Examples with StatementClassMapping org.datanucleus.store.rdbms.query.StatementClassMapping used on opensource projects

Example 6 with StatementClassMapping

use of org.datanucleus.store.rdbms.query.StatementClassMapping in project datanucleus-rdbms by datanucleus.

the class FKArrayStore method getIteratorStatement.

/**
 * Method to return the SQLStatement and mapping for an iterator for this backing store.
 * Create a statement of the form
 * <pre>
 * SELECT ELEM_COLS
 * FROM ELEM_TBL
 * [WHERE]
 *   [ELEM_TBL.OWNER_ID = {value}] [AND]
 *   [ELEM_TBL.DISCRIM = {discrimValue}]
 * [ORDER BY {orderClause}]
 * </pre>
 * @param ec ExecutionContext
 * @param fp FetchPlan to use in determing which fields of element to select
 * @param addRestrictionOnOwner Whether to restrict to a particular owner (otherwise functions as bulk fetch for many owners).
 * @return The SQLStatement and its associated StatementClassMapping
 */
public IteratorStatement getIteratorStatement(ExecutionContext ec, FetchPlan fp, boolean addRestrictionOnOwner) {
    SelectStatement sqlStmt = null;
    SQLExpressionFactory exprFactory = storeMgr.getSQLExpressionFactory();
    StatementClassMapping iteratorMappingClass = new StatementClassMapping();
    if (elementInfo[0].getDatastoreClass().getDiscriminatorMetaData() != null && elementInfo[0].getDatastoreClass().getDiscriminatorMetaData().getStrategy() != DiscriminatorStrategy.NONE) {
        String elementType = ownerMemberMetaData.getArray().getElementType();
        if (ClassUtils.isReferenceType(clr.classForName(elementType))) {
            String[] clsNames = storeMgr.getNucleusContext().getMetaDataManager().getClassesImplementingInterface(elementType, clr);
            Class[] cls = new Class[clsNames.length];
            for (int i = 0; i < clsNames.length; i++) {
                cls[i] = clr.classForName(clsNames[i]);
            }
            sqlStmt = new DiscriminatorStatementGenerator(storeMgr, clr, cls, true, null, null).getStatement(ec);
        } else {
            sqlStmt = new DiscriminatorStatementGenerator(storeMgr, clr, clr.classForName(elementInfo[0].getClassName()), true, null, null).getStatement(ec);
        }
        iterateUsingDiscriminator = true;
        // Select the required fields
        SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(sqlStmt, iteratorMappingClass, fp, sqlStmt.getPrimaryTable(), elementCmd, fp.getMaxFetchDepth());
    } else {
        for (int i = 0; i < elementInfo.length; i++) {
            final Class elementCls = clr.classForName(this.elementInfo[i].getClassName());
            UnionStatementGenerator stmtGen = new UnionStatementGenerator(storeMgr, clr, elementCls, true, null, null);
            stmtGen.setOption(SelectStatementGenerator.OPTION_SELECT_DN_TYPE);
            iteratorMappingClass.setNucleusTypeColumnName(UnionStatementGenerator.DN_TYPE_COLUMN);
            SelectStatement subStmt = stmtGen.getStatement(ec);
            // Select the required fields (of the element class)
            if (sqlStmt == null) {
                if (elementInfo.length > 1) {
                    SQLStatementHelper.selectIdentityOfCandidateInStatement(subStmt, iteratorMappingClass, elementInfo[i].getAbstractClassMetaData());
                } else {
                    SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(subStmt, iteratorMappingClass, fp, subStmt.getPrimaryTable(), elementInfo[i].getAbstractClassMetaData(), fp.getMaxFetchDepth());
                }
            } else {
                if (elementInfo.length > 1) {
                    SQLStatementHelper.selectIdentityOfCandidateInStatement(subStmt, null, elementInfo[i].getAbstractClassMetaData());
                } else {
                    SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(subStmt, null, fp, subStmt.getPrimaryTable(), elementInfo[i].getAbstractClassMetaData(), fp.getMaxFetchDepth());
                }
            }
            if (sqlStmt == null) {
                sqlStmt = subStmt;
            } else {
                sqlStmt.union(subStmt);
            }
        }
    }
    if (sqlStmt == null) {
        throw new NucleusException("Error in generation of SQL statement for iterator over (FK) array. Statement is null");
    }
    if (addRestrictionOnOwner) {
        // Apply condition to filter by owner
        SQLTable ownerSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), ownerMapping);
        SQLExpression ownerExpr = exprFactory.newExpression(sqlStmt, ownerSqlTbl, ownerMapping);
        SQLExpression ownerVal = exprFactory.newLiteralParameter(sqlStmt, ownerMapping, null, "OWNER");
        sqlStmt.whereAnd(ownerExpr.eq(ownerVal), true);
    }
    if (relationDiscriminatorMapping != null) {
        // Apply condition on distinguisher field to filter by distinguisher (when present)
        SQLTable distSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), relationDiscriminatorMapping);
        SQLExpression distExpr = exprFactory.newExpression(sqlStmt, distSqlTbl, relationDiscriminatorMapping);
        SQLExpression distVal = exprFactory.newLiteral(sqlStmt, relationDiscriminatorMapping, relationDiscriminatorValue);
        sqlStmt.whereAnd(distExpr.eq(distVal), true);
    }
    if (orderMapping != null) {
        // Order by the ordering column, when present
        SQLTable orderSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
        SQLExpression[] orderExprs = new SQLExpression[orderMapping.getNumberOfDatastoreMappings()];
        boolean[] descendingOrder = new boolean[orderMapping.getNumberOfDatastoreMappings()];
        orderExprs[0] = exprFactory.newExpression(sqlStmt, orderSqlTbl, orderMapping);
        sqlStmt.setOrdering(orderExprs, descendingOrder);
    }
    return new IteratorStatement(this, sqlStmt, iteratorMappingClass);
}

