p>
+   */
+  <T> List<Version<T>> findVersions(Query<T> query, Transaction transaction);
+
   /**
    * Execute a query returning a list of beans.
    * <p>

src/main/java/com/avaje/ebean/ExpressionList.java

@@ -235,6 +235,15 @@ public interface ExpressionList<T> extends Serializable {
    */
   PagedList<T> findPagedList(int pageIndex, int pageSize);
 
+  /**
+   * Return versions of a @History entity bean.
+   * <p>
+   *   Generally this query is expected to be a find by id or unique predicates query.
+   *   It will execute the query against the history returning the versions of the bean.
+   * </p>
+   */
+  List<Version<T>> findVersions();
+
   /**
    * Add some filter predicate expressions to the many property.
    */

src/main/java/com/avaje/ebean/Query.java

@@ -720,6 +720,15 @@ public interface Query<T> extends Serializable {
   @Nullable
   T findUnique();
 
+  /**
+   * Return versions of a @History entity bean.
+   * <p>
+   *   Generally this query is expected to be a find by id or unique predicates query.
+   *   It will execute the query against the history returning the versions of the bean.
+   * </p>
+   */
+  List<Version<T>> findVersions();
+
   /**
    * Return the count of entities this query should return.
    * <p>

src/main/java/com/avaje/ebean/Version.java

@@ -0,0 +1,81 @@
+package com.avaje.ebean;
+
+import java.sql.Timestamp;
+
+/**
+ * Wraps a version of a @History bean.
+ */
+public class Version<T> {
+
+  /**
+   * The version of the bean.
+   */
+  T bean;
+
+  /**
+   * The effective start date time of this version.
+   */
+  Timestamp start;
+
+  /**
+   * The effective end date time of this version.
+   */
+  Timestamp end;
+
+  /**
+   * Construct with bean and an effective date time range.
+   */
+  public Version(T bean, Timestamp start, Timestamp end) {
+    this.bean = bean;
+    this.start = start;
+    this.end = end;
+  }
+
+  /**
+   * Default constructor - useful for JSON tools such as Jackson.
+   */
+  public Version() {
+  }
+
+  /**
+   * Return the bean instance for this version.
+   */
+  public T getBean() {
+    return bean;
+  }
+
+  /**
+   * Set the bean instance for this version.
+   */
+  public void setBean(T bean) {
+    this.bean = bean;
+  }
+
+  /**
+   * Return the effective start date time of this version.
+   */
+  public Timestamp getStart() {
+    return start;
+  }
+
+  /**
+   * Set the effective start date time of this version.
+   */
+  public void setStart(Timestamp start) {
+    this.start = start;
+  }
+
+  /**
+   * Return the effective end date time of this version.
+   */
+  public Timestamp getEnd() {
+    return end;
+  }
+
+  /**
+   * Set the effective end date time of this version.
+   */
+  public void setEnd(Timestamp end) {
+    this.end = end;
+  }
+}

src/main/java/com/avaje/ebean/config/dbplatform/DatabasePlatform.java

@@ -80,6 +80,11 @@ public class DatabasePlatform {
    */
   protected DbIdentity dbIdentity = new DbIdentity();
 
+  /**
+   * The history support for this database platform.
+   */
+  protected DbHistorySupport historySupport;
+
   /** 
    * The JDBC type to map booleans to (by default). 
    */
@@ -215,6 +220,20 @@ public class DatabasePlatform {
     this.dbEncrypt = dbEncrypt;
   }
 
+  /**
+   * Return the history support for this database platform.
+   */
+  public DbHistorySupport getHistorySupport() {
+    return historySupport;
+  }
+
+  /**
+   * Set the history support for this database platform.
+   */
+  public void setHistorySupport(DbHistorySupport historySupport) {
+    this.historySupport = historySupport;
+  }
+
   /**
    * Return the mapping of JDBC to DB types.
    * 
@@ -442,17 +461,6 @@ public class DatabasePlatform {
     return disallowBatchOnCascade;
   }
 
-  /**
-   * Return the 'as of' predicate added for the given table alias.
-   *
-   * @param asOfTableAlias The table alias this predicate is added for
-   * @param asOfSysPeriod  The name of the 'sys_period' column used for effective date time range.
-   * @return The predicate containing a single ? bind parameter which will be bound to the 'as at' timestamp value
-   */
-  public String getAsOfPredicate(String asOfTableAlias, String asOfSysPeriod) {
-    throw new RuntimeException("AsOf query not support of this database platform yet");
-  }
-
   /**
    * Generate and return the create sequence DDL.
    */

