Many resources are needed to download a project. Please understand that we have to compensate our server costs. Thank you in advance.
Project price only 1 $
You can buy this project and download/modify it how often you want.
org.h2.command.dml.Query Maven / Gradle / Ivy
/*
* Copyright 2004-2019 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.command.dml;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import org.h2.api.ErrorCode;
import org.h2.command.CommandInterface;
import org.h2.command.Prepared;
import org.h2.engine.Database;
import org.h2.engine.DbObject;
import org.h2.engine.Session;
import org.h2.expression.Alias;
import org.h2.expression.Expression;
import org.h2.expression.ExpressionColumn;
import org.h2.expression.ExpressionVisitor;
import org.h2.expression.Parameter;
import org.h2.expression.ValueExpression;
import org.h2.expression.function.FunctionCall;
import org.h2.message.DbException;
import org.h2.result.LocalResult;
import org.h2.result.ResultInterface;
import org.h2.result.ResultTarget;
import org.h2.result.SortOrder;
import org.h2.table.ColumnResolver;
import org.h2.table.Table;
import org.h2.table.TableFilter;
import org.h2.table.TableView;
import org.h2.util.StringUtils;
import org.h2.util.Utils;
import org.h2.value.Value;
import org.h2.value.ValueInt;
import org.h2.value.ValueNull;
/**
* Represents a SELECT statement (simple, or union).
*/
public abstract class Query extends Prepared {
/**
* Evaluated values of OFFSET and FETCH clauses.
*/
static final class OffsetFetch {
/**
* OFFSET value.
*/
final long offset;
/**
* FETCH value.
*/
final int fetch;
/**
* Whether FETCH value is a PERCENT value.
*/
final boolean fetchPercent;
OffsetFetch(long offset, int fetch, boolean fetchPercent) {
this.offset = offset;
this.fetch = fetch;
this.fetchPercent = fetchPercent;
}
}
/**
* The column list, including invisible expressions such as order by expressions.
*/
ArrayList expressions;
/**
* Array of expressions.
*
* @see #expressions
*/
Expression[] expressionArray;
/**
* Describes elements of the ORDER BY clause of a query.
*/
ArrayList orderList;
/**
* A sort order represents an ORDER BY clause in a query.
*/
SortOrder sort;
/**
* The limit expression as specified in the LIMIT or TOP clause.
*/
Expression limitExpr;
/**
* Whether limit expression specifies percentage of rows.
*/
boolean fetchPercent;
/**
* Whether tied rows should be included in result too.
*/
boolean withTies;
/**
* The offset expression as specified in the LIMIT .. OFFSET clause.
*/
Expression offsetExpr;
/**
* The sample size expression as specified in the SAMPLE_SIZE clause.
*/
Expression sampleSizeExpr;
/**
* Whether the result must only contain distinct rows.
*/
boolean distinct;
/**
* Whether the result needs to support random access.
*/
boolean randomAccessResult;
/**
* The visible columns (the ones required in the result).
*/
int visibleColumnCount;
/**
* Number of columns including visible columns and additional virtual
* columns for ORDER BY and DISTINCT ON clauses. This number does not
* include virtual columns for HAVING and QUALIFY.
*/
int resultColumnCount;
private boolean noCache;
private int lastLimit;
private long lastEvaluated;
private ResultInterface lastResult;
private Value[] lastParameters;
private boolean cacheableChecked;
private boolean neverLazy;
Query(Session session) {
super(session);
}
public void setNeverLazy(boolean b) {
this.neverLazy = b;
}
public boolean isNeverLazy() {
return neverLazy;
}
/**
* Check if this is a UNION query.
*
* @return {@code true} if this is a UNION query
*/
public abstract boolean isUnion();
/**
* Prepare join batching.
*/
public abstract void prepareJoinBatch();
@Override
public ResultInterface queryMeta() {
LocalResult result = session.getDatabase().getResultFactory().create(session, expressionArray,
visibleColumnCount, resultColumnCount);
result.done();
return result;
}
/**
* Execute the query without checking the cache. If a target is specified,
* the results are written to it, and the method returns null. If no target
* is specified, a new LocalResult is created and returned.