Example 7 with StatementClassMapping

use of org.datanucleus.store.rdbms.query.StatementClassMapping in project datanucleus-rdbms by datanucleus.

the class FKArrayStore method iterator.

/**
 * Accessor for an iterator for the set.
 * @param ownerOP ObjectProvider for the set.
 * @return Iterator for the set.
 */
public Iterator<E> iterator(ObjectProvider ownerOP) {
    ExecutionContext ec = ownerOP.getExecutionContext();
    if (elementInfo == null || elementInfo.length == 0) {
        return null;
    }
    // Generate the statement, and statement mapping/parameter information
    IteratorStatement iterStmt = getIteratorStatement(ownerOP.getExecutionContext(), ownerOP.getExecutionContext().getFetchPlan(), true);
    SelectStatement sqlStmt = iterStmt.getSelectStatement();
    StatementClassMapping iteratorMappingDef = iterStmt.getStatementClassMapping();
    // Input parameter(s) - the owner
    int inputParamNum = 1;
    StatementMappingIndex ownerIdx = new StatementMappingIndex(ownerMapping);
    if (sqlStmt.getNumberOfUnions() > 0) {
        // Add parameter occurrence for each union of statement
        for (int j = 0; j < sqlStmt.getNumberOfUnions() + 1; j++) {
            int[] paramPositions = new int[ownerMapping.getNumberOfDatastoreMappings()];
            for (int k = 0; k < ownerMapping.getNumberOfDatastoreMappings(); k++) {
                paramPositions[k] = inputParamNum++;
            }
            ownerIdx.addParameterOccurrence(paramPositions);
        }
    } else {
        int[] paramPositions = new int[ownerMapping.getNumberOfDatastoreMappings()];
        for (int k = 0; k < ownerMapping.getNumberOfDatastoreMappings(); k++) {
            paramPositions[k] = inputParamNum++;
        }
        ownerIdx.addParameterOccurrence(paramPositions);
    }
    StatementParameterMapping iteratorMappingParams = new StatementParameterMapping();
    iteratorMappingParams.addMappingForParameter("owner", ownerIdx);
    if (ec.getTransaction().getSerializeRead() != null && ec.getTransaction().getSerializeRead()) {
        sqlStmt.addExtension(SQLStatement.EXTENSION_LOCK_FOR_UPDATE, true);
    }
    String stmt = sqlStmt.getSQLText().toSQL();
    try {
        ManagedConnection mconn = storeMgr.getConnectionManager().getConnection(ec);
        SQLController sqlControl = storeMgr.getSQLController();
        try {
            // Create the statement
            PreparedStatement ps = sqlControl.getStatementForQuery(mconn, stmt);
            // Set the owner
            ObjectProvider stmtOwnerOP = BackingStoreHelper.getOwnerObjectProviderForBackingStore(ownerOP);
            int numParams = ownerIdx.getNumberOfParameterOccurrences();
            for (int paramInstance = 0; paramInstance < numParams; paramInstance++) {
                ownerIdx.getMapping().setObject(ec, ps, ownerIdx.getParameterPositionsForOccurrence(paramInstance), stmtOwnerOP.getObject());
            }
            try {
                ResultSet rs = sqlControl.executeStatementQuery(ec, mconn, stmt, ps);
                try {
                    ResultObjectFactory rof = null;
                    if (elementsAreEmbedded || elementsAreSerialised) {
                        throw new NucleusException("Cannot have FK array with non-persistent objects");
                    }
                    rof = new PersistentClassROF(ec, rs, false, iteratorMappingDef, elementCmd, clr.classForName(elementType));
                    return new ArrayStoreIterator(ownerOP, rs, rof, this);
                } finally {
                    rs.close();
                }
            } finally {
                sqlControl.closeStatement(mconn, ps);
            }
        } finally {
            mconn.release();
        }
    } catch (SQLException | MappedDatastoreException e) {
        throw new NucleusDataStoreException(Localiser.msg("056006", stmt), e);
    }
}

