private void optimize(Session s) {
if (!optimized) {
min = min.optimize(s);
max = max.optimize(s);
if (step != null) {
step = step.optimize(s);
}
optimized = true;
}
}
private void setEvaluatableRecursive(TableFilter f) {
for (; f != null; f = f.getJoin()) {
f.setEvaluatable(f, true);
if (condition != null) {
condition.setEvaluatable(f, true);
}
TableFilter n = f.getNestedJoin();
if (n != null) {
setEvaluatableRecursive(n);
}
Expression on = f.getJoinCondition();
if (on != null) {
if (!on.isEverything(ExpressionVisitor.EVALUATABLE_VISITOR)) {
if (session.getDatabase().getSettings().nestedJoins) {
// need to check that all added are bound to a table
on = on.optimize(session);
if (!f.isJoinOuter() && !f.isJoinOuterIndirect()) {
f.removeJoinCondition();
addCondition(on);
}
} else {
if (f.isJoinOuter()) {
// this will check if all columns exist - it may or may not throw an exception
on = on.optimize(session);
// it is not supported even if the columns exist
throw DbException.get(ErrorCode.UNSUPPORTED_OUTER_JOIN_CONDITION_1, on.getSQL());
}
f.removeJoinCondition();
// need to check that all added are bound to a table
on = on.optimize(session);
addCondition(on);
}
}
}
on = f.getFilterCondition();
if (on != null) {
if (!on.isEverything(ExpressionVisitor.EVALUATABLE_VISITOR)) {
f.removeFilterCondition();
addCondition(on);
}
}
// this is only important for subqueries, so they know
// the result columns are evaluatable
for (Expression e : expressions) {
e.setEvaluatable(f, true);
}
}
}
@Override
public void prepare() {
if (columns == null) {
// 如INSERT INTO InsertTest DEFAULT VALUES
if (list.size() > 0 && list.get(0).length == 0) {
// special case where table is used as a sequence
columns = new Column[0];
} else { // 如INSERT INTO InsertTest(SELECT * FROM tmpSelectTest)
columns = table.getColumns();
}
}
if (list.size() > 0) {
for (Expression[] expr : list) {
if (expr.length != columns.length) {
throw DbException.get(ErrorCode.COLUMN_COUNT_DOES_NOT_MATCH);
}
for (int i = 0, len = expr.length; i < len; i++) {
Expression e = expr[i];
if (e != null) {
e = e.optimize(session);
if (e instanceof Parameter) {
Parameter p = (Parameter) e;
p.setColumn(columns[i]);
}
expr[i] = e;
}
}
}
} else {
query.prepare();
if (query.getColumnCount() != columns.length) {
throw DbException.get(ErrorCode.COLUMN_COUNT_DOES_NOT_MATCH);
}
}
}
private int insertRows() {
session.getUser().checkRight(table, Right.INSERT);
setCurrentRowNumber(0);
table.fire(session, Trigger.INSERT, true);
rowNumber = 0;
int listSize = list.size();
if (listSize > 0) {
int columnLen = columns.length;
for (int x = 0; x < listSize; x++) {
Row newRow = table.getTemplateRow(); // newRow的长度是全表字段的个数是，会>=columns的长度
Expression[] expr = list.get(x);
setCurrentRowNumber(x + 1);
for (int i = 0; i < columnLen; i++) {
Column c = columns[i];
int index = c.getColumnId(); // 从0开始
Expression e = expr[i];
if (e != null) {
// e can be null (DEFAULT)
e = e.optimize(session);
try {
Value v = c.convert(e.getValue(session));
newRow.setValue(index, v);
} catch (DbException ex) {
throw setRow(ex, x, getSQL(expr));
}
}
}
rowNumber++;
table.validateConvertUpdateSequence(session, newRow);
boolean done = table.fireBeforeRow(session, null, newRow); // INSTEAD OF触发器会返回true
if (!done) {
// 直到事务commit或rollback时才解琐，见org.h2.engine.Session.unlockAll()
table.lock(session, true, false);