*
* @param limit the limit as specified in the JDBC method call
* @param target the target to write results to
* @return the result
*/
protected abstract ResultInterface queryWithoutCache(int limit,
ResultTarget target);
private ResultInterface queryWithoutCacheLazyCheck(int limit,
ResultTarget target) {
boolean disableLazy = neverLazy && session.isLazyQueryExecution();
if (disableLazy) {
session.setLazyQueryExecution(false);
}
try {
return queryWithoutCache(limit, target);
} finally {
if (disableLazy) {
session.setLazyQueryExecution(true);
}
}
}
/**
* Initialize the query.
*/
public abstract void init();
/**
* The the list of select expressions.
* This may include invisible expressions such as order by expressions.
*
* @return the list of expressions
*/
public ArrayList getExpressions() {
return expressions;
}
/**
* Calculate the cost to execute this query.
*
* @return the cost
*/
public abstract double getCost();
/**
* Calculate the cost when used as a subquery.
* This method returns a value between 10 and 1000000,
* to ensure adding other values can't result in an integer overflow.
*
* @return the estimated cost as an integer
*/
public int getCostAsExpression() {
// ensure the cost is not larger than 1 million,
// so that adding other values can't overflow
return (int) Math.min(1_000_000d, 10d + 10d * getCost());
}
/**
* Get all tables that are involved in this query.
*
* @return the set of tables
*/
public abstract HashSet getTables();
/**
* Set the order by list.
*
* @param order the order by list
*/
public void setOrder(ArrayList order) {
orderList = order;
}
/**
* Whether the query has an order.
*
* @return true if it has
*/
public boolean hasOrder() {
return orderList != null || sort != null;
}
/**
* Set the 'for update' flag.
*
* @param forUpdate the new setting
*/
public abstract void setForUpdate(boolean forUpdate);
/**
* Get the column count of this query.
*
* @return the column count
*/
public int getColumnCount() {
return visibleColumnCount;
}
/**
* Map the columns to the given column resolver.
*
* @param resolver
* the resolver
* @param level
* the subquery level (0 is the top level query, 1 is the first
* subquery level)
*/
public abstract void mapColumns(ColumnResolver resolver, int level);
/**
* Change the evaluatable flag. This is used when building the execution
* plan.
*
* @param tableFilter the table filter
* @param b the new value
*/
public abstract void setEvaluatable(TableFilter tableFilter, boolean b);
/**
* Add a condition to the query. This is used for views.
*
* @param param the parameter
* @param columnId the column index (0 meaning the first column)
* @param comparisonType the comparison type
*/
public abstract void addGlobalCondition(Parameter param, int columnId,
int comparisonType);
/**
* Check whether adding condition to the query is allowed. This is not
* allowed for views that have an order by and a limit, as it would affect
* the returned results.
*
* @return true if adding global conditions is allowed
*/
public abstract boolean allowGlobalConditions();
/**
* Check if this expression and all sub-expressions can fulfill a criteria.
* If any part returns false, the result is false.
*
* @param visitor the visitor
* @return if the criteria can be fulfilled
*/
public abstract boolean isEverything(ExpressionVisitor visitor);
@Override
public boolean isReadOnly() {
return isEverything(ExpressionVisitor.READONLY_VISITOR);
}
/**
* Update all aggregate function values.
*
* @param s the session
* @param stage select stage
*/
public abstract void updateAggregate(Session s, int stage);
/**
* Call the before triggers on all tables.
*/
public abstract void fireBeforeSelectTriggers();
/**
* Set the distinct flag only if it is possible, may be used as a possible
* optimization only.
