Examples with JoinOp herddb.model.planner.JoinOp used on opensource projects

Example 1 with JoinOp

use of herddb.model.planner.JoinOp in project herddb by diennea.

the class CalcitePlanner method planEnumerableJoin.

private PlannerOp planEnumerableJoin(EnumerableJoin op, RelDataType rowType) {
    // please note that EnumerableJoin has a condition field which actually is not useful
    PlannerOp left = convertRelNode(op.getLeft(), null, false);
    PlannerOp right = convertRelNode(op.getRight(), null, false);
    int[] leftKeys = op.getLeftKeys().toIntArray();
    int[] rightKeys = op.getRightKeys().toIntArray();
    boolean generateNullsOnLeft = op.getJoinType().generatesNullsOnLeft();
    boolean generateNullsOnRight = op.getJoinType().generatesNullsOnRight();
    final RelDataType _rowType = rowType == null ? op.getRowType() : rowType;
    List<RelDataTypeField> fieldList = _rowType.getFieldList();
    Column[] columns = new Column[fieldList.size()];
    String[] fieldNames = new String[columns.length];
    int i = 0;
    for (RelDataTypeField field : fieldList) {
        Column col = Column.column(field.getName().toLowerCase(), convertToHerdType(field.getType()));
        fieldNames[i] = col.name;
        columns[i++] = col;
    }
    return new JoinOp(fieldNames, columns, leftKeys, left, rightKeys, right, generateNullsOnLeft, generateNullsOnRight, false);
}

Example 2 with JoinOp

use of herddb.model.planner.JoinOp in project herddb by diennea.

the class SimpleJoinTest method testStartTransactionInJoinBranch.

