#752 - Refactor: SQL generation for @History support with Postgres, MySql (views/triggers based) such that it more closely aligns with SQL 2011 based SQL

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

@@ -6,11 +6,13 @@ package com.avaje.ebean.config.dbplatform;
 public interface DbHistorySupport {
 
   /**
-   * Return true if the 'As of' predicate is part of the from clause
-   * (more standard sql2011). So true for Oracle total recall and false
-   * for Postgres and MySql (where we use views and history tables).
+   * Return true if the implementation is SQL2011 standards based.
+   * <p>
+   * Non standards based means we need to add additional predicates into the
+   * JOIN ON clause and add an additional predicate for the base table.
+   * </p>
    */
-  boolean isBindWithFromClause();
+  boolean isStandardsBased();
 
   /**
    * Return the number of columns bound in a 'As Of' predicate.

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

@@ -5,11 +5,8 @@ package com.avaje.ebean.config.dbplatform;
  */
 public abstract class DbStandardHistorySupport implements DbHistorySupport {
 
-  /**
-   * Return true as with sql2011 the 'as of timestamp' clause included in from or join clause.
-   */
   @Override
-  public boolean isBindWithFromClause() {
+  public boolean isStandardsBased() {
     return true;
   }
 

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

@@ -9,11 +9,8 @@ package com.avaje.ebean.config.dbplatform;
  */
 public abstract class DbViewHistorySupport implements DbHistorySupport {
 
-  /**
-   * Return false for view based implementations where we append extra 'as of' predicates to the end.
-   */
   @Override
-  public boolean isBindWithFromClause() {
+  public boolean isStandardsBased() {
     return false;
   }
 

src/main/java/com/avaje/ebeaninternal/api/SpiQuery.java

@@ -223,14 +223,14 @@ public interface SpiQuery<T> extends Query<T> {
   Timestamp getAsOf();
 
   /**
-   * Add a table alias for a @History entity involved in a 'As Of' query.
+   * Increment the counter of tables used in 'As Of' query.
    */
-  void addAsOfTableAlias(String tableAlias);
+  void incrementAsOfTableCount();
 
   /**
-   * Return the list of table alias involved in a 'As Of' query that have @History support.
+   * Return the table alias used for the base table.
    */
-  List<String> getAsOfTableAlias();
+  int getAsOfTableCount();
 
   void addSoftDeletePredicate(String softDeletePredicate);
 

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

@@ -235,7 +235,7 @@ public class InternalConfiguration {
     if (historySupport == null) {
       return new Binder(typeManager, 0, false, jsonHandler, dataTimeZone);
     }
-    return new Binder(typeManager, historySupport.getBindCount(), historySupport.isBindWithFromClause(), jsonHandler, dataTimeZone);
+    return new Binder(typeManager, historySupport.getBindCount(), historySupport.isStandardsBased(), jsonHandler, dataTimeZone);
   }
 
   /**

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

@@ -513,4 +513,11 @@ public final class OrmQueryRequest<T> extends BeanRequest implements BeanQueryRe
   public boolean isAuditReads() {
     return !query.isDisableReadAudit() && beanDescriptor.isReadAuditing();
   }
+
+  /**
+   * Return the base table alias for this query.
+   */
+  public String getBaseTableAlias() {
+    return query.getAlias() == null ? beanDescriptor.getBaseTableAlias() : query.getAlias();
+  }
 }

src/main/java/com/avaje/ebeaninternal/server/persist/Binder.java

@@ -33,7 +33,7 @@ public class Binder {
 
   private final int asOfBindCount;
 
-  private final boolean bindAsOfWithFromClause;
+  private final boolean asOfStandardsBased;
 
   private final DbExpressionHandler dbExpressionHandler;
 