src/main/java/com/avaje/ebean/config/dbplatform/DbHistorySupport.java

@@ -0,0 +1,33 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * History support for the database platform.
+ */
+public interface DbHistorySupport {
+
+  /**
+   * Return the 'as of' predicate added for the given table alias.
+   *
+   * @param tableAlias The table alias this predicate is added for
+   * @param sysPeriod  The name of the 'sys_period' column used for effective date time range.
+   * @return The predicate containing a single ? bind parameter which will be bound to the 'as at' timestamp value
+   */
+  String getAsOfPredicate(String tableAlias, String sysPeriod);
+
+  /**
+   * Return the column for the system period lower bound that will be included in findVersions() queries.
+   *
+   * @param tableAlias the table alias which will typically be 't0'
+   * @param sysPeriod the name of the sys_period column
+   */
+  String getSysPeriodLower(String tableAlias, String sysPeriod);
+
+  /**
+   * Return the column for the system period upper bound that will be included in findVersions() queries.
+   *
+   * @param tableAlias the table alias which will typically be 't0'
+   * @param sysPeriod the name of the sys_period column
+   */
+  String getSysPeriodUpper(String tableAlias, String sysPeriod);
+
+}

src/main/java/com/avaje/ebean/config/dbplatform/Postgres8Platform.java

@@ -21,6 +21,7 @@ public class Postgres8Platform extends DatabasePlatform {
     this.clobDbType = Types.VARCHAR;
 
     this.dbEncrypt = new PostgresDbEncrypt();
+    this.historySupport = new PostgresHistorySupport();
 
     this.dbIdentity.setSupportsGetGeneratedKeys(false);
     this.dbIdentity.setIdType(IdType.SEQUENCE);
@@ -47,30 +48,13 @@ public class Postgres8Platform extends DatabasePlatform {
 
     dbDdlSyntax.setDropTableCascade("cascade");
     dbDdlSyntax.setDropIfExists("if exists");
-
-  }
-
-  /**
-   * Build and return the 'as of' predicate for a given table alias.
-   * <p>
-   * Each @History entity involved in the query has this predicate added using the related table alias.
-   * </p>
-   */
-  public String getAsOfPredicate(String asOfTableAlias, String asOfSysPeriod) {
-
-    // for Postgres we are using the 'timestamp with timezone range' data type
-    // as our sys_period column so hence the predicate below
-    StringBuilder sb = new StringBuilder(40);
-    sb.append(asOfTableAlias).append(".").append(asOfSysPeriod).append(" @> ?::timestamptz");
-    return sb.toString();
   }
 
   /**
    * Create a Postgres specific sequence IdGenerator.
    */
   @Override
-  public IdGenerator createSequenceIdGenerator(BackgroundExecutor be, DataSource ds,
-      String seqName, int batchSize) {
+  public IdGenerator createSequenceIdGenerator(BackgroundExecutor be, DataSource ds, String seqName, int batchSize) {
 
     return new PostgresSequenceIdGenerator(be, ds, seqName, batchSize);
   }

src/main/java/com/avaje/ebean/config/dbplatform/PostgresHistorySupport.java

@@ -0,0 +1,33 @@
+package com.avaje.ebean.config.dbplatform;
+
+/**
+ * Postgres support for history features.
+ */
+public class PostgresHistorySupport implements DbHistorySupport {
+
+  /**
+   * Build and return the 'as of' predicate for a given table alias.
+   * <p>
+   * Each @History entity involved in the query has this predicate added using the related table alias.
+   * </p>
+   */
+  @Override
+  public String getAsOfPredicate(String asOfTableAlias, String asOfSysPeriod) {
+
+    // for Postgres we are using the 'timestamp with timezone range' data type
+    // as our sys_period column so hence the predicate below
+    StringBuilder sb = new StringBuilder(40);
+    sb.append(asOfTableAlias).append(".").append(asOfSysPeriod).append(" @> ?::timestamptz");
+    return sb.toString();
+  }
+
+  @Override
+  public String getSysPeriodLower(String tableAlias, String sysPeriod) {
+    return "lower("+tableAlias+"."+sysPeriod+")";
+  }
+
+  @Override
+  public String getSysPeriodUpper(String tableAlias, String sysPeriod) {
+    return "upper("+tableAlias+"."+sysPeriod+")";
+  }
+}

src/main/java/com/avaje/ebean/config/dbplatform/PostgresPlatform.java

@@ -27,6 +27,7 @@ public class PostgresPlatform extends DatabasePlatform {
     this.clobDbType = Types.VARCHAR;
 
     this.dbEncrypt = new PostgresDbEncrypt();
+    this.historySupport = new PostgresHistorySupport();
 
     // Use Identity and getGeneratedKeys
     this.dbIdentity.setIdType(IdType.IDENTITY);
@@ -57,23 +58,8 @@ public class PostgresPlatform extends DatabasePlatform {
 
     dbDdlSyntax.setDropTableCascade("cascade");
     dbDdlSyntax.setDropIfExists("if exists");
-
   }
 
-  /**
-   * Build and return the 'as of' predicate for a given table alias.
-   * <p>
-   * Each @History entity involved in the query has this predicate added using the related table alias.
-   * </p>
-   */
-  public String getAsOfPredicate(String asOfTableAlias, String asOfSysPeriod) {
-
-    // for Postgres we are using the 'timestamp with timezone range' data type
-    // as our sys_period column so hence the predicate below
-    StringBuilder sb = new StringBuilder(40);
-    sb.append(asOfTableAlias).append(".").append(asOfSysPeriod).append(" @> ?::timestamptz");
-    return sb.toString();
-  }
 
