/*
* Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
* Version 1.0, and under the Eclipse Public License, Version 1.0
* (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.table;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import org.h2.constant.ErrorCode;
import org.h2.engine.Session;
import org.h2.expression.Expression;
import org.h2.expression.FunctionCall;
import org.h2.expression.TableFunction;
import org.h2.index.FunctionIndex;
import org.h2.index.Index;
import org.h2.index.IndexType;
import org.h2.message.DbException;
import org.h2.result.LocalResult;
import org.h2.result.ResultInterface;
import org.h2.result.Row;
import org.h2.schema.Schema;
import org.h2.value.DataType;
import org.h2.value.Value;
import org.h2.value.ValueNull;
import org.h2.value.ValueResultSet;
/**
* A table backed by a system or user-defined function that returns a result set.
*/
public class FunctionTable extends Table {
private final FunctionCall function;
private final long rowCount;
private Expression functionExpr;
private LocalResult cachedResult;
private Value cachedValue;
public FunctionTable(Schema schema, Session session, Expression functionExpr, FunctionCall function) {
super(schema, 0, function.getName(), false, true);
this.functionExpr = functionExpr;
this.function = function;
if (function instanceof TableFunction) {
rowCount = ((TableFunction) function).getRowCount();
} else {
rowCount = Long.MAX_VALUE;
}
function.optimize(session);
int type = function.getType();
if (type != Value.RESULT_SET) {
throw DbException.get(ErrorCode.FUNCTION_MUST_RETURN_RESULT_SET_1, function.getName());
}
int params = function.getParameterCount();
Expression[] columnListArgs = new Expression[params];
Expression[] args = function.getArgs();
for (int i = 0; i < params; i++) {
args[i] = args[i].optimize(session);
columnListArgs[i] = args[i];
}
ValueResultSet template = function.getValueForColumnList(session, columnListArgs);
if (template == null) {
throw DbException.get(ErrorCode.FUNCTION_MUST_RETURN_RESULT_SET_1, function.getName());
}
ResultSet rs = template.getResultSet();
try {
ResultSetMetaData meta = rs.getMetaData();
int columnCount = meta.getColumnCount();
Column[] cols = new Column[columnCount];
for (int i = 0; i < columnCount; i++) {
cols[i] = new Column(meta.getColumnName(i + 1), DataType.convertSQLTypeToValueType(meta
.getColumnType(i + 1)), meta.getPrecision(i + 1), meta.getScale(i + 1), meta.getColumnDisplaySize(i + 1));
}
setColumns(cols);
} catch (SQLException e) {
throw DbException.convert(e);
}
}
public void lock(Session session, boolean exclusive, boolean force) {
// nothing to do
}
public void close(Session session) {
// nothing to do
}
public void unlock(Session s) {
// nothing to do
}
public boolean isLockedExclusively() {
return false;
}
public Index addIndex(Session session, String indexName, int indexId, IndexColumn[] cols, IndexType indexType,
boolean create, String indexComment) {
throw DbException.getUnsupportedException("ALIAS");
}
public void removeRow(Session session, Row row) {
throw DbException.getUnsupportedException("ALIAS");
}
public void truncate(Session session) {
throw DbException.getUnsupportedException("ALIAS");
}
public boolean canDrop() {
throw DbException.throwInternalError();
}
public void addRow(Session session, Row row) {
throw DbException.getUnsupportedException("ALIAS");
}
public void checkSupportAlter() {
throw DbException.getUnsupportedException("ALIAS");
}
public String getTableType() {
return null;
}
public Index getScanIndex(Session session) {
return new FunctionIndex(this, IndexColumn.wrap(columns));
}
public ArrayList<Index> getIndexes() {
return null;
}
public boolean canGetRowCount() {
return rowCount != Long.MAX_VALUE;
}
public long getRowCount(Session session) {
return rowCount;
}
public String getCreateSQL() {
return null;
}
public String getDropSQL() {
return null;
}
public void checkRename() {
throw DbException.getUnsupportedException("ALIAS");
}
/**
* Read the result from the function. This method caches the result.
*
* @param session the session
* @return the result
*/
public ResultInterface getResult(Session session) {
ValueResultSet v = getValueResultSet(session);
if (v == null) {
return null;
}
if (cachedResult != null && cachedValue == v) {
cachedResult.reset();
return cachedResult;
}
LocalResult result = LocalResult.read(session, v.getResultSet(), 0);
if (function.isDeterministic()) {
cachedResult = result;
cachedValue = v;
}
return result;
}
/**
* Read the result set from the function. This method doesn't cache.
*
* @param session the session
* @return the result set
*/
public ResultSet getResultSet(Session session) {
ValueResultSet v = getValueResultSet(session);
return v == null ? null : v.getResultSet();
}
private ValueResultSet getValueResultSet(Session session) {
functionExpr = functionExpr.optimize(session);
Value v = functionExpr.getValue(session);
if (v == ValueNull.INSTANCE) {
return null;
}
return (ValueResultSet) v;
}
public boolean isFast() {
return function.isFast();
}
public long getMaxDataModificationId() {
// TODO optimization: table-as-a-function currently doesn't know the
// last modified date
return Long.MAX_VALUE;
}
public Index getUniqueIndex() {
return null;
}
public String getSQL() {
return function.getSQL();
}
public long getRowCountApproximation() {
return rowCount;
}
public boolean isDeterministic() {
return function.isDeterministic();
}
public boolean canReference() {
return false;
}
}