Example 8 with StatementClassMapping

use of org.datanucleus.store.rdbms.query.StatementClassMapping in project datanucleus-rdbms by datanucleus.

the class FKListStore method getIteratorStatement.

/**
 * Method to return the SQLStatement and mapping for an iterator for this backing store.
 * Create a statement of the form
 * <pre>
 * SELECT ELEM_COLS
 * FROM ELEM_TBL
 * [WHERE]
 *   [ELEM_TBL.OWNER_ID = {value}] [AND]
 *   [ELEM_TBL.DISCRIM = {discrimValue}]
 * [ORDER BY {orderClause}]
 * </pre>
 * @param ec ExecutionContext
 * @param fp FetchPlan to use in determing which fields of element to select
 * @param addRestrictionOnOwner Whether to restrict to a particular owner (otherwise functions as bulk fetch for many owners).
 * @param startIdx Start index for the iterator (or -1)
 * @param endIdx End index for the iterator (or -1)
 * @return The SQLStatement and its associated StatementClassMapping
 */
public IteratorStatement getIteratorStatement(ExecutionContext ec, FetchPlan fp, boolean addRestrictionOnOwner, int startIdx, int endIdx) {
    SelectStatement sqlStmt = null;
    StatementClassMapping stmtClassMapping = new StatementClassMapping();
    SQLExpressionFactory exprFactory = storeMgr.getSQLExpressionFactory();
    if (elementInfo.length == 1 && elementInfo[0].getDatastoreClass().getDiscriminatorMetaData() != null && elementInfo[0].getDatastoreClass().getDiscriminatorMetaData().getStrategy() != DiscriminatorStrategy.NONE) {
        String elementType = ownerMemberMetaData.getCollection().getElementType();
        if (ClassUtils.isReferenceType(clr.classForName(elementType))) {
            String[] clsNames = storeMgr.getNucleusContext().getMetaDataManager().getClassesImplementingInterface(elementType, clr);
            Class[] cls = new Class[clsNames.length];
            for (int i = 0; i < clsNames.length; i++) {
                cls[i] = clr.classForName(clsNames[i]);
            }
            sqlStmt = new DiscriminatorStatementGenerator(storeMgr, clr, cls, true, null, null).getStatement(ec);
        } else {
            sqlStmt = new DiscriminatorStatementGenerator(storeMgr, clr, clr.classForName(elementInfo[0].getClassName()), true, null, null).getStatement(ec);
        }
        iterateUsingDiscriminator = true;
        // Select the required fields
        SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(sqlStmt, stmtClassMapping, fp, sqlStmt.getPrimaryTable(), elementCmd, fp.getMaxFetchDepth());
    } else {
        for (int i = 0; i < elementInfo.length; i++) {
            final Class elementCls = clr.classForName(this.elementInfo[i].getClassName());
            UnionStatementGenerator stmtGen = new UnionStatementGenerator(storeMgr, clr, elementCls, true, null, null);
            stmtGen.setOption(SelectStatementGenerator.OPTION_SELECT_DN_TYPE);
            stmtClassMapping.setNucleusTypeColumnName(UnionStatementGenerator.DN_TYPE_COLUMN);
            SelectStatement subStmt = stmtGen.getStatement(ec);
            // Select the required fields (of the element class)
            if (sqlStmt == null) {
                if (elementInfo.length > 1) {
                    SQLStatementHelper.selectIdentityOfCandidateInStatement(subStmt, stmtClassMapping, elementInfo[i].getAbstractClassMetaData());
                } else {
                    SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(subStmt, stmtClassMapping, fp, subStmt.getPrimaryTable(), elementInfo[i].getAbstractClassMetaData(), fp.getMaxFetchDepth());
                }
            } else {
                if (elementInfo.length > 1) {
                    SQLStatementHelper.selectIdentityOfCandidateInStatement(subStmt, null, elementInfo[i].getAbstractClassMetaData());
                } else {
                    SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(subStmt, null, fp, subStmt.getPrimaryTable(), elementInfo[i].getAbstractClassMetaData(), fp.getMaxFetchDepth());
                }
            }
            if (sqlStmt == null) {
                sqlStmt = subStmt;
            } else {
                sqlStmt.union(subStmt);
            }
        }
        if (sqlStmt == null) {
            throw new NucleusException("Unable to generate iterator statement for field=" + getOwnerMemberMetaData().getFullFieldName());
        }
    }
    if (addRestrictionOnOwner) {
        // Apply condition to filter by owner
        // TODO If ownerMapping is not for containerTable then do JOIN to ownerTable in the FROM clause (or find if already done)