*/
public void setDistinctIfPossible() {
if (!isAnyDistinct() && offsetExpr == null && limitExpr == null) {
distinct = true;
}
}
/**
* @return whether this query is a plain {@code DISTINCT} query
*/
public boolean isStandardDistinct() {
return distinct;
}
/**
* @return whether this query is a {@code DISTINCT} or
* {@code DISTINCT ON (...)} query
*/
public boolean isAnyDistinct() {
return distinct;
}
/**
* Returns whether results support random access.
*
* @return whether results support random access
*/
public boolean isRandomAccessResult() {
return randomAccessResult;
}
/**
* Whether results need to support random access.
*
* @param b the new value
*/
public void setRandomAccessResult(boolean b) {
randomAccessResult = b;
}
@Override
public boolean isQuery() {
return true;
}
@Override
public boolean isTransactional() {
return true;
}
/**
* Disable caching of result sets.
*/
public void disableCache() {
this.noCache = true;
}
private boolean sameResultAsLast(Session s, Value[] params,
Value[] lastParams, long lastEval) {
if (!cacheableChecked) {
long max = getMaxDataModificationId();
noCache = max == Long.MAX_VALUE;
if (!isEverything(ExpressionVisitor.DETERMINISTIC_VISITOR) ||
!isEverything(ExpressionVisitor.INDEPENDENT_VISITOR)) {
noCache = true;
}
cacheableChecked = true;
}
if (noCache) {
return false;
}
Database db = s.getDatabase();
for (int i = 0; i < params.length; i++) {
Value a = lastParams[i], b = params[i];
if (a.getValueType() != b.getValueType() || !db.areEqual(a, b)) {
return false;
}
}
return getMaxDataModificationId() <= lastEval;
}
private Value[] getParameterValues() {
ArrayList list = getParameters();
if (list == null) {
return new Value[0];
}
int size = list.size();
Value[] params = new Value[size];
for (int i = 0; i < size; i++) {
Value v = list.get(i).getParamValue();
params[i] = v;
}
return params;
}
@Override
public final ResultInterface query(int maxrows) {
return query(maxrows, null);
}
/**
* Execute the query, writing the result to the target result.
*
* @param limit the maximum number of rows to return
* @param target the target result (null will return the result)
* @return the result set (if the target is not set).
*/
public final ResultInterface query(int limit, ResultTarget target) {
if (isUnion()) {
// union doesn't always know the parameter list of the left and
// right queries
return queryWithoutCacheLazyCheck(limit, target);
}
fireBeforeSelectTriggers();
if (noCache || !session.getDatabase().getOptimizeReuseResults() ||
(session.isLazyQueryExecution() && !neverLazy)) {
return queryWithoutCacheLazyCheck(limit, target);
}
Value[] params = getParameterValues();
long now = session.getDatabase().getModificationDataId();
if (isEverything(ExpressionVisitor.DETERMINISTIC_VISITOR)) {
if (lastResult != null && !lastResult.isClosed() &&
limit == lastLimit) {
if (sameResultAsLast(session, params, lastParameters,
lastEvaluated)) {
lastResult = lastResult.createShallowCopy(session);
if (lastResult != null) {
lastResult.reset();
return lastResult;
}
}
}
}
lastParameters = params;
closeLastResult();
ResultInterface r = queryWithoutCacheLazyCheck(limit, target);
lastResult = r;
this.lastEvaluated = now;
lastLimit = limit;
return r;
}
private void closeLastResult() {
if (lastResult != null) {
lastResult.close();
}
}
/**
* Initialize the order by list. This call may extend the expressions list.
*
* @param session the session
* @param expressions the select list expressions
* @param expressionSQL the select list SQL snippets
* @param orderList the order by list
* @param visible the number of visible columns in the select list
* @param mustBeInResult all order by expressions must be in the select list
* @param filters the table filters
*/
static void initOrder(Session session,
ArrayList expressions,
ArrayList expressionSQL,
List orderList,
int visible,
boolean mustBeInResult,
ArrayList filters) {
for (SelectOrderBy o : orderList) {
Expression e = o.expression;
if (e == null) {
continue;
}
int idx = initExpression(session, expressions, expressionSQL, e, visible, mustBeInResult, filters);
o.columnIndexExpr = ValueExpression.get(ValueInt.get(idx + 1));
o.expression = expressions.get(idx).getNonAliasExpression();
}
}
/**
* Initialize the 'ORDER BY' or 'DISTINCT' expressions.