table.addRow(session, newRow);
// 在org.h2.index.PageDataIndex.addTry(Session, Row)中事先记了一次PageLog
// 也就是org.h2.store.PageStore.logAddOrRemoveRow(Session, int, Row, boolean)
// 这里又记了一次UndoLog
// UndoLog在org.h2.engine.Session.commit(boolean)时就清除了
session.log(table, UndoLogRecord.INSERT, newRow);
table.fireAfterRow(session, null, newRow, false);
}
}
} else {
table.lock(session, true, false);
// 这种方式主要是避免循环两次，因为query内部己循环一次了，得到记录后像else中的非insertFromSelect一样，还要循环一次
if (insertFromSelect) {
query.query(0, this); // 每遍历一行会回调下面的addRow方法
} else {
ResultInterface rows = query.query(0);
while (rows.next()) {
Value[] r = rows.currentRow();
addRow(r);
}
rows.close();
}
}
table.fire(session, Trigger.INSERT, false);
return rowNumber;
}
/**
* Get the sample size, if set.
*
* @param session the session
* @return the sample size
*/
int getSampleSizeValue(Session session) {
if (sampleSizeExpr == null) {
return 0;
}
Value v = sampleSizeExpr.optimize(session).getValue(session);
if (v == ValueNull.INSTANCE) {
return 0;
}
return v.getInt();
}
// limitExpr在org.h2.command.Parser.parseDelete()中调用过optimize了，所以在这里不用再调用
// 因为limitExpr不会涉及到列，所以也不需要调用mapColumns
@Override
public void prepare() {
if (condition != null) {
condition.mapColumns(tableFilter, 0);
condition = condition.optimize(session);
condition.createIndexConditions(session, tableFilter);
}
// 为什么不能像mapColumns把level设为0，因为getBestPlanItem内部会把level当被除数，所以不行。
PlanItem item = tableFilter.getBestPlanItem(session, 1);
tableFilter.setPlanItem(item);
tableFilter.prepare();
}
public int update() throws SQLException {
session.commit(true);
session.getUser().checkAdmin();
Database db = session.getDatabase();
if (getSchema().findConstant(constantName) != null) {
if (ifNotExists) {
return 0;
}
throw Message.getSQLException(ErrorCode.CONSTANT_ALREADY_EXISTS_1, constantName);
}
int id = getObjectId(false, true);
Constant constant = new Constant(getSchema(), id, constantName);
expression = expression.optimize(session);
Value value = expression.getValue(session);
constant.setValue(value);
db.addSchemaObject(session, constant);
return 0;
}
public void addGlobalCondition(Parameter param, int columnId, int comparisonType) {
addParameter(param);
Expression comp;
Expression col = expressions.get(columnId);
col = col.getNonAliasExpression();
if (col.isEverything(ExpressionVisitor.QUERY_COMPARABLE_VISITOR)) {
comp = new Comparison(session, comparisonType, col, param);
} else {
// this condition will always evaluate to true, but need to
// add the parameter, so it can be set later
comp = new Comparison(session, Comparison.EQUAL_NULL_SAFE, param, param);
}
comp = comp.optimize(session);
boolean addToCondition = true;
if (isGroupQuery) {
addToCondition = false;
for (int i = 0; groupIndex != null && i < groupIndex.length; i++) {
if (groupIndex[i] == columnId) {
addToCondition = true;
break;
}
}
if (!addToCondition) {
if (havingIndex >= 0) {
having = expressions.get(havingIndex);
}
if (having == null) {
having = comp;
} else {
having = new ConditionAndOr(ConditionAndOr.AND, having, comp);
}
}
}
if (addToCondition) {
if (condition == null) {
condition = comp;
} else {
condition = new ConditionAndOr(ConditionAndOr.AND, condition, comp);
}
}
}
private byte[] getByteArray(Expression e) {
return StringUtils.convertHexToBytes(e.optimize(session).getValue(session).getString());
}