        SQLTable ownerSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), ownerMapping);
        SQLExpression ownerExpr = exprFactory.newExpression(sqlStmt, ownerSqlTbl, ownerMapping);
        SQLExpression ownerVal = exprFactory.newLiteralParameter(sqlStmt, ownerMapping, null, "OWNER");
        sqlStmt.whereAnd(ownerExpr.eq(ownerVal), true);
    }
    if (relationDiscriminatorMapping != null) {
        // Apply condition on distinguisher field to filter by distinguisher (when present)
        SQLTable distSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), relationDiscriminatorMapping);
        SQLExpression distExpr = exprFactory.newExpression(sqlStmt, distSqlTbl, relationDiscriminatorMapping);
        SQLExpression distVal = exprFactory.newLiteral(sqlStmt, relationDiscriminatorMapping, relationDiscriminatorValue);
        sqlStmt.whereAnd(distExpr.eq(distVal), true);
    }
    if (indexedList) {
        // "Indexed List" so allow restriction on returned indexes
        boolean needsOrdering = true;
        if (startIdx == -1 && endIdx == -1) {
            // Just restrict to >= 0 so we don't get any disassociated elements
            SQLExpression indexExpr = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
            SQLExpression indexVal = exprFactory.newLiteral(sqlStmt, orderMapping, 0);
            sqlStmt.whereAnd(indexExpr.ge(indexVal), true);
        } else if (startIdx >= 0 && endIdx == startIdx) {
            // Particular index required so add restriction
            needsOrdering = false;
            SQLExpression indexExpr = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
            SQLExpression indexVal = exprFactory.newLiteral(sqlStmt, orderMapping, startIdx);
            sqlStmt.whereAnd(indexExpr.eq(indexVal), true);
        } else {
            // Add restrictions on start/end indices as required
            if (startIdx >= 0) {
                SQLExpression indexExpr = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
                SQLExpression indexVal = exprFactory.newLiteral(sqlStmt, orderMapping, startIdx);
                sqlStmt.whereAnd(indexExpr.ge(indexVal), true);
            } else {
                // Just restrict to >= 0 so we don't get any disassociated elements
                SQLExpression indexExpr = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
                SQLExpression indexVal = exprFactory.newLiteral(sqlStmt, orderMapping, 0);
                sqlStmt.whereAnd(indexExpr.ge(indexVal), true);
            }
            if (endIdx >= 0) {
                SQLExpression indexExpr2 = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
                SQLExpression indexVal2 = exprFactory.newLiteral(sqlStmt, orderMapping, endIdx);
                sqlStmt.whereAnd(indexExpr2.lt(indexVal2), true);
            }
        }
        if (needsOrdering) {
            // Order by the ordering column
            SQLTable orderSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), orderMapping);
            SQLExpression[] orderExprs = new SQLExpression[orderMapping.getNumberOfDatastoreMappings()];
            boolean[] descendingOrder = new boolean[orderMapping.getNumberOfDatastoreMappings()];
            orderExprs[0] = exprFactory.newExpression(sqlStmt, orderSqlTbl, orderMapping);
            sqlStmt.setOrdering(orderExprs, descendingOrder);
        }
    } else {
        // Apply ordering defined by <order-by>
        DatastoreClass elementTbl = elementInfo[0].getDatastoreClass();
        FieldOrder[] orderComponents = ownerMemberMetaData.getOrderMetaData().getFieldOrders();
        SQLExpression[] orderExprs = new SQLExpression[orderComponents.length];
        boolean[] orderDirs = new boolean[orderComponents.length];
        for (int i = 0; i < orderComponents.length; i++) {
            String fieldName = orderComponents[i].getFieldName();
            JavaTypeMapping fieldMapping = elementTbl.getMemberMapping(elementInfo[0].getAbstractClassMetaData().getMetaDataForMember(fieldName));
            orderDirs[i] = !orderComponents[i].isForward();
            SQLTable fieldSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), fieldMapping);
            orderExprs[i] = exprFactory.newExpression(sqlStmt, fieldSqlTbl, fieldMapping);
        }
        sqlStmt.setOrdering(orderExprs, orderDirs);
    }
    return new IteratorStatement(this, sqlStmt, stmtClassMapping);
}