   /**
    * Create a Postgres specific sequence IdGenerator.

src/main/java/com/avaje/ebeaninternal/server/core/DefaultServer.java

@@ -1355,6 +1355,19 @@ public final class DefaultServer implements SpiEbeanServer {
     }
   }
 
+  @Override
+  public <T> List<Version<T>> findVersions(Query<T> query, Transaction transaction) {
+
+    SpiOrmQueryRequest<T> request = createQueryRequest(Type.LIST, query, transaction);
+    try {
+      request.initTransIfRequired();
+      return request.findVersions();
+
+    } finally {
+      request.endTransIfRequired();
+    }
+  }
+
   @SuppressWarnings("unchecked")
   public <T> List<T> findList(Query<T> query, Transaction t) {
 

src/main/java/com/avaje/ebeaninternal/server/core/OrmQueryEngine.java

@@ -1,38 +1,42 @@
 package com.avaje.ebeaninternal.server.core;
 
 import com.avaje.ebean.QueryIterator;
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.BeanCollection;
 import com.avaje.ebeaninternal.api.BeanIdList;
 
+import java.util.List;
+
 /**
  * The Object Relational query execution API.
  */
 public interface OrmQueryEngine {
 
-	/**
-	 * Execute the 'find by id' query returning a single bean.
-	 */
-    public <T> T findId(OrmQueryRequest<T> request);
+  /**
+   * Execute the 'find by id' query returning a single bean.
+   */
+  <T> T findId(OrmQueryRequest<T> request);
 
-    /**
-     * Execute the findList, findSet, findMap query returning an appropriate BeanCollection.
-     */
-    public <T> BeanCollection<T> findMany(OrmQueryRequest<T> request);
+  /**
+   * Execute the findList, findSet, findMap query returning an appropriate BeanCollection.
+   */
+  <T> BeanCollection<T> findMany(OrmQueryRequest<T> request);
 
-    /**
-     * Execute the query using a QueryIterator.
-     */
-    public <T> QueryIterator<T> findIterate(OrmQueryRequest<T> request);
-    
-    /**
-     * Execute the row count query.
-     */
-    public <T> int findRowCount(OrmQueryRequest<T> request);
-    
-    /**
-     * Execute the find id's query.
-     */
-    public <T> BeanIdList findIds(OrmQueryRequest<T> request);
+  <T> List<Version<T>> findVersions(OrmQueryRequest<T> request);
 
+  /**
+   * Execute the query using a QueryIterator.
+   */
+  <T> QueryIterator<T> findIterate(OrmQueryRequest<T> request);
+
+  /**
+   * Execute the row count query.
+   */
+  <T> int findRowCount(OrmQueryRequest<T> request);
+
+  /**
+   * Execute the find id's query.
+   */
+  <T> BeanIdList findIds(OrmQueryRequest<T> request);
 
 }

src/main/java/com/avaje/ebeaninternal/server/core/OrmQueryRequest.java

@@ -271,6 +271,10 @@ public final class OrmQueryRequest<T> extends BeanRequest implements BeanQueryRe
     return (List<T>) queryEngine.findMany(this);
   }
 
+  public List<Version<T>> findVersions() {
+    return queryEngine.findVersions(this);
+  }
+
   /**
    * Execute the query as findSet.
    */

src/main/java/com/avaje/ebeaninternal/server/core/SpiOrmQueryRequest.java

@@ -3,6 +3,7 @@ package com.avaje.ebeaninternal.server.core;
 import com.avaje.ebean.QueryEachConsumer;
 import com.avaje.ebean.QueryEachWhileConsumer;
 import com.avaje.ebean.QueryIterator;
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.BeanCollection;
 import com.avaje.ebeaninternal.api.SpiQuery;
 import com.avaje.ebeaninternal.server.deploy.BeanDescriptor;
@@ -76,6 +77,11 @@ public interface SpiOrmQueryRequest<T> {
    */
   QueryIterator<T> findIterate();
 
+  /**
+   * Execute the finVersions() query.
+   */
+  List<Version<T>> findVersions();
+
   /**
    * Execute the query as findList.
    */

src/main/java/com/avaje/ebeaninternal/server/deploy/DbSqlContext.java

@@ -114,4 +114,10 @@ public interface DbSqlContext {
 
   String getRelativePrefix(String propName);
 
+  /**
+   * Append the lower and upper bound columns into the select clause
+   * for findVersions() queries.
+   */
+  void appendHistorySysPeriod();
+
 }

src/main/java/com/avaje/ebeaninternal/server/expression/JunctionExpression.java

@@ -223,6 +223,11 @@ abstract class JunctionExpression<T> implements Junction<T>, SpiExpression, Expr
     return exprList.asOf(asOf);
   }
 