@@ -42,12 +42,12 @@ public class Binder {
   /**
    * Set the PreparedStatement with which to bind variables to.
    */
-  public Binder(TypeManager typeManager, int asOfBindCount, boolean bindAsOfWithFromClause,
+  public Binder(TypeManager typeManager, int asOfBindCount, boolean asOfStandardsBased,
                 DbExpressionHandler dbExpressionHandler, DataTimeZone dataTimeZone) {
 
     this.typeManager = typeManager;
     this.asOfBindCount = asOfBindCount;
-    this.bindAsOfWithFromClause = bindAsOfWithFromClause;
+    this.asOfStandardsBased = asOfStandardsBased;
     this.dbExpressionHandler = dbExpressionHandler;
     this.dataTimeZone = dataTimeZone;
   }
@@ -60,12 +60,10 @@ public class Binder {
   }
 
   /**
-   * Return true if the 'as of' predicates are in the from/join clause in which case the timestamp is
-   * bound early (before all the other predicates ala Oracle). Return false if the 'as of' predicates are
-   * appended to the end of the predicates and the timestamp is bound last (Postgres, MySql).
+   * Return true if the 'as of' history support is SQL2011 standards based.
    */
-  public boolean isBindAsOfWithFromClause() {
-    return bindAsOfWithFromClause;
+  public boolean isAsOfStandardsBased() {
+    return asOfStandardsBased;
   }
 
   /**

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

@@ -472,12 +472,14 @@ public class CQueryBuilder {
       hasWhere = true;
     }
 
+    int asOfCount = query.getAsOfTableCount();
+    if (asOfCount > 0 && !historySupport.isStandardsBased()) {
+      hasWhere = appendWhere(hasWhere, sb);
+      sb.append(historySupport.getAsOfPredicate(request.getBaseTableAlias()));
+    }
+
     if (request.isFindById() || query.getId() != null) {
-      if (hasWhere) {
-        sb.append(" and ");
-      } else {
-        sb.append(" where ");
-      }
+      appendWhere(hasWhere, sb);
 
       BeanDescriptor<?> desc = request.getBeanDescriptor();
       String idSql = desc.getIdBinderIdSql();
@@ -515,24 +517,6 @@ public class CQueryBuilder {
       sb.append(dbFilterMany);
     }
 
-    List<String> asOfTableAlias = query.getAsOfTableAlias();
-    if (asOfTableAlias != null && !historySupport.isBindAtFromClause()) {
-      // append the effective date predicates for each table alias
-      // that maps to a @History entity involved in this query
-      // Do this when history using separate tables/views (PG, MySql etc)
-      if (!hasWhere) {
-        sb.append(" where ");
-      } else {
-        sb.append("and ");
-      }
-      for (int i = 0; i < asOfTableAlias.size(); i++) {
-        if (i > 0) {
-          sb.append(" and ");
-        }
-        sb.append(historySupport.getAsOfPredicate(asOfTableAlias.get(i)));
-      }
-    }
-
     if (!query.isIncludeSoftDeletes()) {
       List<String> softDeletePredicates = query.getSoftDeletePredicates();
       if (softDeletePredicates != null) {
@@ -565,6 +549,18 @@ public class CQueryBuilder {
 
   }
 
+  /**
+   * Append where or and based on the hasWhere flag.
+   */
+  private boolean appendWhere(boolean hasWhere, StringBuilder sb) {
+    if (hasWhere) {
+      sb.append(" and ");
+    } else {
+      sb.append(" where ");
+    }
+    return true;
+  }
+
   /**
    * Convert the dbOrderBy clause to be safe for adding to select. This is done when 'distinct' is
    * used.