Example 9 with StatementClassMapping

use of org.datanucleus.store.rdbms.query.StatementClassMapping in project datanucleus-rdbms by datanucleus.

the class FKListStore method listIterator.

/**
 * Accessor for an iterator through the list elements.
 * @param ownerOP ObjectProvider for the owner.
 * @param startIdx The start index in the list (only for indexed lists)
 * @param endIdx The end index in the list (only for indexed lists)
 * @return The List Iterator
 */
protected ListIterator<E> listIterator(ObjectProvider ownerOP, int startIdx, int endIdx) {
    ExecutionContext ec = ownerOP.getExecutionContext();
    Transaction tx = ec.getTransaction();
    if (elementInfo == null || elementInfo.length == 0) {
        return null;
    }
    // Generate the statement. Note that this is not cached since depends on the current FetchPlan and other things
    IteratorStatement iterStmt = getIteratorStatement(ownerOP.getExecutionContext(), ec.getFetchPlan(), true, startIdx, endIdx);
    SelectStatement sqlStmt = iterStmt.getSelectStatement();
    StatementClassMapping resultMapping = iterStmt.getStatementClassMapping();
    // Input parameter(s) - the owner
    int inputParamNum = 1;
    StatementMappingIndex ownerIdx = new StatementMappingIndex(ownerMapping);
    if (sqlStmt.getNumberOfUnions() > 0) {
        // Add parameter occurrence for each union of statement
        for (int j = 0; j < sqlStmt.getNumberOfUnions() + 1; j++) {
            int[] paramPositions = new int[ownerMapping.getNumberOfDatastoreMappings()];
            for (int k = 0; k < ownerMapping.getNumberOfDatastoreMappings(); k++) {
                paramPositions[k] = inputParamNum++;
            }
            ownerIdx.addParameterOccurrence(paramPositions);
        }
    } else {
        int[] paramPositions = new int[ownerMapping.getNumberOfDatastoreMappings()];
        for (int k = 0; k < ownerMapping.getNumberOfDatastoreMappings(); k++) {
            paramPositions[k] = inputParamNum++;
        }
        ownerIdx.addParameterOccurrence(paramPositions);
    }
    if (tx.getSerializeRead() != null && tx.getSerializeRead()) {
        sqlStmt.addExtension(SQLStatement.EXTENSION_LOCK_FOR_UPDATE, true);
    }
    String stmt = sqlStmt.getSQLText().toSQL();
    try {
        ManagedConnection mconn = storeMgr.getConnectionManager().getConnection(ec);
        SQLController sqlControl = storeMgr.getSQLController();
        try {
            // Create the statement
            PreparedStatement ps = sqlControl.getStatementForQuery(mconn, stmt);
            // Set the owner
            ObjectProvider stmtOwnerOP = BackingStoreHelper.getOwnerObjectProviderForBackingStore(ownerOP);
            int numParams = ownerIdx.getNumberOfParameterOccurrences();
            for (int paramInstance = 0; paramInstance < numParams; paramInstance++) {
                ownerIdx.getMapping().setObject(ec, ps, ownerIdx.getParameterPositionsForOccurrence(paramInstance), stmtOwnerOP.getObject());
            }
            try {
                ResultSet rs = sqlControl.executeStatementQuery(ec, mconn, stmt, ps);
                try {
                    ResultObjectFactory rof = null;
                    if (elementsAreEmbedded || elementsAreSerialised) {
                        throw new NucleusException("Cannot have FK set with non-persistent objects");
                    }
                    rof = new PersistentClassROF(ec, rs, false, resultMapping, elementCmd, clr.classForName(elementType));
                    return new ListStoreIterator(ownerOP, rs, rof, this);
                } finally {
                    rs.close();
                }
            } finally {
                sqlControl.closeStatement(mconn, ps);
            }
        } finally {
            mconn.release();
        }
    } catch (SQLException | MappedDatastoreException e) {
        throw new NucleusDataStoreException(Localiser.msg("056006", stmt), e);
    }
}

