/*
* 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.constraint;
import java.util.ArrayList;
import java.util.HashSet;
import org.h2.engine.SessionLocal;
import org.h2.engine.NullsDistinct;
import org.h2.index.Index;
import org.h2.result.Row;
import org.h2.schema.Schema;
import org.h2.table.Column;
import org.h2.table.IndexColumn;
import org.h2.table.Table;
import org.h2.util.StringUtils;
/**
* A unique constraint. This object always backed by a unique index.
*/
public class ConstraintUnique extends Constraint {
private Index index;
private boolean indexOwner;
private IndexColumn[] columns;
private final boolean primaryKey;
private NullsDistinct nullsDistinct;
public ConstraintUnique(Schema schema, int id, String name, Table table, boolean primaryKey,
NullsDistinct nullsDistinct) {
super(schema, id, name, table);
this.primaryKey = primaryKey;
this.nullsDistinct = nullsDistinct;
}
@Override
public Type getConstraintType() {
return primaryKey ? Constraint.Type.PRIMARY_KEY : Constraint.Type.UNIQUE;
}
@Override
public String getCreateSQLForCopy(Table forTable, String quotedName) {
return getCreateSQLForCopy(forTable, quotedName, true);
}
private String getCreateSQLForCopy(Table forTable, String quotedName, boolean internalIndex) {
StringBuilder builder = new StringBuilder("ALTER TABLE ");
forTable.getSQL(builder, DEFAULT_SQL_FLAGS).append(" ADD CONSTRAINT ");
if (forTable.isHidden()) {
builder.append("IF NOT EXISTS ");
}
builder.append(quotedName);
if (comment != null) {
builder.append(" COMMENT ");
StringUtils.quoteStringSQL(builder, comment);
}
builder.append(' ').append(getConstraintType().getSqlName()).append('(');
IndexColumn.writeColumns(builder, columns, DEFAULT_SQL_FLAGS).append(')');
if (internalIndex && indexOwner && forTable == this.table) {
builder.append(" INDEX ");
index.getSQL(builder, DEFAULT_SQL_FLAGS);
}
return builder.toString();
}
@Override
public String getCreateSQLWithoutIndexes() {
return getCreateSQLForCopy(table, getSQL(DEFAULT_SQL_FLAGS), false);
}
@Override
public String getCreateSQL() {
return getCreateSQLForCopy(table, getSQL(DEFAULT_SQL_FLAGS));
}
public void setColumns(IndexColumn[] columns) {
this.columns = columns;
}
public IndexColumn[] getColumns() {
return columns;
}
/**
* Set the index to use for this unique constraint.
*
* @param index the index
* @param isOwner true if the index is generated by the system and belongs
* to this constraint
*/
public void setIndex(Index index, boolean isOwner) {
this.index = index;
this.indexOwner = isOwner;
}
@Override
public void removeChildrenAndResources(SessionLocal session) {
ArrayList<Constraint> constraints = table.getConstraints();
if (constraints != null) {
constraints = new ArrayList<>(table.getConstraints());
for (Constraint c : constraints) {
if (c.getReferencedConstraint() == this) {
database.removeSchemaObject(session, c);
}
}
}
table.removeConstraint(this);
if (indexOwner) {
table.removeIndexOrTransferOwnership(session, index);
}
database.removeMeta(session, getId());
index = null;
columns = null;
table = null;
invalidate();
}
@Override
public void checkRow(SessionLocal session, Table t, Row oldRow, Row newRow) {
// unique index check is enough
}
@Override
public boolean usesIndex(Index idx) {
return idx == index;
}
@Override
public void setIndexOwner(Index index) {
indexOwner = true;
}
@Override
public HashSet<Column> getReferencedColumns(Table table) {
HashSet<Column> result = new HashSet<>();
for (IndexColumn c : columns) {
result.add(c.column);
}
return result;
}
@Override
public boolean isBefore() {
return true;
}
@Override
public void checkExistingData(SessionLocal session) {
// no need to check: when creating the unique index any problems are
// found
}
@Override
public Index getIndex() {
return index;
}
@Override
public void rebuild() {
// nothing to do
}
/**
* @return are nulls distinct
*/
public NullsDistinct getNullsDistinct() {
return nullsDistinct;
}
}