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

@@ -206,7 +206,7 @@ public class CQueryEngine {
     SpiQuery<T> query = request.getQuery();
 
     String sysPeriodLower = getSysPeriodLower(query);
-    if (query.isVersionsBetween() && !historySupport.isBindAtFromClause()) {
+    if (query.isVersionsBetween() && !historySupport.isStandardsBased()) {
       // just add as normal predicates using the lower bound
       query.where().gt(sysPeriodLower, query.getVersionStart());
       query.where().lt(sysPeriodLower, query.getVersionEnd());

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

@@ -31,11 +31,10 @@ public class CQueryHistorySupport {
   }
 
   /**
-   * Return true if the bind of 'as of' timestamp occurs with the from clause
-   * rather than at the end.
+   * Return true if the underlying history support is standards based.
    */
-  public boolean isBindAtFromClause() {
-    return dbHistorySupport.isBindWithFromClause();
+  public boolean isStandardsBased() {
+    return dbHistorySupport.isStandardsBased();
   }
 
   /**

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

@@ -126,7 +126,7 @@ public class CQueryPredicates {
       updateProperties.bind(binder, dataBind);
     }
 
-    if (query.isVersionsBetween() && binder.isBindAsOfWithFromClause()) {
+    if (query.isVersionsBetween() && binder.isAsOfStandardsBased()) {
       // sql2011 based versions between timestamp syntax
       Timestamp start = query.getVersionStart();
       Timestamp end = query.getVersionEnd();
@@ -136,13 +136,13 @@ public class CQueryPredicates {
       dataBind.append(", ");
     }
 
-    List<String> historyTableAlias = query.getAsOfTableAlias();
-    if (historyTableAlias != null && binder.isBindAsOfWithFromClause()) {
+    int asOfTableCount = query.getAsOfTableCount();
+    if (asOfTableCount > 0) {
       // bind the asOf value for each table alias as part of the from/join clauses
       // there is one effective date predicate per table alias
       Timestamp asOf = query.getAsOf();
       dataBind.append("asOf ").append(asOf);
-      for (int i = 0; i < historyTableAlias.size() * binder.getAsOfBindCount(); i++) {
+      for (int i = 0; i < asOfTableCount * binder.getAsOfBindCount(); i++) {
         binder.bindObject(dataBind, asOf);
       }
       dataBind.append(", ");
@@ -167,16 +167,6 @@ public class CQueryPredicates {
       filterMany.bind(dataBind);
     }
 
-    if (historyTableAlias != null && !binder.isBindAsOfWithFromClause()) {
-      // bind the asOf value for each table alias after all the normal predicates
-      // there is one effective date predicate per table alias
-      Timestamp asOf = query.getAsOf();
-      dataBind.append(" asOf ").append(asOf);
-      for (int i = 0; i < historyTableAlias.size() * binder.getAsOfBindCount(); i++) {
-        binder.bindObject(dataBind, asOf);
-      }
-    }
-
     if (having != null) {
       having.bind(dataBind);
     }

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

@@ -106,8 +106,8 @@ public class DefaultDbSqlContext implements DbSqlContext {
 
     tableJoins.add(joinKey);
 
-    sb.append(" ");
-    sb.append(type);
+    sb.append(" ").append(type);
+    boolean addAsOfOnClause = false;
     if (draftSupport != null) {
       appendTable(table, draftSupport.getDraftTable(table));
 
@@ -117,32 +117,32 @@ public class DefaultDbSqlContext implements DbSqlContext {
     } else {
       // check if there is an associated history table and if so
       // use the unionAll view - we expect an additional predicate to match
-      appendTable(table, historySupport.getAsOfView(table));
+      String asOfView = historySupport.getAsOfView(table);
+      appendTable(table, asOfView);
+      if (asOfView != null) {
+        addAsOfOnClause = !historySupport.isStandardsBased();
+      }
     }
 
     sb.append(a2);
     sb.append(" on ");
-
     for (int i = 0; i < cols.length; i++) {
       TableJoinColumn pair = cols[i];
       if (i > 0) {
         sb.append(" and ");
       }
-
-      sb.append(a2);
-      sb.append(".").append(pair.getForeignDbColumn());
+      sb.append(a2).append(".").append(pair.getForeignDbColumn());
       sb.append(" = ");
-      sb.append(a1);
-      sb.append(".").append(pair.getLocalDbColumn());
+      sb.append(a1).append(".").append(pair.getLocalDbColumn());
     }
 