Example 10 with StatementClassMapping

use of org.datanucleus.store.rdbms.query.StatementClassMapping in project datanucleus-rdbms by datanucleus.

the class FKMapStore method getSQLStatementForGet.

/**
 * Method to return an SQLStatement for retrieving the value for a key.
 * Selects the join table and optionally joins to the value table if it has its own table.
 * @param ownerOP ObjectProvider for the owning object
 * @return The SQLStatement
 */
protected SelectStatement getSQLStatementForGet(ObjectProvider ownerOP) {
    SelectStatement sqlStmt = null;
    ExecutionContext ec = ownerOP.getExecutionContext();
    final ClassLoaderResolver clr = ownerOP.getExecutionContext().getClassLoaderResolver();
    final Class valueCls = clr.classForName(this.valueType);
    if (ownerMemberMetaData.getMap().getMapType() == MapType.MAP_TYPE_KEY_IN_VALUE) {
        getMappingDef = new StatementClassMapping();
        if (valueTable.getDiscriminatorMetaData() != null && valueTable.getDiscriminatorMetaData().getStrategy() != DiscriminatorStrategy.NONE) {
            // Value class has discriminator
            if (ClassUtils.isReferenceType(valueCls)) {
                String[] clsNames = storeMgr.getNucleusContext().getMetaDataManager().getClassesImplementingInterface(valueType, clr);
                Class[] cls = new Class[clsNames.length];
                for (int i = 0; i < clsNames.length; i++) {
                    cls[i] = clr.classForName(clsNames[i]);
                }
                sqlStmt = new DiscriminatorStatementGenerator(storeMgr, clr, cls, true, null, null).getStatement(ec);
            } else {
                sqlStmt = new DiscriminatorStatementGenerator(storeMgr, clr, valueCls, true, null, null).getStatement(ec);
            }
            iterateUsingDiscriminator = true;
        } else {
            // Use union to resolve any subclasses of value
            UnionStatementGenerator stmtGen = new UnionStatementGenerator(storeMgr, clr, valueCls, true, null, null);
            stmtGen.setOption(SelectStatementGenerator.OPTION_SELECT_DN_TYPE);
            getMappingDef.setNucleusTypeColumnName(UnionStatementGenerator.DN_TYPE_COLUMN);
            sqlStmt = stmtGen.getStatement(ec);
        }
        // Select the value field(s)
        SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(sqlStmt, getMappingDef, ec.getFetchPlan(), sqlStmt.getPrimaryTable(), valueCmd, ec.getFetchPlan().getMaxFetchDepth());
    } else {
        // Value is in key table
        sqlStmt = new SelectStatement(storeMgr, mapTable, null, null);
        sqlStmt.setClassLoaderResolver(clr);
        if (valueCmd != null) {
            // Left outer join to value table (so we allow for null values)
            SQLTable valueSqlTbl = sqlStmt.join(JoinType.LEFT_OUTER_JOIN, sqlStmt.getPrimaryTable(), valueMapping, valueTable, null, valueTable.getIdMapping(), null, null, true);
            // Select the value field(s)
            SQLStatementHelper.selectFetchPlanOfSourceClassInStatement(sqlStmt, getMappingDef, ec.getFetchPlan(), valueSqlTbl, valueCmd, ec.getFetchPlan().getMaxFetchDepth());
        } else {
            sqlStmt.select(sqlStmt.getPrimaryTable(), valueMapping, null);
        }
    }