private char[] getCharArray(Expression e) {
return e.optimize(session).getValue(session).getString().toCharArray();
}
public void prepare() {
if (isPrepared) {
// sometimes a subquery is prepared twice (CREATE TABLE AS SELECT)
return;
}
if (SysProperties.CHECK && !checkInit) {
DbException.throwInternalError("not initialized");
}
if (orderList != null) {
sort = prepareOrder(orderList, expressions.size());
orderList = null;
}
for (int i = 0; i < expressions.size(); i++) {
Expression e = expressions.get(i);
expressions.set(i, e.optimize(session));
}
if (condition != null) {
condition = condition.optimize(session);
for (TableFilter f : filters) {
// outer joins: must not add index conditions such as
// "c is null" - example:
// create table parent(p int primary key) as select 1;
// create table child(c int primary key, pc int);
// insert into child values(2, 1);
// select p, c from parent
// left outer join child on p = pc where c is null;
if (!f.isJoinOuter() && !f.isJoinOuterIndirect()) {
condition.createIndexConditions(session, f);
}
}
}
if (isGroupQuery && groupIndex == null && havingIndex < 0 && filters.size() == 1) {
if (condition == null) {
Table t = filters.get(0).getTable();
ExpressionVisitor optimizable = ExpressionVisitor.getOptimizableVisitor(t);
isQuickAggregateQuery = isEverything(optimizable);
}
}
cost = preparePlan();
if (distinct
&& session.getDatabase().getSettings().optimizeDistinct
&& !isGroupQuery
&& filters.size() == 1
&& expressions.size() == 1
&& condition == null) {
Expression expr = expressions.get(0);
expr = expr.getNonAliasExpression();
if (expr instanceof ExpressionColumn) {
Column column = ((ExpressionColumn) expr).getColumn();
int selectivity = column.getSelectivity();
Index columnIndex = topTableFilter.getTable().getIndexForColumn(column);
if (columnIndex != null
&& selectivity != Constants.SELECTIVITY_DEFAULT
&& selectivity < 20) {
// the first column must be ascending
boolean ascending = columnIndex.getIndexColumns()[0].sortType == SortOrder.ASCENDING;
Index current = topTableFilter.getIndex();
// if another index is faster
if (columnIndex.canFindNext()
&& ascending
&& (current == null || current.getIndexType().isScan() || columnIndex == current)) {
IndexType type = columnIndex.getIndexType();
// hash indexes don't work, and unique single column indexes don't work
if (!type.isHash() && (!type.isUnique() || columnIndex.getColumns().length > 1)) {
topTableFilter.setIndex(columnIndex);
isDistinctQuery = true;
}
}
}
}
}
if (sort != null && !isQuickAggregateQuery && !isGroupQuery) {
Index index = getSortIndex();
if (index != null) {
Index current = topTableFilter.getIndex();
if (current.getIndexType().isScan() || current == index) {
topTableFilter.setIndex(index);
if (!topTableFilter.hasInComparisons()) {
// in(select ...) and in(1,2,3) my return the key in another order
sortUsingIndex = true;
}
} else if (index.getIndexColumns().length >= current.getIndexColumns().length) {
IndexColumn[] sortColumns = index.getIndexColumns();
IndexColumn[] currentColumns = current.getIndexColumns();
boolean swapIndex = false;
for (int i = 0; i < currentColumns.length; i++) {
if (sortColumns[i].column != currentColumns[i].column) {
swapIndex = false;
break;
}
if (sortColumns[i].sortType != currentColumns[i].sortType) {
swapIndex = true;
}
}
if (swapIndex) {
topTableFilter.setIndex(index);
