net.hydromatic.optiq.prepare.RelOptTableImpl.java Source code

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Here is the source code for net.hydromatic.optiq.prepare.RelOptTableImpl.java

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

import net.hydromatic.linq4j.expressions.Expression;

import net.hydromatic.optiq.QueryableTable;
import net.hydromatic.optiq.Schemas;
import net.hydromatic.optiq.Table;
import net.hydromatic.optiq.TranslatableTable;
import net.hydromatic.optiq.jdbc.OptiqSchema;
import net.hydromatic.optiq.rules.java.EnumerableConvention;
import net.hydromatic.optiq.rules.java.JavaRules;

import org.eigenbase.rel.RelCollation;
import org.eigenbase.rel.RelNode;
import org.eigenbase.relopt.RelOptCluster;
import org.eigenbase.relopt.RelOptSchema;
import org.eigenbase.reltype.RelDataType;
import org.eigenbase.sql.SqlAccessType;
import org.eigenbase.sql.validate.SqlMonotonicity;
import org.eigenbase.util.Util;

import com.google.common.base.Function;
import com.google.common.base.Functions;
import com.google.common.collect.ImmutableList;

import java.lang.reflect.Type;
import java.util.BitSet;
import java.util.Collections;
import java.util.List;

/**
 * Implementation of {@link org.eigenbase.relopt.RelOptTable}.
 */
public class RelOptTableImpl implements Prepare.PreparingTable {
    private final RelOptSchema schema;
    private final RelDataType rowType;
    private final Table table;
    private final Function<Class, Expression> expressionFunction;
    private final ImmutableList<String> names;

    /** Estimate for the row count, or null.
     *
     * <p>If not null, overrides the estimate from the actual table.
     *
     * <p>Useful when a table that contains a materialized query result is being
     * used to replace a query expression that wildly underestimates the row
     * count. Now the materialized table can tell the same lie. */
    private final Double rowCount;

    private RelOptTableImpl(RelOptSchema schema, RelDataType rowType, List<String> names, Table table,
            Function<Class, Expression> expressionFunction, Double rowCount) {
        this.schema = schema;
        this.rowType = rowType;
        this.names = ImmutableList.copyOf(names);
        this.table = table; // may be null
        this.expressionFunction = expressionFunction;
        this.rowCount = rowCount;
        assert expressionFunction != null;
        assert rowType != null;
    }

    public static RelOptTableImpl create(RelOptSchema schema, RelDataType rowType, List<String> names,
            Expression expression) {
        //noinspection unchecked
        final Function<Class, Expression> expressionFunction = (Function) Functions.constant(expression);
        return new RelOptTableImpl(schema, rowType, names, null, expressionFunction, null);
    }

    public static RelOptTableImpl create(RelOptSchema schema, RelDataType rowType,
            final OptiqSchema.TableEntry tableEntry, Double rowCount) {
        Function<Class, Expression> expressionFunction;
        if (tableEntry.getTable() instanceof QueryableTable) {
            final QueryableTable table = (QueryableTable) tableEntry.getTable();
            expressionFunction = new Function<Class, Expression>() {
                public Expression apply(Class clazz) {
                    return table.getExpression(tableEntry.schema.plus(), tableEntry.name, clazz);
                }
            };
        } else {
            expressionFunction = new Function<Class, Expression>() {
                public Expression apply(Class input) {
                    throw new UnsupportedOperationException();
                }
            };
        }
        return new RelOptTableImpl(schema, rowType, tableEntry.path(), tableEntry.getTable(), expressionFunction,
                rowCount);
    }

    public static RelOptTableImpl create(RelOptSchema schema, RelDataType rowType, TranslatableTable table) {
        final Function<Class, Expression> expressionFunction = new Function<Class, Expression>() {
            public Expression apply(Class input) {
                throw new UnsupportedOperationException();
            }
        };
        return new RelOptTableImpl(schema, rowType, ImmutableList.<String>of(), table, expressionFunction, null);
    }

    public <T> T unwrap(Class<T> clazz) {
        if (clazz.isInstance(this)) {
            return clazz.cast(this);
        }
        if (clazz.isInstance(table)) {
            return clazz.cast(table);
        }
        if (clazz == OptiqSchema.class) {
            return clazz.cast(
                    Schemas.subSchema(((OptiqCatalogReader) schema).rootSchema, Util.skipLast(getQualifiedName())));
        }
        return null;
    }

    public Expression getExpression(Class clazz) {
        return expressionFunction.apply(clazz);
    }

    public double getRowCount() {
        if (rowCount != null) {
            return rowCount;
        }
        if (table != null) {
            final Double rowCount = table.getStatistic().getRowCount();
            if (rowCount != null) {
                return rowCount;
            }
        }
        return 100d;
    }

    public RelOptSchema getRelOptSchema() {
        return schema;
    }

    public RelNode toRel(ToRelContext context) {
        if (table instanceof TranslatableTable) {
            return ((TranslatableTable) table).toRel(context, this);
        }
        RelOptCluster cluster = context.getCluster();
        Class elementType = deduceElementType();
        return new JavaRules.EnumerableTableAccessRel(cluster, cluster.traitSetOf(EnumerableConvention.INSTANCE),
                this, elementType);
    }

    private Class deduceElementType() {
        if (table instanceof QueryableTable) {
            final QueryableTable queryableTable = (QueryableTable) table;
            final Type type = queryableTable.getElementType();
            if (type instanceof Class) {
                return (Class) type;
            } else {
                return Object[].class;
            }
        } else {
            return Object.class;
        }
    }

    public List<RelCollation> getCollationList() {
        return Collections.emptyList();
    }

    public boolean isKey(BitSet columns) {
        return table.getStatistic().isKey(columns);
    }

    public RelDataType getRowType() {
        return rowType;
    }

    public List<String> getQualifiedName() {
        return names;
    }

    public SqlMonotonicity getMonotonicity(String columnName) {
        return SqlMonotonicity.NOT_MONOTONIC;
    }

    public SqlAccessType getAllowedAccess() {
        return SqlAccessType.ALL;
    }
}

// End RelOptTableImpl.java