@Test
public void testStartTransactionInJoinBranch() throws Exception {
    String nodeId = "localhost";
    try (DBManager manager = new DBManager("localhost", new MemoryMetadataStorageManager(), new MemoryDataStorageManager(), new MemoryCommitLogManager(), null, null)) {
        manager.start();
        CreateTableSpaceStatement st1 = new CreateTableSpaceStatement("tblspace1", Collections.singleton(nodeId), nodeId, 1, 0, 0);
        manager.executeStatement(st1, StatementEvaluationContext.DEFAULT_EVALUATION_CONTEXT(), TransactionContext.NO_TRANSACTION);
        manager.waitForTablespace("tblspace1", 10000);
        execute(manager, "CREATE TABLE tblspace1.table1 (k1 string primary key,n1 int,s1 string)", Collections.emptyList());
        execute(manager, "CREATE TABLE tblspace1.table2 (k2 string primary key,n2 int,s2 string)", Collections.emptyList());
        execute(manager, "INSERT INTO tblspace1.table1 (k1,n1,s1) values('a',1,'A')", Collections.emptyList());
        execute(manager, "INSERT INTO tblspace1.table1 (k1,n1,s1) values('b',2,'B')", Collections.emptyList());
        execute(manager, "INSERT INTO tblspace1.table2 (k2,n2,s2) values('c',3,'A')", Collections.emptyList());
        execute(manager, "INSERT INTO tblspace1.table2 (k2,n2,s2) values('d',4,'A')", Collections.emptyList());
        {
            TranslatedQuery translated = manager.getPlanner().translate(TableSpace.DEFAULT, "SELECT * FROM" + " tblspace1.table1 t1" + " JOIN tblspace1.table2 t2" + " ON t1.n1 > 0" + "   and t2.n2 >= 1", Collections.emptyList(), true, true, false, -1);
            translated.context.setForceRetainReadLock(true);
            if (manager.getPlanner() instanceof CalcitePlanner) {
                assertThat(translated.plan.originalRoot, instanceOf(NestedLoopJoinOp.class));
                NestedLoopJoinOp join = (NestedLoopJoinOp) translated.plan.originalRoot;
                assertThat(join.getLeft(), instanceOf(SimpleScanOp.class));
                assertThat(join.getRight(), instanceOf(SimpleScanOp.class));
            }
            // we want that the left branch of the join starts the transactoion
            ScanResult scanResult = ((ScanResult) manager.executePlan(translated.plan, translated.context, TransactionContext.AUTOTRANSACTION_TRANSACTION));
            List<DataAccessor> tuples = scanResult.dataScanner.consumeAndClose();
            assertTrue(scanResult.transactionId > 0);
            for (DataAccessor t : tuples) {
                System.out.println("t:" + t);
                assertEquals(6, t.getFieldNames().length);
                assertEquals("k1", t.getFieldNames()[0]);
                assertEquals("n1", t.getFieldNames()[1]);
                assertEquals("s1", t.getFieldNames()[2]);
                assertEquals("k2", t.getFieldNames()[3]);
                assertEquals("n2", t.getFieldNames()[4]);
                assertEquals("s2", t.getFieldNames()[5]);
            }
            assertEquals(4, tuples.size());
            TestUtils.commitTransaction(manager, "tblspace1", scanResult.transactionId);
        }
        {
            TranslatedQuery translated = manager.getPlanner().translate(TableSpace.DEFAULT, "SELECT * FROM" + " tblspace1.table1 t1" + " JOIN tblspace1.table2 t2" + " ON t1.n1 > 0" + "   and t2.n2 >= 1" + "   order by t1.n1, t2.n2", Collections.emptyList(), true, true, false, // with order by
            -1);
            translated.context.setForceRetainReadLock(true);
            assertThat(translated.plan.originalRoot, instanceOf(SortOp.class));
            if (manager.getPlanner() instanceof CalcitePlanner) {
                NestedLoopJoinOp join = (NestedLoopJoinOp) ((SortOp) translated.plan.originalRoot).getInput();
                assertThat(join.getLeft(), instanceOf(SimpleScanOp.class));
                assertThat(join.getRight(), instanceOf(SimpleScanOp.class));
            } else {
                JoinOp join = (JoinOp) ((SortOp) translated.plan.originalRoot).getInput();
                assertThat(join.getLeft(), instanceOf(SimpleScanOp.class));
                assertThat(join.getRight(), instanceOf(SimpleScanOp.class));
            }
            // we want that the left branch of the join starts the transactoion
            ScanResult scanResult = ((ScanResult) manager.executePlan(translated.plan, translated.context, TransactionContext.AUTOTRANSACTION_TRANSACTION));
            List<DataAccessor> tuples = scanResult.dataScanner.consumeAndClose();
            assertTrue(scanResult.transactionId > 0);
            for (DataAccessor t : tuples) {
                System.out.println("t:" + t);
                assertEquals(6, t.getFieldNames().length);
                assertEquals("k1", t.getFieldNames()[0]);
                assertEquals("n1", t.getFieldNames()[1]);
                assertEquals("s1", t.getFieldNames()[2]);
                assertEquals("k2", t.getFieldNames()[3]);
                assertEquals("n2", t.getFieldNames()[4]);
                assertEquals("s2", t.getFieldNames()[5]);
            }
            assertEquals(4, tuples.size());
            TestUtils.commitTransaction(manager, "tblspace1", scanResult.transactionId);
        }
        {
            TranslatedQuery translated = manager.getPlanner().translate(TableSpace.DEFAULT, "SELECT t1.s1 FROM" + " tblspace1.table1 t1" + " JOIN tblspace1.table2 t2" + " ON t1.n1 > 0" + "   and t2.n2 >= 1" + "   order by t1.n1, t2.n2", Collections.emptyList(), true, true, false, // with order by on non selected fields
            -1);
            translated.context.setForceRetainReadLock(true);
            assertThat(translated.plan.originalRoot, instanceOf(ProjectOp.class));
            SortOp sort = (SortOp) ((ProjectOp) translated.plan.originalRoot).getInput();
            assertThat(((ProjectOp) translated.plan.originalRoot).getProjection(), instanceOf(ProjectOp.ZeroCopyProjection.class));
            if (manager.getPlanner() instanceof CalcitePlanner) {
                NestedLoopJoinOp join = (NestedLoopJoinOp) sort.getInput();
                assertThat(join.getLeft(), instanceOf(SimpleScanOp.class));
                assertThat(join.getRight(), instanceOf(SimpleScanOp.class));
            } else {
                JoinOp join = (JoinOp) sort.getInput();
                assertThat(join.getLeft(), instanceOf(SimpleScanOp.class));
                assertThat(join.getRight(), instanceOf(SimpleScanOp.class));
            }
            // we want that the left branch of the join starts the transactoion
            ScanResult scanResult = ((ScanResult) manager.executePlan(translated.plan, translated.context, TransactionContext.AUTOTRANSACTION_TRANSACTION));
            List<DataAccessor> tuples = scanResult.dataScanner.consumeAndClose();
            assertTrue(scanResult.transactionId > 0);
            for (DataAccessor t : tuples) {
                System.out.println("t:" + t);
                assertEquals(1, t.getFieldNames().length);
                assertEquals("s1", t.getFieldNames()[0]);
            }
            assertEquals(4, tuples.size());
            TestUtils.commitTransaction(manager, "tblspace1", scanResult.transactionId);
        }
    }
}