-
     // add on any inheritance where clause
     if (inheritance != null && inheritance.length() > 0) {
-      sb.append(" and ");
-      sb.append(a2);
-      sb.append(".");
-      sb.append(inheritance);
+      sb.append(" and ").append(a2).append(".").append(inheritance);
+    }
+
+    if (addAsOfOnClause) {
+      sb.append(" and ").append(historySupport.getAsOfPredicate(a2));
     }
 
     sb.append(" ");

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

@@ -111,7 +111,7 @@ public class SqlTreeBuilder {
     this.queryDetail = query.getDetail();
 
     this.predicates = predicates;
-    this.alias = new SqlTreeAlias(request.getQuery().getAlias() == null ? request.getBeanDescriptor().getBaseTableAlias() : request.getQuery().getAlias());
+    this.alias = new SqlTreeAlias(request.getBaseTableAlias());
     this.ctx = new DefaultDbSqlContext(alias, tableAliasPlaceHolder, columnAliasPrefix, !subQuery, historySupport, draftSupport);
   }
 

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

@@ -81,7 +81,7 @@ public class SqlTreeNodeBean implements SqlTreeNode {
    * Table alias set if this bean node includes a join to a intersection
    * table and that table has history support.
    */
-  protected String intersectionAsOfTableAlias;
+  private boolean intersectionAsOfTableAlias;
 
   /**
    * Construct for Raw SQL.
@@ -501,11 +501,10 @@ public class SqlTreeNodeBean implements SqlTreeNode {
     // if history on this bean type add it's alias
     // for each alias we add an effect date predicate
     if (desc.isHistorySupport()) {
-      query.addAsOfTableAlias(baseTableAlias);
+      query.incrementAsOfTableCount();
     }
-    if (intersectionAsOfTableAlias != null) {
-      // adds the 'as of' predicate for this intersection table
-      query.addAsOfTableAlias(intersectionAsOfTableAlias);
+    if (intersectionAsOfTableAlias) {
+      query.incrementAsOfTableCount();
     }
     for (int i = 0; i < children.length; i++) {
       children[i].addAsOfTableAlias(query);
@@ -531,7 +530,7 @@ public class SqlTreeNodeBean implements SqlTreeNode {
         TableJoin manyToManyJoin = manyProp.getIntersectionTableJoin();
         manyToManyJoin.addJoin(joinType, parentAlias, alias2, ctx);
         if (!manyProp.isExcludedFromHistory()) {
-          intersectionAsOfTableAlias = alias2;
+          intersectionAsOfTableAlias = true;
         }
 
         return nodeBeanProp.addJoin(joinType, alias2, alias, ctx);

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

@@ -144,10 +144,7 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
 
   private DefaultExpressionList<T> havingExpressions;
 
-  /**
-   * The list of table alias associated with @History entity beans.
-   */
-  private List<String> asOfTableAlias;
+  private int asOfTableCount;
 
   /**
    * Set for flashback style 'as of' query.
@@ -281,21 +278,14 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
     return softDeletePredicates;
   }
 
-  /**
-   * This table alias is for a @History entity involved in the query and as
-   * such we need to add a 'as of predicate' to the query using this alias.
-   */
   @Override
-  public void addAsOfTableAlias(String tableAlias) {
-    if (asOfTableAlias == null) {
-      asOfTableAlias = new ArrayList<String>();
-    }
-    asOfTableAlias.add(tableAlias);
+  public void incrementAsOfTableCount() {
+    asOfTableCount++;
   }
 
   @Override
-  public List<String> getAsOfTableAlias() {
-    return asOfTableAlias;
+  public int getAsOfTableCount() {
+    return asOfTableCount;
   }
 
   @Override