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/*
* Copyright 2004-2022 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.expression.analysis;
import java.util.ArrayList;
import java.util.HashMap;
import org.h2.api.ErrorCode;
import org.h2.command.query.QueryOrderBy;
import org.h2.command.query.Select;
import org.h2.command.query.SelectGroups;
import org.h2.engine.SessionLocal;
import org.h2.expression.Expression;
import org.h2.expression.ExpressionVisitor;
import org.h2.message.DbException;
import org.h2.result.SortOrder;
import org.h2.table.ColumnResolver;
import org.h2.table.TableFilter;
import org.h2.value.Value;
import org.h2.value.ValueInteger;
/**
* A base class for data analysis operations such as aggregates and window
* functions.
*/
public abstract class DataAnalysisOperation extends Expression {
/**
* Reset stage. Used to reset internal data to its initial state.
*/
public static final int STAGE_RESET = 0;
/**
* Group stage, used for explicit or implicit GROUP BY operation.
*/
public static final int STAGE_GROUP = 1;
/**
* Window processing stage.
*/
public static final int STAGE_WINDOW = 2;
/**
* SELECT
*/
protected final Select select;
/**
* OVER clause
*/
protected Window over;
/**
* Sort order for OVER
*/
protected SortOrder overOrderBySort;
private int numFrameExpressions;
private int lastGroupRowId;
/**
* Create sort order.
*
* @param session
* database session
* @param orderBy
* array of order by expressions
* @param offset
* index offset
* @return the SortOrder
*/
protected static SortOrder createOrder(SessionLocal session, ArrayList orderBy, int offset) {
int size = orderBy.size();
int[] index = new int[size];
int[] sortType = new int[size];
for (int i = 0; i < size; i++) {
QueryOrderBy o = orderBy.get(i);
index[i] = i + offset;
sortType[i] = o.sortType;
}
return new SortOrder(session, index, sortType, null);
}
protected DataAnalysisOperation(Select select) {
this.select = select;
}
/**
* Sets the OVER condition.
*
* @param over
* OVER condition
*/
public void setOverCondition(Window over) {
this.over = over;
}
/**
* Checks whether this expression is an aggregate function.
*
* @return true if this is an aggregate function (including aggregates with
* OVER clause), false if this is a window function
*/
public abstract boolean isAggregate();
/**
* Returns the sort order for OVER clause.
*
* @return the sort order for OVER clause
*/
protected SortOrder getOverOrderBySort() {
return overOrderBySort;
}
@Override
public final void mapColumns(ColumnResolver resolver, int level, int state) {
if (over != null) {
if (state != MAP_INITIAL) {
throw DbException.get(ErrorCode.INVALID_USE_OF_AGGREGATE_FUNCTION_1, getTraceSQL());
}
state = MAP_IN_WINDOW;
} else {
if (state == MAP_IN_AGGREGATE) {
throw DbException.get(ErrorCode.INVALID_USE_OF_AGGREGATE_FUNCTION_1, getTraceSQL());
}
state = MAP_IN_AGGREGATE;
}
mapColumnsAnalysis(resolver, level, state);
}
/**
* Map the columns of the resolver to expression columns.
*
* @param resolver
* the column resolver
* @param level
* the subquery nesting level
* @param innerState
* one of the Expression MAP_IN_* values
*/
protected void mapColumnsAnalysis(ColumnResolver resolver, int level, int innerState) {
if (over != null) {
over.mapColumns(resolver, level);
}
}
@Override
public Expression optimize(SessionLocal session) {
if (over != null) {
over.optimize(session);
ArrayList orderBy = over.getOrderBy();
if (orderBy != null) {
overOrderBySort = createOrder(session, orderBy, getNumExpressions());
} else if (!isAggregate()) {
overOrderBySort = new SortOrder(session, new int[getNumExpressions()]);
}
WindowFrame frame = over.getWindowFrame();
if (frame != null) {
int index = getNumExpressions();
int orderBySize = 0;
if (orderBy != null) {
orderBySize = orderBy.size();
index += orderBySize;
}
int n = 0;
WindowFrameBound bound = frame.getStarting();
if (bound.isParameterized()) {
checkOrderBy(frame.getUnits(), orderBySize);
if (bound.isVariable()) {
bound.setExpressionIndex(index);
n++;
}
}
bound = frame.getFollowing();
if (bound != null && bound.isParameterized()) {
checkOrderBy(frame.getUnits(), orderBySize);
if (bound.isVariable()) {
bound.setExpressionIndex(index + n);
n++;
}
}
numFrameExpressions = n;
}
}
return this;
}
private void checkOrderBy(WindowFrameUnits units, int orderBySize) {
switch (units) {
case RANGE:
if (orderBySize != 1) {
String sql = getTraceSQL();
throw DbException.getSyntaxError(sql, sql.length() - 1,
"exactly one sort key is required for RANGE units");