+  @Override
+  public List<Version<T>> findVersions() {
+    return exprList.findVersions();
+  }
+
   @Override
   public Query<T> apply(PathProperties pathProperties) {
     return exprList.apply(pathProperties);

src/main/java/com/avaje/ebeaninternal/server/query/CQuery.java

@@ -1,6 +1,7 @@
 package com.avaje.ebeaninternal.server.query;
 
 import com.avaje.ebean.QueryIterator;
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.*;
 import com.avaje.ebeaninternal.api.SpiQuery;
 import com.avaje.ebeaninternal.api.SpiQuery.Mode;
@@ -22,6 +23,8 @@ import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
@@ -479,6 +482,30 @@ public class CQuery<T> implements DbReadContext, CancelableQuery {
     }
   }
 
+  /**
+   * Read version beans and their effective dates.
+   */
+  public List<Version<T>> readVersions() throws SQLException {
+
+    List<Version<T>> versionList = new ArrayList<Version<T>>();
+
+    Version version;
+    while ((version = readNextVersion()) != null) {
+      versionList.add(version);
+    }
+
+    updateExecutionStatistics();
+    return versionList;
+  }
+
+  private Version readNextVersion() throws SQLException {
+
+    if (moveToNextRow()) {
+      return rootNode.loadVersion(this);
+    }
+    return null;
+  }
+
   public BeanCollection<T> readCollection() throws SQLException {
 
     while (hasNext()) {

src/main/java/com/avaje/ebeaninternal/server/query/CQueryBuilder.java

@@ -5,6 +5,7 @@ import com.avaje.ebean.RawSql.ColumnMapping;
 import com.avaje.ebean.RawSql.ColumnMapping.Column;
 import com.avaje.ebean.RawSqlBuilder;
 import com.avaje.ebean.config.dbplatform.DatabasePlatform;
+import com.avaje.ebean.config.dbplatform.DbHistorySupport;
 import com.avaje.ebean.config.dbplatform.SqlLimitRequest;
 import com.avaje.ebean.config.dbplatform.SqlLimitResponse;
 import com.avaje.ebean.config.dbplatform.SqlLimiter;
@@ -48,8 +49,10 @@ public class CQueryBuilder implements Constants {
   private final Map<String,String> asOfTableMapping;
 
   private final String asOfSysPeriod;
+  private final DbHistorySupport dbHistorySupport;
+  private final CQueryHistorySupport historySupport;
 
-  private DatabasePlatform dbPlatform;
+  private final DatabasePlatform dbPlatform;
 
   /**
    * Create the SqlGenSelect.
@@ -63,6 +66,8 @@ public class CQueryBuilder implements Constants {
     this.columnAliasPrefix = dbPlatform.getColumnAliasPrefix();
     this.sqlSelectBuilder = new RawSqlSelectClauseBuilder(dbPlatform, binder);
 
+    this.dbHistorySupport = dbPlatform.getHistorySupport();
+    this.historySupport = new CQueryHistorySupport(dbHistorySupport, asOfTableMapping, asOfSysPeriod);
     this.sqlLimiter = dbPlatform.getSqlLimiter();
     this.rawSqlHandler = new CQueryBuilderRawSql(sqlLimiter, dbPlatform);
 
@@ -111,8 +116,7 @@ public class CQueryBuilder implements Constants {
     // use RawSql or generated Sql
     predicates.prepare(true);
 
-    Map<String,String> asOfMap = query.isAsOfQuery() ? asOfTableMapping : null;
-    SqlTree sqlTree = createSqlTree(request, predicates, asOfMap);
+    SqlTree sqlTree = createSqlTree(request, predicates, getHistorySupport(query));
     SqlLimitResponse s = buildSql(null, request, predicates, sqlTree);
     String sql = s.getSql();
 
@@ -123,6 +127,13 @@ public class CQueryBuilder implements Constants {
     return new CQueryFetchIds(request, predicates, sql);
   }
 
+  /**
+   * Return the history support if this query needs it (is a 'as of' type query).
+   */
+  private <T> CQueryHistorySupport getHistorySupport(SpiQuery<T> query) {
+    return query.getTemporalMode() != SpiQuery.TemporalMode.CURRENT ? historySupport : null;
+  }
+
   /**
    * Build the row count query.
    */
@@ -164,8 +175,7 @@ public class CQueryBuilder implements Constants {
 
     predicates.prepare(true);
 
-    Map<String,String> asOfMap = query.isAsOfQuery() ? asOfTableMapping : null;
-    SqlTree sqlTree = createSqlTree(request, predicates, asOfMap);
+    SqlTree sqlTree = createSqlTree(request, predicates, getHistorySupport(query));
     SqlLimitResponse s = buildSql(sqlSelect, request, predicates, sqlTree);
     String sql = s.getSql();
     if (hasMany || query.isRawSql()) {
@@ -215,8 +225,7 @@ public class CQueryBuilder implements Constants {
     // Build the tree structure that represents the query.
     SpiQuery<T> query = request.getQuery();
 