    // Apply condition on owner field to filter by owner
    SQLExpressionFactory exprFactory = storeMgr.getSQLExpressionFactory();
    SQLTable ownerSqlTbl = SQLStatementHelper.getSQLTableForMappingOfTable(sqlStmt, sqlStmt.getPrimaryTable(), ownerMapping);
    SQLExpression ownerExpr = exprFactory.newExpression(sqlStmt, ownerSqlTbl, ownerMapping);
    SQLExpression ownerVal = exprFactory.newLiteralParameter(sqlStmt, ownerMapping, null, "OWNER");
    sqlStmt.whereAnd(ownerExpr.eq(ownerVal), true);
    // Apply condition on key
    if (keyMapping instanceof SerialisedMapping) {
        // if the keyMapping contains a BLOB column (or any other column not supported by the database
        // as primary key), uses like instead of the operator OP_EQ (=)
        // in future do not check if the keyMapping is of ObjectMapping, but use the database
        // adapter to check the data types not supported as primary key
        // if object mapping (BLOB) use like
        SQLExpression keyExpr = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), keyMapping);
        SQLExpression keyVal = exprFactory.newLiteralParameter(sqlStmt, keyMapping, null, "KEY");
        sqlStmt.whereAnd(new org.datanucleus.store.rdbms.sql.expression.BooleanExpression(keyExpr, Expression.OP_LIKE, keyVal), true);
    } else {
        SQLExpression keyExpr = exprFactory.newExpression(sqlStmt, sqlStmt.getPrimaryTable(), keyMapping);
        SQLExpression keyVal = exprFactory.newLiteralParameter(sqlStmt, keyMapping, null, "KEY");
        sqlStmt.whereAnd(keyExpr.eq(keyVal), true);
    }
    // Input parameter(s) - owner, key
    int inputParamNum = 1;
    StatementMappingIndex ownerIdx = new StatementMappingIndex(ownerMapping);
    StatementMappingIndex keyIdx = new StatementMappingIndex(keyMapping);
    if (sqlStmt.getNumberOfUnions() > 0) {
        // Add parameter occurrence for each union of statement
        for (int j = 0; j < sqlStmt.getNumberOfUnions() + 1; j++) {
            int[] ownerPositions = new int[ownerMapping.getNumberOfDatastoreMappings()];
            for (int k = 0; k < ownerPositions.length; k++) {
                ownerPositions[k] = inputParamNum++;
            }
            ownerIdx.addParameterOccurrence(ownerPositions);
            int[] keyPositions = new int[keyMapping.getNumberOfDatastoreMappings()];
            for (int k = 0; k < keyPositions.length; k++) {
                keyPositions[k] = inputParamNum++;
            }
            keyIdx.addParameterOccurrence(keyPositions);
        }
    } else {
        int[] ownerPositions = new int[ownerMapping.getNumberOfDatastoreMappings()];
        for (int k = 0; k < ownerPositions.length; k++) {
            ownerPositions[k] = inputParamNum++;
        }
        ownerIdx.addParameterOccurrence(ownerPositions);
        int[] keyPositions = new int[keyMapping.getNumberOfDatastoreMappings()];
        for (int k = 0; k < keyPositions.length; k++) {
            keyPositions[k] = inputParamNum++;
        }
        keyIdx.addParameterOccurrence(keyPositions);
    }
    getMappingParams = new StatementParameterMapping();
    getMappingParams.addMappingForParameter("owner", ownerIdx);
    getMappingParams.addMappingForParameter("key", keyIdx);
    return sqlStmt;
}