}
break;
case GROUPS:
if (orderBySize < 1) {
String sql = getTraceSQL();
throw DbException.getSyntaxError(sql, sql.length() - 1,
"a sort key is required for GROUPS units");
}
break;
default:
}
}
@Override
public void setEvaluatable(TableFilter tableFilter, boolean b) {
if (over != null) {
over.setEvaluatable(tableFilter, b);
}
}
@Override
public final void updateAggregate(SessionLocal session, int stage) {
if (stage == STAGE_RESET) {
updateGroupAggregates(session, STAGE_RESET);
lastGroupRowId = 0;
return;
}
boolean window = stage == STAGE_WINDOW;
if (window != (over != null)) {
if (!window && select.isWindowQuery()) {
updateGroupAggregates(session, stage);
}
return;
}
SelectGroups groupData = select.getGroupDataIfCurrent(window);
if (groupData == null) {
// this is a different level (the enclosing query)
return;
}
int groupRowId = groupData.getCurrentGroupRowId();
if (lastGroupRowId == groupRowId) {
// already visited
return;
}
lastGroupRowId = groupRowId;
if (over != null) {
if (!select.isGroupQuery()) {
over.updateAggregate(session, stage);
}
}
updateAggregate(session, groupData, groupRowId);
}
/**
* Update a row of an aggregate.
*
* @param session
* the database session
* @param groupData
* data for the aggregate group
* @param groupRowId
* row id of group
*/
protected abstract void updateAggregate(SessionLocal session, SelectGroups groupData, int groupRowId);
/**
* Invoked when processing group stage of grouped window queries to update
* arguments of this aggregate.
*
* @param session
* the session
* @param stage
* select stage
*/
protected void updateGroupAggregates(SessionLocal session, int stage) {
if (over != null) {
over.updateAggregate(session, stage);
}
}
/**
* Returns the number of expressions, excluding OVER clause.
*
* @return the number of expressions
*/
protected abstract int getNumExpressions();
/**
* Returns the number of window frame expressions.
*
* @return the number of window frame expressions
*/
private int getNumFrameExpressions() {
return numFrameExpressions;
}
/**
* Stores current values of expressions into the specified array.
*
* @param session
* the session
* @param array
* array to store values of expressions
*/
protected abstract void rememberExpressions(SessionLocal session, Value[] array);
/**
* Get the aggregate data for a window clause.
*
* @param session
* database session
* @param groupData
* aggregate group data
* @param forOrderBy
* true if this is for ORDER BY
* @return the aggregate data object, specific to each kind of aggregate.
*/
protected Object getWindowData(SessionLocal session, SelectGroups groupData, boolean forOrderBy) {
Object data;
Value key = over.getCurrentKey(session);
PartitionData partition = groupData.getWindowExprData(this, key);
if (partition == null) {
data = forOrderBy ? new ArrayList<>() : createAggregateData();
groupData.setWindowExprData(this, key, new PartitionData(data));
} else {
data = partition.getData();
}
return data;
}
/**
* Get the aggregate group data object from the collector object.
*
* @param groupData
* the collector object
* @param ifExists
* if true, return null if object not found, if false, return new
* object if nothing found
* @return group data object
*/
protected Object getGroupData(SelectGroups groupData, boolean ifExists) {
Object data;
data = groupData.getCurrentGroupExprData(this);
if (data == null) {
if (ifExists) {
return null;
}
data = createAggregateData();
groupData.setCurrentGroupExprData(this, data);
}
return data;
}
/**
* Create aggregate data object specific to the subclass.
*
* @return aggregate-specific data object.
*/
protected abstract Object createAggregateData();
@Override
public boolean isEverything(ExpressionVisitor visitor) {
if (over == null) {
return true;
}
switch (visitor.getType()) {
case ExpressionVisitor.QUERY_COMPARABLE:
case ExpressionVisitor.OPTIMIZABLE_AGGREGATE:
case ExpressionVisitor.DETERMINISTIC:
case ExpressionVisitor.INDEPENDENT:
case ExpressionVisitor.DECREMENT_QUERY_LEVEL:
return false;
default:
return true;
}
}
@Override
public Value getValue(SessionLocal session) {
SelectGroups groupData = select.getGroupDataIfCurrent(over != null);
if (groupData == null) {
throw DbException.get(ErrorCode.INVALID_USE_OF_AGGREGATE_FUNCTION_1, getTraceSQL());
}
return over == null ? getAggregatedValue(session, getGroupData(groupData, true))
: getWindowResult(session, groupData);
}
/**
* Returns result of this window function or window aggregate. This method
* is not used for plain aggregates.