*
* @param session the session
* @param expressions the select list expressions
* @param expressionSQL the select list SQL snippets
* @param e the expression.
* @param visible the number of visible columns in the select list
* @param mustBeInResult all order by expressions must be in the select list
* @param filters the table filters.
* @return index on the expression in the {@link #expressions} list.
*/
static int initExpression(Session session, ArrayList expressions,
ArrayList expressionSQL, Expression e, int visible, boolean mustBeInResult,
ArrayList filters) {
Database db = session.getDatabase();
// special case: SELECT 1 AS A FROM DUAL ORDER BY A
// (oracle supports it, but only in order by, not in group by and
// not in having):
// SELECT 1 AS A FROM DUAL ORDER BY -A
if (e instanceof ExpressionColumn) {
// order by expression
ExpressionColumn exprCol = (ExpressionColumn) e;
String tableAlias = exprCol.getOriginalTableAliasName();
String col = exprCol.getOriginalColumnName();
for (int j = 0; j < visible; j++) {
Expression ec = expressions.get(j);
if (ec instanceof ExpressionColumn) {
// select expression
ExpressionColumn c = (ExpressionColumn) ec;
if (!db.equalsIdentifiers(col, c.getColumnName())) {
continue;
}
if (tableAlias == null) {
return j;
}
String ca = c.getOriginalTableAliasName();
if (ca != null) {
if (db.equalsIdentifiers(ca, tableAlias)) {
return j;
}
} else if (filters != null) {
// select id from test order by test.id
for (TableFilter f : filters) {
if (db.equalsIdentifiers(f.getTableAlias(), tableAlias)) {
return j;
}
}
}
} else if (ec instanceof Alias) {
if (tableAlias == null && db.equalsIdentifiers(col, ec.getAlias())) {
return j;
}
Expression ec2 = ec.getNonAliasExpression();
if (ec2 instanceof ExpressionColumn) {
ExpressionColumn c2 = (ExpressionColumn) ec2;
String ta = exprCol.getSQL(true);
String tb = c2.getSQL(true);
String s2 = c2.getColumnName();
if (db.equalsIdentifiers(col, s2) && db.equalsIdentifiers(ta, tb)) {
return j;
}
}
}
}
} else if (expressionSQL != null) {
String s = e.getSQL(true);
for (int j = 0, size = expressionSQL.size(); j < size; j++) {
if (db.equalsIdentifiers(expressionSQL.get(j), s)) {
return j;
}
}
}
if (expressionSQL == null
|| mustBeInResult && !db.getMode().allowUnrelatedOrderByExpressionsInDistinctQueries
&& !checkOrderOther(session, e, expressionSQL)) {
throw DbException.get(ErrorCode.ORDER_BY_NOT_IN_RESULT, e.getSQL(false));
}
int idx = expressions.size();
expressions.add(e);
expressionSQL.add(e.getSQL(true));
return idx;
}
/**
* An additional check for expression in ORDER BY list for DISTINCT selects
* that was not matched with selected expressions in regular way. This
* method allows expressions based only on selected expressions in different
* complicated ways with functions, comparisons, or operators.