-    Map<String,String> asOfMap = query.isAsOfQuery() ? asOfTableMapping : null;
-    SqlTree sqlTree = createSqlTree(request, predicates, asOfMap);
+    SqlTree sqlTree = createSqlTree(request, predicates, getHistorySupport(query));
     if (query.isAsOfQuery()) {
       sqlTree.addAsOfTableAlias(query);
     }
@@ -249,13 +258,13 @@ public class CQueryBuilder implements Constants {
    * order by clauses that are not already included for the select clause.
    * </p>
    */
-  private SqlTree createSqlTree(OrmQueryRequest<?> request, CQueryPredicates predicates, Map<String,String> withHistoryTables) {
+  private SqlTree createSqlTree(OrmQueryRequest<?> request, CQueryPredicates predicates, CQueryHistorySupport historySupport) {
 
     if (request.isRawSql()) {
       return createRawSqlSqlTree(request, predicates);
     }
 
-    return new SqlTreeBuilder(tableAliasPlaceHolder, columnAliasPrefix, request, predicates, withHistoryTables).build();
+    return new SqlTreeBuilder(tableAliasPlaceHolder, columnAliasPrefix, request, predicates, historySupport).build();
   }
 
   private SqlTree createRawSqlSqlTree(OrmQueryRequest<?> request, CQueryPredicates predicates) {
@@ -418,7 +427,7 @@ public class CQueryBuilder implements Constants {
         if (i > 0) {
           sb.append(" and ");
         }
-        sb.append(dbPlatform.getAsOfPredicate(asOfTableAlias.get(i), asOfSysPeriod));
+        sb.append(dbHistorySupport.getAsOfPredicate(asOfTableAlias.get(i), asOfSysPeriod));
       }
     }
 

src/main/java/com/avaje/ebeaninternal/server/query/CQueryEngine.java

@@ -1,8 +1,10 @@
 package com.avaje.ebeaninternal.server.query;
 
 import java.sql.SQLException;
+import java.util.List;
 import java.util.Map;
 
+import com.avaje.ebean.Version;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -154,6 +156,35 @@ public class CQueryEngine {
     }
   }
 
+  /**
+   * Execute the find versions query returning version beans.
+   */
+  public <T> List<Version<T>> findVersions(OrmQueryRequest<T> request) {
+
+    CQuery<T> cquery = queryBuilder.buildQuery(request);
+    try {
+      cquery.prepareBindExecuteQuery();
+      if (request.isLogSql()) {
+        logSql(cquery);
+      }
+
+      List<Version<T>> versions = cquery.readVersions();
+      if (request.isLogSummary()) {
+        logFindManySummary(cquery);
+      }
+
+      return versions;
+
+    } catch (SQLException e) {
+      throw cquery.createPersistenceException(e);
+
+    } finally {
+      if (cquery != null) {
+        cquery.close();
+      }
+    }
+  }
+
   /**
    * Find a list/map/set of beans.
    */

src/main/java/com/avaje/ebeaninternal/server/query/CQueryHistorySupport.java

@@ -0,0 +1,47 @@
+package com.avaje.ebeaninternal.server.query;
+
+import com.avaje.ebean.config.dbplatform.DbHistorySupport;
+
+import java.util.Map;
+
+/**
+ * Helper to support history functions.
+ */
+public class CQueryHistorySupport {
+
+  /**
+   * The DB specific support.
+   */
+  private final DbHistorySupport dbHistorySupport;
+
+  /**
+   * The mapping of base tables to their matching 'with history' views.
+   */
+  private final Map<String,String> asOfTableMap;
+
+  /**
+   * The sys period column.
+   */
+  private final String asOfSysPeriod;
+
+  public CQueryHistorySupport(DbHistorySupport dbHistorySupport, Map<String, String> asOfTableMap, String asOfSysPeriod) {
+    this.dbHistorySupport = dbHistorySupport;
+    this.asOfTableMap = asOfTableMap;
+    this.asOfSysPeriod = asOfSysPeriod;
+  }
+
+  public String getAsOfView(String table) {
+    return asOfTableMap.get(table);
+  }
+
+  public String getSysPeriodLower(String tableAlias) {
+
+    return dbHistorySupport.getSysPeriodLower(tableAlias, asOfSysPeriod);
+  }
+
+  public String getSysPeriodUpper(String tableAlias) {
+
+    return dbHistorySupport.getSysPeriodUpper(tableAlias, asOfSysPeriod);
+  }
+
+}

src/main/java/com/avaje/ebeaninternal/server/query/DefaultDbSqlContext.java

@@ -8,7 +8,6 @@ import com.avaje.ebeaninternal.server.util.ArrayStack;
 
 import java.util.ArrayList;
 import java.util.HashSet;
-import java.util.Map;
 
 public class DefaultDbSqlContext implements DbSqlContext {
 
@@ -46,22 +45,22 @@ public class DefaultDbSqlContext implements DbSqlContext {
 
   private ArrayList<BeanProperty> encryptedProps;
 