sortUsingIndex = true;
}
}
}
}
if (!isQuickAggregateQuery && isGroupQuery && getGroupByExpressionCount() > 0) {
Index index = getGroupSortedIndex();
Index current = topTableFilter.getIndex();
if (index != null && (current.getIndexType().isScan() || current == index)) {
topTableFilter.setIndex(index);
isGroupSortedQuery = true;
}
}
expressionArray = new Expression[expressions.size()];
expressions.toArray(expressionArray);
isPrepared = true;
}
@Override
public int update() {
session.commit(true);
Database db = session.getDatabase();
session.getUser().checkRight(table, Right.ALL);
table.checkSupportAlter();
table.lock(session, true, true);
if (newColumn != null) {
checkDefaultReferencesTable(newColumn.getDefaultExpression());
}
if (columnsToAdd != null) {
for (Column column : columnsToAdd) {
checkDefaultReferencesTable(column.getDefaultExpression());
}
}
switch (type) {
case CommandInterface.ALTER_TABLE_ALTER_COLUMN_NOT_NULL:
{
if (!oldColumn.isNullable()) {
// no change
break;
}
checkNoNullValues();
oldColumn.setNullable(false);
db.updateMeta(session, table);
break;
}
case CommandInterface.ALTER_TABLE_ALTER_COLUMN_NULL:
{
if (oldColumn.isNullable()) {
// no change
break;
}
checkNullable();
oldColumn.setNullable(true);
db.updateMeta(session, table);
break;
}
case CommandInterface.ALTER_TABLE_ALTER_COLUMN_DEFAULT:
{
Sequence sequence = oldColumn == null ? null : oldColumn.getSequence();
checkDefaultReferencesTable(defaultExpression);
oldColumn.setSequence(null);
oldColumn.setDefaultExpression(session, defaultExpression);
removeSequence(sequence);
db.updateMeta(session, table);
break;
}
case CommandInterface.ALTER_TABLE_ALTER_COLUMN_CHANGE_TYPE:
{
// if the change is only increasing the precision, then we don't
// need to copy the table because the length is only a constraint,
// and does not affect the storage structure.
if (oldColumn.isWideningConversion(newColumn)) {
convertAutoIncrementColumn(newColumn);
oldColumn.copy(newColumn);
db.updateMeta(session, table);
} else {
oldColumn.setSequence(null);
oldColumn.setDefaultExpression(session, null);
oldColumn.setConvertNullToDefault(false);
if (oldColumn.isNullable() && !newColumn.isNullable()) {
checkNoNullValues();
} else if (!oldColumn.isNullable() && newColumn.isNullable()) {
checkNullable();
}
convertAutoIncrementColumn(newColumn);
copyData();
}
break;
}
case CommandInterface.ALTER_TABLE_ADD_COLUMN:
{
// ifNotExists only supported for single column add
if (ifNotExists
&& columnsToAdd.size() == 1
&& table.doesColumnExist(columnsToAdd.get(0).getName())) {
break;
}
for (Column column : columnsToAdd) {
if (column.isAutoIncrement()) {
int objId = getObjectId();
column.convertAutoIncrementToSequence(
session, getSchema(), objId, table.isTemporary());
}
}
copyData();
break;
}
case CommandInterface.ALTER_TABLE_DROP_COLUMN:
{
if (table.getColumns().length - columnsToRemove.size() < 1) {
throw DbException.get(
ErrorCode.CANNOT_DROP_LAST_COLUMN, columnsToRemove.get(0).getSQL());
}
table.dropMultipleColumnsConstraintsAndIndexes(session, columnsToRemove);
copyData();
break;
}
case CommandInterface.ALTER_TABLE_ALTER_COLUMN_SELECTIVITY:
{
int value = newSelectivity.optimize(session).getValue(session).getInt();
oldColumn.setSelectivity(value);
db.updateMeta(session, table);
break;
}
default:
DbException.throwInternalError("type=" + type);
}
return 0;
}