/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.table;
import java.util.ArrayList;
import org.h2.api.ErrorCode;
import org.h2.engine.SessionLocal;
import org.h2.expression.Expression;
import org.h2.index.Index;
import org.h2.index.RangeIndex;
import org.h2.message.DbException;
import org.h2.schema.Schema;
import org.h2.value.TypeInfo;
/**
* The table SYSTEM_RANGE is a virtual table that generates incrementing numbers
* with a given start end point.
*/
public class RangeTable extends VirtualTable {
/**
* The name of the range table.
*/
public static final String NAME = "SYSTEM_RANGE";
/**
* The PostgreSQL alias for the range table.
*/
public static final String ALIAS = "GENERATE_SERIES";
private Expression min, max, step;
private boolean optimized;
private final RangeIndex index;
/**
* Create a new range with the given start and end expressions.
*
* @param schema the schema (always the main schema)
* @param min the start expression
* @param max the end expression
*/
public RangeTable(Schema schema, Expression min, Expression max) {
super(schema, 0, NAME);
this.min = min;
this.max = max;
Column[] columns = new Column[] { new Column("X", TypeInfo.TYPE_BIGINT) };
setColumns(columns);
index = new RangeIndex(this, IndexColumn.wrap(columns));
}
public RangeTable(Schema schema, Expression min, Expression max, Expression step) {
this(schema, min, max);
this.step = step;
}
@Override
public StringBuilder getSQL(StringBuilder builder, int sqlFlags) {
builder.append(NAME).append('(');
min.getUnenclosedSQL(builder, sqlFlags).append(", ");
max.getUnenclosedSQL(builder, sqlFlags);
if (step != null) {
step.getUnenclosedSQL(builder.append(", "), sqlFlags);
}
return builder.append(')');
}
@Override
public boolean canGetRowCount(SessionLocal session) {
return true;
}
@Override
public long getRowCount(SessionLocal session) {
long step = getStep(session);
if (step == 0L) {
throw DbException.get(ErrorCode.STEP_SIZE_MUST_NOT_BE_ZERO);
}
long delta = getMax(session) - getMin(session);
if (step > 0) {
if (delta < 0) {
return 0;
}
} else if (delta > 0) {
return 0;
}
return delta / step + 1;
}
@Override
public TableType getTableType() {
return TableType.SYSTEM_TABLE;
}
@Override
public Index getScanIndex(SessionLocal session) {
return index;
}
@Override
public ArrayList<Index> getIndexes() {
ArrayList<Index> list = new ArrayList<>(2);
// Scan index (ignored by MIN/MAX optimization)
list.add(index);
// Normal index
list.add(index);
return list;
}
/**
* Calculate and get the start value of this range.
*
* @param session the session
* @return the start value
*/
public long getMin(SessionLocal session) {
optimize(session);
return min.getValue(session).getLong();
}
/**
* Calculate and get the end value of this range.
*
* @param session the session
* @return the end value
*/
public long getMax(SessionLocal session) {
optimize(session);
return max.getValue(session).getLong();
}
/**
* Get the increment.
*
* @param session the session
* @return the increment (1 by default)
*/
public long getStep(SessionLocal session) {
optimize(session);
if (step == null) {
return 1;
}
return step.getValue(session).getLong();
}
private void optimize(SessionLocal s) {
if (!optimized) {
min = min.optimize(s);
max = max.optimize(s);
if (step != null) {
step = step.optimize(s);
}
optimized = true;
}
}
@Override
public long getMaxDataModificationId() {
return 0;
}
@Override
public long getRowCountApproximation(SessionLocal session) {
return 100;
}
@Override
public boolean isDeterministic() {
return true;
}
}