-  private final Map<String,String> asOfTableMap;
+  private final CQueryHistorySupport historySupport;
 
-  private final boolean asOfQuery;
+  private final boolean historyQuery;
 
   /**
    * Construct for SELECT clause (with column alias settings).
    */
   public DefaultDbSqlContext(SqlTreeAlias alias, String tableAliasPlaceHolder,
-      String columnAliasPrefix, boolean alwaysUseColumnAlias, Map<String,String> asOfTableMap) {
+      String columnAliasPrefix, boolean alwaysUseColumnAlias, CQueryHistorySupport historySupport) {
 
     this.alias = alias;
     this.tableAliasPlaceHolder = tableAliasPlaceHolder;
     this.columnAliasPrefix = columnAliasPrefix;
     this.useColumnAlias = alwaysUseColumnAlias;
-    this.asOfTableMap = asOfTableMap;
-    this.asOfQuery = (asOfTableMap != null);
+    this.historySupport = historySupport;
+    this.historyQuery = (historySupport != null);
   }
 
   public void addEncryptedProp(BeanProperty p) {
@@ -106,13 +105,14 @@ public class DefaultDbSqlContext implements DbSqlContext {
 
     sb.append(" ");
     sb.append(type);
-    if (!asOfQuery) {
+    if (!historyQuery) {
       sb.append(" ").append(table).append(" ");
 
     } else {
       // check if there is an associated history table and if so
       // use the unionAll view - we expect an additional predicate to match
-      String withHistoryTable = asOfTableMap.get(table);
+      String withHistoryTable = historySupport.getAsOfView(table);
+
       if (withHistoryTable != null) {
         // there is an associated history table and view so use that
         sb.append(" ").append(withHistoryTable).append(" ");
@@ -227,6 +227,29 @@ public class DefaultDbSqlContext implements DbSqlContext {
     sb.append(converted);
   }
 
+  @Override
+  public void appendHistorySysPeriod() {
+
+    String tableAlias = tableAliasStack.peek();
+
+    sb.append(COMMA);
+    sb.append(historySupport.getSysPeriodLower(tableAlias));
+    appendColumnAlias();
+
+    sb.append(COMMA);
+    sb.append(historySupport.getSysPeriodUpper(tableAlias));
+    appendColumnAlias();
+  }
+
+  private void appendColumnAlias() {
+    if (useColumnAlias) {
+      sb.append(" ");
+      sb.append(columnAliasPrefix);
+      sb.append(columnIndex);
+    }
+    columnIndex++;
+  }
+
   public void appendColumn(String column) {
     appendColumn(tableAliasStack.peek(), column);
   }
@@ -244,12 +267,7 @@ public class DefaultDbSqlContext implements DbSqlContext {
       sb.append(PERIOD);
       sb.append(column);
     }
-    if (useColumnAlias) {
-      sb.append(" ");
-      sb.append(columnAliasPrefix);
-      sb.append(columnIndex);
-    }
-    columnIndex++;
+    appendColumnAlias();
   }
 
   public String peekTableAlias() {
@@ -260,12 +278,7 @@ public class DefaultDbSqlContext implements DbSqlContext {
     sb.append(COMMA);
     sb.append(rawcolumnWithTableAlias);
 
-    if (useColumnAlias) {
-      sb.append(" ");
-      sb.append(columnAliasPrefix);
-      sb.append(columnIndex);
-    }
-    columnIndex++;
+    appendColumnAlias();
   }
 
   public int length() {

src/main/java/com/avaje/ebeaninternal/server/query/DefaultOrmQueryEngine.java

@@ -1,6 +1,7 @@
 package com.avaje.ebeaninternal.server.query;
 
 import com.avaje.ebean.QueryIterator;
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.BeanCollection;
 import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebean.event.BeanFindController;
@@ -12,6 +13,7 @@ import com.avaje.ebeaninternal.server.core.OrmQueryRequest;
 import com.avaje.ebeaninternal.server.deploy.BeanDescriptor;
 
 import java.util.Collection;
+import java.util.List;
 
 /**
  * Main Finder implementation.
@@ -65,6 +67,13 @@ public class DefaultOrmQueryEngine implements OrmQueryEngine {
     return queryEngine.findIterate(request);
   }
 