Example 3 with JoinOp

use of herddb.model.planner.JoinOp in project herddb by diennea.

the class CalcitePlanner method planEnumerableMergeJoin.

private PlannerOp planEnumerableMergeJoin(EnumerableMergeJoin op, RelDataType rowType) {
    // please note that EnumerableMergeJoin has a condition field which actually is not useful
    PlannerOp left = convertRelNode(op.getLeft(), null, false, false);
    PlannerOp right = convertRelNode(op.getRight(), null, false, false);
    final JoinInfo analyzeCondition = op.analyzeCondition();
    int[] leftKeys = analyzeCondition.leftKeys.toIntArray();
    int[] rightKeys = analyzeCondition.rightKeys.toIntArray();
    boolean generateNullsOnLeft = op.getJoinType().generatesNullsOnLeft();
    boolean generateNullsOnRight = op.getJoinType().generatesNullsOnRight();
    final RelDataType _rowType = rowType == null ? op.getRowType() : rowType;
    List<CompiledSQLExpression> nonEquiConditions = convertJoinNonEquiConditions(analyzeCondition);
    List<RelDataTypeField> fieldList = _rowType.getFieldList();
    Column[] columns = new Column[fieldList.size()];
    String[] fieldNames = new String[columns.length];
    int i = 0;
    for (RelDataTypeField field : fieldList) {
        Column col = Column.column(field.getName().toLowerCase(), convertToHerdType(field.getType()));
        fieldNames[i] = col.name;
        columns[i++] = col;
    }
    return new JoinOp(fieldNames, columns, leftKeys, left, rightKeys, right, generateNullsOnLeft, generateNullsOnRight, true, nonEquiConditions);
}

Example 4 with JoinOp

use of herddb.model.planner.JoinOp in project herddb by diennea.

the class CalcitePlanner method planEnumerableHashJoin.

private PlannerOp planEnumerableHashJoin(EnumerableHashJoin op, RelDataType rowType) {
    // please note that EnumerableSemiJoin has a condition field which actually is not useful
    PlannerOp left = convertRelNode(op.getLeft(), null, false, false);
    PlannerOp right = convertRelNode(op.getRight(), null, false, false);
    final JoinInfo analyzeCondition = op.analyzeCondition();
    int[] leftKeys = analyzeCondition.leftKeys.toIntArray();
    int[] rightKeys = analyzeCondition.rightKeys.toIntArray();
    boolean generateNullsOnLeft = op.getJoinType().generatesNullsOnLeft();
    boolean generateNullsOnRight = op.getJoinType().generatesNullsOnRight();
    List<CompiledSQLExpression> nonEquiConditions = convertJoinNonEquiConditions(analyzeCondition);
    final RelDataType _rowType = rowType == null ? op.getRowType() : rowType;
    List<RelDataTypeField> fieldList = _rowType.getFieldList();
    Column[] columns = new Column[fieldList.size()];
    String[] fieldNames = new String[columns.length];
    int i = 0;
    for (RelDataTypeField field : fieldList) {
        Column col = Column.column(field.getName().toLowerCase(), convertToHerdType(field.getType()));
        fieldNames[i] = col.name;
        columns[i++] = col;
    }
    if (op.isSemiJoin()) {
        return new SemiJoinOp(fieldNames, columns, leftKeys, left, rightKeys, right);
    } else {
        return new JoinOp(fieldNames, columns, leftKeys, left, rightKeys, right, generateNullsOnLeft, generateNullsOnRight, false, nonEquiConditions);
    }
}

Example 5 with JoinOp

use of herddb.model.planner.JoinOp in project herddb by diennea.

the class JSQLParserPlanner method buildSelectBody.