*
* @param session
* the session
* @param groupData
* the group data
* @return result of this function
*/
private Value getWindowResult(SessionLocal session, SelectGroups groupData) {
PartitionData partition;
Object data;
boolean isOrdered = over.isOrdered();
Value key = over.getCurrentKey(session);
partition = groupData.getWindowExprData(this, key);
if (partition == null) {
// Window aggregates with FILTER clause may have no collected values
data = isOrdered ? new ArrayList<>() : createAggregateData();
partition = new PartitionData(data);
groupData.setWindowExprData(this, key, partition);
} else {
data = partition.getData();
}
if (isOrdered || !isAggregate()) {
Value result = getOrderedResult(session, groupData, partition, data);
if (result == null) {
return getAggregatedValue(session, null);
}
return result;
}
// Window aggregate without ORDER BY clause in window specification
Value result = partition.getResult();
if (result == null) {
result = getAggregatedValue(session, data);
partition.setResult(result);
}
return result;
}
/***
* Returns aggregated value.
*
* @param session
* the session
* @param aggregateData
* the aggregate data
* @return aggregated value.
*/
protected abstract Value getAggregatedValue(SessionLocal session, Object aggregateData);
/**
* Update a row of an ordered aggregate.
*
* @param session
* the database session
* @param groupData
* data for the aggregate group
* @param groupRowId
* row id of group
* @param orderBy
* list of order by expressions
*/
protected void updateOrderedAggregate(SessionLocal session, SelectGroups groupData, int groupRowId,
ArrayList orderBy) {
int ne = getNumExpressions();
int size = orderBy != null ? orderBy.size() : 0;
int frameSize = getNumFrameExpressions();
Value[] array = new Value[ne + size + frameSize + 1];
rememberExpressions(session, array);
for (int i = 0; i < size; i++) {
@SuppressWarnings("null")
QueryOrderBy o = orderBy.get(i);
array[ne++] = o.expression.getValue(session);
}
if (frameSize > 0) {
WindowFrame frame = over.getWindowFrame();
WindowFrameBound bound = frame.getStarting();
if (bound.isVariable()) {
array[ne++] = bound.getValue().getValue(session);
}
bound = frame.getFollowing();
if (bound != null && bound.isVariable()) {
array[ne++] = bound.getValue().getValue(session);
}
}
array[ne] = ValueInteger.get(groupRowId);
@SuppressWarnings("unchecked")
ArrayList data = (ArrayList) getWindowData(session, groupData, true);
data.add(array);
}
private Value getOrderedResult(SessionLocal session, SelectGroups groupData, PartitionData partition, //
Object data) {
HashMap result = partition.getOrderedResult();
if (result == null) {
result = new HashMap<>();
@SuppressWarnings("unchecked")
ArrayList orderedData = (ArrayList) data;
int rowIdColumn = getNumExpressions();
ArrayList orderBy = over.getOrderBy();
if (orderBy != null) {
rowIdColumn += orderBy.size();
orderedData.sort(overOrderBySort);
}
rowIdColumn += getNumFrameExpressions();
getOrderedResultLoop(session, result, orderedData, rowIdColumn);
partition.setOrderedResult(result);
}
return result.get(groupData.getCurrentGroupRowId());
}
/**
* Returns result of this window function or window aggregate. This method
* may not be called on window aggregate without window order clause.
*
* @param session
* the session
* @param result
* the map to append result to
* @param ordered
* ordered data
* @param rowIdColumn
* the index of row id value
*/
protected abstract void getOrderedResultLoop(SessionLocal session, HashMap result,
ArrayList ordered, int rowIdColumn);
/**
* Used to create SQL for the OVER and FILTER clauses.
*
* @param builder
* string builder
* @param sqlFlags
* formatting flags
* @param forceOrderBy
* whether synthetic ORDER BY clause should be generated when it
* is missing
* @return the builder object
*/
protected StringBuilder appendTailConditions(StringBuilder builder, int sqlFlags, boolean forceOrderBy) {
if (over != null) {
builder.append(' ');
over.getSQL(builder, sqlFlags, forceOrderBy);
}
return builder;
}
}