+  @Override
+  public <T> List<Version<T>> findVersions(OrmQueryRequest<T> request) {
+
+    flushJdbcBatchOnQuery(request);
+    return queryEngine.findVersions(request);
+  }
+
   public <T> BeanCollection<T> findMany(OrmQueryRequest<T> request) {
 
     flushJdbcBatchOnQuery(request);

src/main/java/com/avaje/ebeaninternal/server/query/SqlTreeBuilder.java

@@ -98,7 +98,7 @@ public class SqlTreeBuilder {
    * to the root node.
    */
   public SqlTreeBuilder(String tableAliasPlaceHolder, String columnAliasPrefix,
-      OrmQueryRequest<?> request, CQueryPredicates predicates, Map<String,String> asOfTables) {
+      OrmQueryRequest<?> request, CQueryPredicates predicates, CQueryHistorySupport historySupport) {
 
     this.rawSql = false;
     this.rawNoId = false;
@@ -112,7 +112,7 @@ public class SqlTreeBuilder {
 
     this.predicates = predicates;
     this.alias = new SqlTreeAlias(request.getQuery().getAlias()==null?request.getBeanDescriptor().getBaseTableAlias():request.getQuery().getAlias());
-    this.ctx = new DefaultDbSqlContext(alias, tableAliasPlaceHolder, columnAliasPrefix, !subQuery, asOfTables);
+    this.ctx = new DefaultDbSqlContext(alias, tableAliasPlaceHolder, columnAliasPrefix, !subQuery, historySupport);
   }
 
   /**

src/main/java/com/avaje/ebeaninternal/server/query/SqlTreeNode.java

@@ -1,5 +1,6 @@
 package com.avaje.ebeaninternal.server.query;
 
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebeaninternal.api.SpiQuery;
 import com.avaje.ebeaninternal.server.deploy.DbReadContext;
@@ -47,4 +48,8 @@ public interface SqlTreeNode {
    */
   EntityBean load(DbReadContext ctx, EntityBean localBean, EntityBean contextBean) throws SQLException;
 
+  /**
+   * Load a version of a @History bean with effective dates.
+   */
+  <T> Version<T> loadVersion(DbReadContext ctx) throws SQLException;
 }

src/main/java/com/avaje/ebeaninternal/server/query/SqlTreeNodeBean.java

@@ -1,10 +1,12 @@
 package com.avaje.ebeaninternal.server.query;
 
 import java.sql.SQLException;
+import java.sql.Timestamp;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.BeanCollection;
 import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebean.bean.EntityBeanIntercept;
@@ -73,6 +75,8 @@ public class SqlTreeNodeBean implements SqlTreeNode {
 
   protected final SpiQuery.TemporalMode temporalMode;
 
+  protected final boolean temporalVersions;
+
   private final IdBinder lazyLoadParentIdBinder;
 
   protected String baseTableAlias;
@@ -101,6 +105,8 @@ public class SqlTreeNodeBean implements SqlTreeNode {
     this.nodeBeanProp = beanProp;
     this.desc = desc;
     this.temporalMode = temporalMode;
+    this.temporalVersions = temporalMode == SpiQuery.TemporalMode.VERSIONS;
+
     this.inheritInfo = desc.getInheritInfo();
     this.extraWhere = (beanProp == null) ? null : beanProp.getExtraWhere();
 
@@ -108,7 +114,7 @@ public class SqlTreeNodeBean implements SqlTreeNode {
 
     // the bean has an Id property and we want to use it
     this.readId = withId && (desc.getIdProperty() != null);
-    this.disableLazyLoad = !readId || desc.isSqlSelectBased();
+    this.disableLazyLoad = !readId || desc.isSqlSelectBased() || temporalVersions;
 
     this.tableJoins = props.getTableJoins();
 
@@ -164,6 +170,20 @@ public class SqlTreeNodeBean implements SqlTreeNode {
     }
   }
 
+  /**
+   * Read the version bean.
+   */
+  public <T> Version<T> loadVersion(DbReadContext ctx) throws SQLException {
+
+    // read the sys period lower and upper bounds
+    // these are always the first 2 columns in the resultSet
+    Timestamp start = ctx.getDataReader().getTimestamp();
+    Timestamp end = ctx.getDataReader().getTimestamp();
+    T bean = (T)load(ctx, null, null);
+
+    return new Version(bean, start, end);
+  }
+
   /**
    * read the properties from the resultSet.
    */
@@ -206,14 +226,14 @@ public class SqlTreeNodeBean implements SqlTreeNode {
 
     Mode queryMode = ctx.getQueryMode();
 
-    PersistenceContext persistenceContext = !readId ? null : ctx.getPersistenceContext();
+    PersistenceContext persistenceContext = (!readId || temporalVersions) ? null : ctx.getPersistenceContext();
 
     if (readId) {
       Object id = localIdBinder.readSet(ctx, localBean);
       if (id == null) {
         // bean must be null...
         localBean = null;
-      } else {
+      } else if (!temporalVersions) {
         // check the PersistenceContext to see if the bean already exists
         contextBean = (EntityBean)persistenceContext.putIfAbsent(id, localBean);
         if (contextBean == null) {
@@ -278,7 +298,7 @@ public class SqlTreeNodeBean implements SqlTreeNode {
 
     if (!lazyLoadMany && localBean != null) {
       ctx.setCurrentPrefix(prefix, pathMap);
-      if (readId) {
+      if (readId && !temporalVersions) {
         createListProxies(localDesc, ctx, localBean);
       }
       localDesc.postLoad(localBean, null);
@@ -293,7 +313,11 @@ public class SqlTreeNodeBean implements SqlTreeNode {
         ebi.setLoaded();
       }
 