private PlannerOp buildSelectBody(String defaultTableSpace, int maxRows, SelectBody selectBody, boolean forceScan) throws StatementExecutionException {
    if (selectBody instanceof SetOperationList) {
        SetOperationList list = (SetOperationList) selectBody;
        return buildSetOperationList(defaultTableSpace, maxRows, list, forceScan);
    }
    checkSupported(selectBody instanceof PlainSelect, selectBody.getClass().getName());
    PlainSelect plainSelect = (PlainSelect) selectBody;
    checkSupported(!plainSelect.getMySqlHintStraightJoin());
    checkSupported(!plainSelect.getMySqlSqlCalcFoundRows());
    checkSupported(!plainSelect.getMySqlSqlNoCache());
    checkSupported(plainSelect.getDistinct() == null);
    checkSupported(plainSelect.getFetch() == null);
    checkSupported(plainSelect.getFirst() == null);
    checkSupported(plainSelect.getForUpdateTable() == null);
    checkSupported(plainSelect.getForXmlPath() == null);
    checkSupported(plainSelect.getHaving() == null);
    checkSupported(plainSelect.getIntoTables() == null);
    checkSupported(plainSelect.getOffset() == null);
    checkSupported(plainSelect.getOptimizeFor() == null);
    checkSupported(plainSelect.getOracleHierarchical() == null);
    checkSupported(plainSelect.getOracleHint() == null);
    checkSupported(plainSelect.getSkip() == null);
    checkSupported(plainSelect.getWait() == null);
    checkSupported(plainSelect.getKsqlWindow() == null);
    FromItem fromItem = plainSelect.getFromItem();
    checkSupported(fromItem instanceof net.sf.jsqlparser.schema.Table);
    OpSchema primaryTableSchema = getTableSchema(defaultTableSpace, (net.sf.jsqlparser.schema.Table) fromItem);
    OpSchema[] joinedTables = new OpSchema[0];
    int totalJoinOutputFieldsCount = primaryTableSchema.columns.length;
    if (plainSelect.getJoins() != null) {
        joinedTables = new OpSchema[plainSelect.getJoins().size()];
        int i = 0;
        for (Join join : plainSelect.getJoins()) {
            checkSupported(!join.isApply());
            checkSupported(!join.isCross());
            checkSupported(!join.isFull() || (join.isFull() && join.isOuter()));
            checkSupported(!join.isSemi());
            checkSupported(!join.isStraight());
            checkSupported(!join.isWindowJoin());
            checkSupported(join.getJoinWindow() == null);
            checkSupported(join.getUsingColumns() == null);
            FromItem rightItem = join.getRightItem();
            checkSupported(rightItem instanceof net.sf.jsqlparser.schema.Table);
            OpSchema joinedTable = getTableSchema(defaultTableSpace, (net.sf.jsqlparser.schema.Table) rightItem);
            joinedTables[i++] = joinedTable;
            totalJoinOutputFieldsCount += joinedTable.columns.length;
        }
    }
    int pos = 0;
    String[] joinOutputFieldnames = new String[totalJoinOutputFieldsCount];
    ColumnRef[] joinOutputColumns = new ColumnRef[totalJoinOutputFieldsCount];
    System.arraycopy(primaryTableSchema.columnNames, 0, joinOutputFieldnames, 0, primaryTableSchema.columnNames.length);
    System.arraycopy(primaryTableSchema.columns, 0, joinOutputColumns, 0, primaryTableSchema.columns.length);
    pos += primaryTableSchema.columnNames.length;
    for (OpSchema joinedTable : joinedTables) {
        System.arraycopy(joinedTable.columnNames, 0, joinOutputFieldnames, pos, joinedTable.columnNames.length);
        System.arraycopy(joinedTable.columns, 0, joinOutputColumns, pos, joinedTable.columns.length);
        pos += joinedTable.columnNames.length;
    }
    OpSchema currentSchema = primaryTableSchema;
    // single JOIN only at the moment
    checkSupported(joinedTables.length <= 1);
    if (joinedTables.length > 0) {
        currentSchema = new OpSchema(primaryTableSchema.tableSpace, null, null, joinOutputFieldnames, joinOutputColumns);
    }
    List<SelectItem> selectItems = plainSelect.getSelectItems();
    checkSupported(!selectItems.isEmpty());
    Predicate predicate = null;
    TupleComparator comparator = null;
    ScanLimits limits = null;
    boolean identityProjection = false;
    Projection projection;
    List<SelectExpressionItem> selectedFields = new ArrayList<>(selectItems.size());
    boolean containsAggregatedFunctions = false;
    if (selectItems.size() == 1 && selectItems.get(0) instanceof AllColumns) {
        projection = Projection.IDENTITY(currentSchema.columnNames, ColumnRef.toColumnsArray(currentSchema.columns));
        identityProjection = true;
    } else {
        checkSupported(!selectItems.isEmpty());
        for (SelectItem item : selectItems) {