*
* @param session session
* @param expr expression to check
* @param expressionSQL SQL of allowed expressions
* @return whether the specified expression should be allowed in ORDER BY
* list of DISTINCT select
*/
private static boolean checkOrderOther(Session session, Expression expr, ArrayList expressionSQL) {
if (expr == null || expr.isConstant()) {
// ValueExpression, null expression in CASE, or other
return true;
}
String exprSQL = expr.getSQL(true);
for (String sql: expressionSQL) {
if (session.getDatabase().equalsIdentifiers(exprSQL, sql)) {
return true;
}
}
int count = expr.getSubexpressionCount();
if (expr instanceof FunctionCall) {
if (!((FunctionCall) expr).isDeterministic()) {
return false;
}
} else if (count <= 0) {
// Expression is an ExpressionColumn, Parameter, SequenceValue or
// has other unsupported type without subexpressions
return false;
}
for (int i = 0; i < count; i++) {
if (!checkOrderOther(session, expr.getSubexpression(i), expressionSQL)) {
return false;
}
}
return true;
}
/**
* Create a {@link SortOrder} object given the list of {@link SelectOrderBy}
* objects.
*
* @param orderList a list of {@link SelectOrderBy} elements
* @param expressionCount the number of columns in the query
* @return the {@link SortOrder} object
*/
public SortOrder prepareOrder(ArrayList orderList, int expressionCount) {
int size = orderList.size();
int[] index = new int[size];
int[] sortType = new int[size];
for (int i = 0; i < size; i++) {
SelectOrderBy o = orderList.get(i);
int idx;
boolean reverse = false;
Value v = o.columnIndexExpr.getValue(null);
if (v == ValueNull.INSTANCE) {
// parameter not yet set - order by first column
idx = 0;
} else {
idx = v.getInt();
if (idx < 0) {
reverse = true;
idx = -idx;
}
idx -= 1;
if (idx < 0 || idx >= expressionCount) {
throw DbException.get(ErrorCode.ORDER_BY_NOT_IN_RESULT, Integer.toString(idx + 1));
}
}
index[i] = idx;
int type = o.sortType;
if (reverse) {
// TODO NULLS FIRST / LAST should be inverted too?
type ^= SortOrder.DESCENDING;
}
sortType[i] = type;
}
return new SortOrder(session.getDatabase(), index, sortType, orderList);
}
@Override
public int getType() {
return CommandInterface.SELECT;
}
public void setOffset(Expression offset) {
this.offsetExpr = offset;
}
public Expression getOffset() {
return offsetExpr;
}
public void setLimit(Expression limit) {
this.limitExpr = limit;
}
public Expression getLimit() {
return limitExpr;
}
public void setFetchPercent(boolean fetchPercent) {
this.fetchPercent = fetchPercent;
}
public boolean isFetchPercent() {
return fetchPercent;
}
public void setWithTies(boolean withTies) {
this.withTies = withTies;
}
public boolean isWithTies() {
return withTies;
}
/**
* Add a parameter to the parameter list.
*
* @param param the parameter to add
*/
void addParameter(Parameter param) {
if (parameters == null) {
parameters = Utils.newSmallArrayList();
}
parameters.add(param);
}
public void setSampleSize(Expression sampleSize) {
this.sampleSizeExpr = sampleSize;
}
/**
* 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();
}
public final long getMaxDataModificationId() {
ExpressionVisitor visitor = ExpressionVisitor.getMaxModificationIdVisitor();
isEverything(visitor);
return Math.max(visitor.getMaxDataModificationId(), session.getSnapshotDataModificationId());
}
/**
* Appends ORDER BY, OFFSET, and FETCH clauses to the plan.
*
* @param builder query plan string builder.
* @param alwaysQuote quote all identifiers
* @param expressions the array of expressions
*/
void appendEndOfQueryToSQL(StringBuilder builder, boolean alwaysQuote, Expression[] expressions) {
if (sort != null) {
builder.append("\nORDER BY ").append(sort.getSQL(expressions, visibleColumnCount, alwaysQuote));
} else if (orderList != null) {
builder.append("\nORDER BY ");
for (int i = 0, l = orderList.size(); i < l; i++) {
if (i > 0) {
builder.append(", ");
}
orderList.get(i).getSQL(builder, alwaysQuote);
}
}
if (offsetExpr != null) {
String count = StringUtils.unEnclose(offsetExpr.getSQL(alwaysQuote));
builder.append("\nOFFSET ").append(count).append("1".equals(count) ? " ROW" : " ROWS");
}
if (limitExpr != null) {
builder.append("\nFETCH ").append(offsetExpr != null ? "NEXT" : "FIRST");
String count = StringUtils.unEnclose(limitExpr.getSQL(alwaysQuote));
boolean withCount = fetchPercent || !"1".equals(count);
if (withCount) {
builder.append(' ').append(count);
if (fetchPercent) {
builder.append(" PERCENT");
}
}
builder.append(!withCount ? " ROW" : " ROWS")
.append(withTies ? " WITH TIES" : " ONLY");
}
}
/**
* Evaluates OFFSET and FETCH expressions.