-      if (partialObject) {
+      if (disableLazyLoad) {
+        // bean does not have an Id or is SqlSelect based
+        ebi.setDisableLazyLoad(true);
+
+      } else if (partialObject) {
         if (readId) {
           // register for lazy loading
           ctx.register(null, ebi);
@@ -302,11 +326,7 @@ public class SqlTreeNodeBean implements SqlTreeNode {
         ebi.setFullyLoadedBean(true);
       }
 
-      if (disableLazyLoad) {
-        // bean does not have an Id or is SqlSelect based
-        ebi.setDisableLazyLoad(true);
-      }
-      if (ctx.isAutoFetchProfiling()) {
+      if (ctx.isAutoFetchProfiling() && !disableLazyLoad) {
         // collect autofetch profiling for this bean...
         ctx.profileBean(ebi, prefix);
       }
@@ -317,7 +337,7 @@ public class SqlTreeNodeBean implements SqlTreeNode {
       nodeBeanProp.setValue(parentBean, contextBean);
     }
 
-    if (!readId) {
+    if (!readId || temporalVersions) {
       // a bean with no Id (never found in context)
       return localBean;
 
@@ -358,7 +378,12 @@ public class SqlTreeNodeBean implements SqlTreeNode {
 
     ctx.pushJoin(prefix);
     ctx.pushTableAlias(prefix);
-    
+
+    if (temporalVersions) {
+      // select sys_period lower and upper columns
+      ctx.appendHistorySysPeriod();
+    }
+
     if (lazyLoadParent != null) {
       lazyLoadParent.addSelectExported(ctx, prefix);
     }

src/main/java/com/avaje/ebeaninternal/server/query/SqlTreeNodeExtraJoin.java

@@ -1,5 +1,6 @@
 package com.avaje.ebeaninternal.server.query;
 
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebeaninternal.api.SpiQuery;
 import com.avaje.ebeaninternal.server.deploy.BeanPropertyAssoc;
@@ -126,4 +127,11 @@ public class SqlTreeNodeExtraJoin implements SqlTreeNode {
     return null;
   }
 
+  /**
+   * Does nothing.
+   */
+  @Override
+  public <T> Version<T> loadVersion(DbReadContext ctx) throws SQLException {
+    return null;
+  }
 }

src/main/java/com/avaje/ebeaninternal/server/query/SqlTreeNodeManyWhereJoin.java

@@ -1,5 +1,6 @@
 package com.avaje.ebeaninternal.server.query;
 
+import com.avaje.ebean.Version;
 import com.avaje.ebean.bean.EntityBean;
 import com.avaje.ebeaninternal.api.SpiQuery;
 import com.avaje.ebeaninternal.server.deploy.BeanPropertyAssoc;
@@ -98,4 +99,9 @@ public class SqlTreeNodeManyWhereJoin implements SqlTreeNode {
     return null;
   }
 
+  @Override
+  public <T> Version<T> loadVersion(DbReadContext ctx) throws SQLException {
+    // nothing to do here
+    return null;
+  }
 }

src/main/java/com/avaje/ebeaninternal/server/querydefn/DefaultOrmQuery.java

@@ -163,6 +163,8 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
    */
   private Timestamp asOf;
 
+  private TemporalMode temporalMode = TemporalMode.CURRENT;
+
   private int bufferFetchSizeHint;
 
   private boolean usageProfiling = true;
@@ -288,6 +290,7 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
   }
 
   public DefaultOrmQuery<T> asOf(Timestamp asOfDateTime) {
+    this.temporalMode = (asOfDateTime != null) ? TemporalMode.AS_OF : TemporalMode.CURRENT;
     this.asOf = asOfDateTime;
     return this;
   }
@@ -617,7 +620,7 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
 
   @Override
   public TemporalMode getTemporalMode() {
-    return asOf == null ? TemporalMode.CURRENT : TemporalMode.AS_OF;
+    return temporalMode;
   }
 
   public boolean isAsOfQuery() {
@@ -952,6 +955,12 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
     server.findEach(this, consumer, null);
   }
 
+  @Override
+  public List<Version<T>> findVersions() {
+    this.temporalMode = TemporalMode.VERSIONS;
+    return server.findVersions(this, null);
+  }
+
   public QueryIterator<T> findIterate() {
     return server.findIterate(this, null);
   }

src/main/java/com/avaje/ebeaninternal/util/DefaultExpressionList.java

@@ -113,6 +113,11 @@ public class DefaultExpressionList<T> implements SpiExpressionList<T> {
     return query.asOf(asOf);
   }
 
+  @Override
+  public List<Version<T>> findVersions() {
+    return query.findVersions();
+  }
+
   @Override
   public ExpressionList<T> where() {
     return query.where();