            if (item instanceof SelectExpressionItem) {
                SelectExpressionItem selectExpressionItem = (SelectExpressionItem) item;
                selectedFields.add(selectExpressionItem);
                if (SQLParserExpressionCompiler.detectAggregatedFunction(selectExpressionItem.getExpression()) != null) {
                    containsAggregatedFunctions = true;
                }
            } else if (item instanceof AllTableColumns) {
                // expand  alias.* to the full list of columns (according to pyhsical schema!)
                AllTableColumns allTablesColumn = (AllTableColumns) item;
                net.sf.jsqlparser.schema.Table table = allTablesColumn.getTable();
                String tableName = fixMySqlBackTicks(table.getName());
                boolean found = false;
                if (primaryTableSchema.isTableOrAlias(tableName)) {
                    for (ColumnRef col : primaryTableSchema.columns) {
                        net.sf.jsqlparser.schema.Column c = new net.sf.jsqlparser.schema.Column(table, col.name);
                        SelectExpressionItem selectExpressionItem = new SelectExpressionItem(c);
                        selectedFields.add(selectExpressionItem);
                        found = true;
                    }
                } else {
                    for (OpSchema joinedTableSchema : joinedTables) {
                        if (joinedTableSchema.isTableOrAlias(tableName)) {
                            for (ColumnRef col : joinedTableSchema.columns) {
                                net.sf.jsqlparser.schema.Column c = new net.sf.jsqlparser.schema.Column(table, col.name);
                                SelectExpressionItem selectExpressionItem = new SelectExpressionItem(c);
                                selectedFields.add(selectExpressionItem);
                            }
                            found = true;
                            break;
                        }
                    }
                }
                if (!found) {
                    checkSupported(false, "Bad table ref " + tableName + ".*");
                }
            } else {
                checkSupported(false);
            }
        }
        if (!containsAggregatedFunctions) {
            // building the projection
            // we have the current physical schema, we can create references by position (as Calcite does)
            // in order to not need accessing columns by name and also making it easier to support
            // ZeroCopyProjections
            projection = buildProjection(selectedFields, true, currentSchema);
        } else {
            // start by full table scan, the AggregateOp operator will create the final projection
            projection = Projection.IDENTITY(currentSchema.columnNames, ColumnRef.toColumnsArray(currentSchema.columns));
            identityProjection = true;
        }
    }
    TableSpaceManager tableSpaceManager = this.manager.getTableSpaceManager(primaryTableSchema.tableSpace);
    AbstractTableManager tableManager = tableSpaceManager.getTableManager(primaryTableSchema.name);
    Table tableImpl = tableManager.getTable();
    CompiledSQLExpression whereExpression = null;
    if (plainSelect.getWhere() != null) {
        whereExpression = SQLParserExpressionCompiler.compileExpression(plainSelect.getWhere(), currentSchema);
        if (joinedTables.length == 0 && whereExpression != null) {
            SQLRecordPredicate sqlWhere = new SQLRecordPredicate(tableImpl, null, whereExpression);
            IndexUtils.discoverIndexOperations(primaryTableSchema.tableSpace, whereExpression, tableImpl, sqlWhere, selectBody, tableSpaceManager);
            predicate = sqlWhere;
        }
    }
    // start with a TableScan + filters
    ScanStatement scan = new ScanStatement(primaryTableSchema.tableSpace, primaryTableSchema.name, Projection.IDENTITY(primaryTableSchema.columnNames, ColumnRef.toColumnsArray(primaryTableSchema.columns)), predicate, comparator, limits);
    scan.setTableDef(tableImpl);
    PlannerOp op = new BindableTableScanOp(scan);
    PlannerOp[] scanJoinedTables = new PlannerOp[joinedTables.length];
    int ji = 0;
    for (OpSchema joinedTable : joinedTables) {
        ScanStatement scanSecondaryTable = new ScanStatement(joinedTable.tableSpace, joinedTable.name, Projection.IDENTITY(joinedTable.columnNames, ColumnRef.toColumnsArray(joinedTable.columns)), null, null, null);
        scan.setTableDef(tableImpl);
        checkSupported(joinedTable.tableSpace.equalsIgnoreCase(primaryTableSchema.tableSpace));
        PlannerOp opSecondaryTable = new BindableTableScanOp(scanSecondaryTable);