*
* @param maxRows
* additional limit
* @return the evaluated values
*/
OffsetFetch getOffsetFetch(int maxRows) {
int fetch = maxRows == 0 ? -1 : maxRows;
if (limitExpr != null) {
Value v = limitExpr.getValue(session);
int l = v == ValueNull.INSTANCE ? -1 : v.getInt();
if (fetch < 0) {
fetch = l;
} else if (l >= 0) {
fetch = Math.min(l, fetch);
}
}
boolean fetchPercent = this.fetchPercent;
if (fetchPercent) {
// Need to check it now, because negative limit has special treatment later
if (fetch < 0 || fetch > 100) {
throw DbException.getInvalidValueException("FETCH PERCENT", fetch);
}
// 0 PERCENT means 0
if (fetch == 0) {
fetchPercent = false;
}
}
long offset;
if (offsetExpr != null) {
offset = offsetExpr.getValue(session).getLong();
if (offset < 0) {
offset = 0;
}
} else {
offset = 0;
}
return new OffsetFetch(offset, fetch, fetchPercent);
}
/**
* Applies limits, if any, to a result and makes it ready for value
* retrieval.
*
* @param result
* the result
* @param offset
* OFFSET value
* @param fetch
* FETCH value
* @param fetchPercent
* whether FETCH value is a PERCENT value
* @param target
* target result or null
* @return the result or null
*/
LocalResult finishResult(LocalResult result, long offset, int fetch, boolean fetchPercent, ResultTarget target) {
if (offset != 0) {
if (offset > Integer.MAX_VALUE) {
throw DbException.getInvalidValueException("OFFSET", offset);
}
result.setOffset((int) offset);
}
if (fetch >= 0) {
result.setLimit(fetch);
result.setFetchPercent(fetchPercent);
if (withTies) {
result.setWithTies(sort);
}
}
result.done();
if (randomAccessResult && !distinct) {
result = convertToDistinct(result);
}
if (target != null) {
while (result.next()) {
target.addRow(result.currentRow());
}
result.close();
return null;
}
return result;
}
/**
* Convert a result into a distinct result, using the current columns.
*
* @param result the source
* @return the distinct result
*/
LocalResult convertToDistinct(ResultInterface result) {
LocalResult distinctResult = session.getDatabase().getResultFactory().create(session,
expressionArray, visibleColumnCount, resultColumnCount);
distinctResult.setDistinct();
result.reset();
while (result.next()) {
distinctResult.addRow(result.currentRow());
}
result.close();
distinctResult.done();
return distinctResult;
}
/**
* Converts this query to a table or a view.
*
* @param alias alias name for the view
* @param parameters the parameters
* @param forCreateView if true, a system session will be used for the view
* @param topQuery the top level query
* @return the table or the view
*/
public Table toTable(String alias, ArrayList parameters, boolean forCreateView, Query topQuery) {
setParameterList(new ArrayList<>(parameters));
init();
return TableView.createTempView(forCreateView ? session.getDatabase().getSystemSession() : session,
session.getUser(), alias, this, topQuery);
}
@Override
public void collectDependencies(HashSet dependencies) {
ExpressionVisitor visitor = ExpressionVisitor.getDependenciesVisitor(dependencies);
isEverything(visitor);
}
}