        scanJoinedTables[ji++] = opSecondaryTable;
    }
    if (scanJoinedTables.length > 0) {
        // assuming only one JOIN clause
        Join joinClause = plainSelect.getJoins().get(0);
        List<CompiledSQLExpression> joinConditions = new ArrayList<>();
        if (joinClause.isNatural()) {
            // NATURAL join adds a constraint on every column with the same name
            List<CompiledSQLExpression> naturalJoinConstraints = new ArrayList<>();
            int posInRowLeft = 0;
            for (ColumnRef ref : primaryTableSchema.columns) {
                int posInRowRight = primaryTableSchema.columns.length;
                for (ColumnRef ref2 : joinedTables[0].columns) {
                    // assuming only one join
                    if (ref2.name.equalsIgnoreCase(ref.name)) {
                        CompiledSQLExpression equals = new CompiledEqualsExpression(new AccessCurrentRowExpression(posInRowLeft, ref.type), new AccessCurrentRowExpression(posInRowRight, ref2.type));
                        naturalJoinConstraints.add(equals);
                    }
                    posInRowRight++;
                }
                posInRowLeft++;
            }
            CompiledSQLExpression naturalJoin = new CompiledMultiAndExpression(naturalJoinConstraints.toArray(new CompiledSQLExpression[0]));
            joinConditions.add(naturalJoin);
        }
        // handle "ON" clause
        Expression onExpression = joinClause.getOnExpression();
        if (onExpression != null) {
            // TODO: this works for INNER join, but not for LEFT/RIGHT joins
            CompiledSQLExpression onCondition = SQLParserExpressionCompiler.compileExpression(onExpression, currentSchema);
            joinConditions.add(onCondition);
        }
        op = new JoinOp(joinOutputFieldnames, ColumnRef.toColumnsArray(joinOutputColumns), new int[0], op, new int[0], scanJoinedTables[0], // generateNullsOnLeft
        joinClause.isRight() || (joinClause.isFull() && joinClause.isOuter()), // generateNullsOnRight
        joinClause.isLeft() || (joinClause.isFull() && joinClause.isOuter()), // mergeJoin
        false, // "ON" conditions
        joinConditions);
        // handle "WHERE" in case of JOIN
        if (whereExpression != null) {
            op = new FilterOp(op, whereExpression);
        }
    }
    // add aggregations
    if (containsAggregatedFunctions) {
        checkSupported(scanJoinedTables.length == 0);
        op = planAggregate(selectedFields, currentSchema, op, currentSchema, plainSelect.getGroupBy());
        currentSchema = new OpSchema(currentSchema.tableSpace, currentSchema.name, currentSchema.alias, ColumnRef.toColumnsRefsArray(currentSchema.name, op.getOutputSchema()));
    }
    // add order by
    if (plainSelect.getOrderByElements() != null) {
        op = planSort(op, currentSchema, plainSelect.getOrderByElements());
    }
    // add limit
    if (plainSelect.getLimit() != null) {
        checkSupported(scanJoinedTables.length == 0);
        // cannot mix LIMIT and TOP
        checkSupported(plainSelect.getTop() == null);
        Limit limit = plainSelect.getLimit();
        CompiledSQLExpression offset;
        if (limit.getOffset() != null) {
            offset = SQLParserExpressionCompiler.compileExpression(limit.getOffset(), currentSchema);
        } else {
            offset = new ConstantExpression(0, ColumnTypes.NOTNULL_LONG);
        }
        CompiledSQLExpression rowCount = null;
        if (limit.getRowCount() != null) {
            rowCount = SQLParserExpressionCompiler.compileExpression(limit.getRowCount(), currentSchema);
        }
        op = new LimitOp(op, rowCount, offset);
    }
    if (plainSelect.getTop() != null) {
        checkSupported(scanJoinedTables.length == 0);
        // cannot mix LIMIT and TOP
        checkSupported(plainSelect.getLimit() == null);
        Top limit = plainSelect.getTop();
        CompiledSQLExpression rowCount = null;
        if (limit.getExpression() != null) {
            rowCount = SQLParserExpressionCompiler.compileExpression(limit.getExpression(), currentSchema);
        }
        op = new LimitOp(op, rowCount, new ConstantExpression(0, ColumnTypes.NOTNULL_LONG));
    }
    if (!containsAggregatedFunctions && !identityProjection) {
        // add projection
        op = new ProjectOp(projection, op);
    }
    // additional maxrows from JDBC PreparedStatement
    if (maxRows > 0) {
        op = new LimitOp(op, new ConstantExpression(maxRows, ColumnTypes.NOTNULL_LONG), new ConstantExpression(0, ColumnTypes.NOTNULL_LONG)).optimize();
    }
    return op;
}