SelectListColumnResolver(Select select) {
this.select = select;
int columnCount = select.getColumnCount();
columns = new Column[columnCount];
expressions = new Expression[columnCount];
ArrayList<Expression> columnList = select.getExpressions();
for (int i = 0; i < columnCount; i++) {
Expression expr = columnList.get(i);
Column column = new Column(expr.getAlias(), Value.NULL);
column.setTable(null, i);
columns[i] = column;
expressions[i] = expr.getNonAliasExpression();
}
}
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);
}
}
}
/**
* 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<Expression> expressions,
ArrayList<String> expressionSQL,
ArrayList<SelectOrderBy> orderList,
int visible,
boolean mustBeInResult,
ArrayList<TableFilter> filters) {
Database db = session.getDatabase();
for (SelectOrderBy o : orderList) {
Expression e = o.expression;
if (e == null) {
continue;
}
// 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
boolean isAlias = false;
int idx = expressions.size();
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++) {
boolean found = false;
Expression ec = expressions.get(j);
if (ec instanceof ExpressionColumn) {
// select expression
ExpressionColumn c = (ExpressionColumn) ec;
found = db.equalsIdentifiers(col, c.getColumnName());
if (found && tableAlias != null) {
String ca = c.getOriginalTableAliasName();
if (ca == null) {
found = false;
if (filters != null) {
// select id from test order by test.id
for (int i = 0, size = filters.size(); i < size; i++) {
TableFilter f = filters.get(i);
if (db.equalsIdentifiers(f.getTableAlias(), tableAlias)) {
found = true;
break;
}
}
}
} else {
found = db.equalsIdentifiers(ca, tableAlias);
}
}
} else if (!(ec instanceof Alias)) {
continue;
} else if (tableAlias == null && db.equalsIdentifiers(col, ec.getAlias())) {
found = true;
} else {
Expression ec2 = ec.getNonAliasExpression();
if (ec2 instanceof ExpressionColumn) {
ExpressionColumn c2 = (ExpressionColumn) ec2;
String ta = exprCol.getSQL();
String tb = c2.getSQL();
String s2 = c2.getColumnName();
found = db.equalsIdentifiers(col, s2);
if (!db.equalsIdentifiers(ta, tb)) {
found = false;
}
}
}
if (found) {
idx = j;
isAlias = true;
break;
}
}
} else {
String s = e.getSQL();
if (expressionSQL != null) {
for (int j = 0, size = expressionSQL.size(); j < size; j++) {
String s2 = expressionSQL.get(j);
if (db.equalsIdentifiers(s2, s)) {
idx = j;
isAlias = true;
break;
}
}
}
}
if (!isAlias) {
if (mustBeInResult) {
throw DbException.get(ErrorCode.ORDER_BY_NOT_IN_RESULT, e.getSQL());
}
expressions.add(e);
String sql = e.getSQL();
expressionSQL.add(sql);
}
o.columnIndexExpr = ValueExpression.get(ValueInt.get(idx + 1));
Expression expr = expressions.get(idx).getNonAliasExpression();
o.expression = expr;
}
}
public String getPlanSQL() {
// can not use the field sqlStatement because the parameter
// indexes may be incorrect: ? may be in fact ?2 for a subquery
// but indexes may be set manually as well
Expression[] exprList = expressions.toArray(new Expression[expressions.size()]);
StatementBuilder buff = new StatementBuilder("SELECT");
if (distinct) {
buff.append(" DISTINCT");
}
for (int i = 0; i < visibleColumnCount; i++) {
buff.appendExceptFirst(",");
buff.append('\n');
buff.append(StringUtils.indent(exprList[i].getSQL(), 4, false));
}
buff.append("\nFROM ");
TableFilter filter = topTableFilter;
if (filter != null) {
buff.resetCount();
int i = 0;
do {
buff.appendExceptFirst("\n");
buff.append(filter.getPlanSQL(i++ > 0));
filter = filter.getJoin();
} while (filter != null);
} else {
buff.resetCount();
int i = 0;
for (TableFilter f : topFilters) {
do {
buff.appendExceptFirst("\n");
buff.append(f.getPlanSQL(i++ > 0));
f = f.getJoin();
} while (f != null);
}
}
if (condition != null) {
buff.append("\nWHERE ").append(StringUtils.unEnclose(condition.getSQL()));
}
if (groupIndex != null) {
buff.append("\nGROUP BY ");
buff.resetCount();
for (int gi : groupIndex) {
Expression g = exprList[gi];
g = g.getNonAliasExpression();
buff.appendExceptFirst(", ");
buff.append(StringUtils.unEnclose(g.getSQL()));
}
}
if (group != null) {
buff.append("\nGROUP BY ");
buff.resetCount();
for (Expression g : group) {
buff.appendExceptFirst(", ");
buff.append(StringUtils.unEnclose(g.getSQL()));
}
}
if (having != null) {
// could be set in addGlobalCondition
// in this case the query is not run directly, just getPlanSQL is
// called
Expression h = having;
buff.append("\nHAVING ").append(StringUtils.unEnclose(h.getSQL()));
} else if (havingIndex >= 0) {
Expression h = exprList[havingIndex];
buff.append("\nHAVING ").append(StringUtils.unEnclose(h.getSQL()));
}
if (sort != null) {
buff.append("\nORDER BY ").append(sort.getSQL(exprList, visibleColumnCount));
}
if (orderList != null) {
buff.append("\nORDER BY ");
buff.resetCount();
for (SelectOrderBy o : orderList) {
buff.appendExceptFirst(", ");
buff.append(StringUtils.unEnclose(o.getSQL()));
}
}
if (limitExpr != null) {
buff.append("\nLIMIT ").append(StringUtils.unEnclose(limitExpr.getSQL()));
if (offsetExpr != null) {
buff.append(" OFFSET ").append(StringUtils.unEnclose(offsetExpr.getSQL()));
}
}
if (sampleSize != 0) {
buff.append("\nSAMPLE_SIZE ").append(sampleSize);
}
if (isForUpdate) {
buff.append("\nFOR UPDATE");
}
if (isQuickAggregateQuery) {
buff.append("\n/* direct lookup */");
}
if (isDistinctQuery) {
buff.append("\n/* distinct */");
}
if (sortUsingIndex) {
buff.append("\n/* index sorted */");
}
if (isGroupQuery) {
if (isGroupSortedQuery) {
buff.append("\n/* group sorted */");
}
}
// buff.append("\n/* cost: " + cost + " */");
return buff.toString();
}
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;
}
public void init() {
if (SysProperties.CHECK && checkInit) {
DbException.throwInternalError();
}
expandColumnList();
visibleColumnCount = expressions.size();
ArrayList<String> expressionSQL;
if (orderList != null || group != null) {
expressionSQL = New.arrayList();
for (int i = 0; i < visibleColumnCount; i++) {
Expression expr = expressions.get(i);
expr = expr.getNonAliasExpression();
String sql = expr.getSQL();
expressionSQL.add(sql);
}
} else {
expressionSQL = null;
}
if (orderList != null) {
initOrder(
session, expressions, expressionSQL, orderList, visibleColumnCount, distinct, filters);
}
distinctColumnCount = expressions.size();
if (having != null) {
expressions.add(having);
havingIndex = expressions.size() - 1;
having = null;
} else {
havingIndex = -1;
}
Database db = session.getDatabase();
// first the select list (visible columns),
// then 'ORDER BY' expressions,
// then 'HAVING' expressions,
// and 'GROUP BY' expressions at the end
if (group != null) {
int size = group.size();
int expSize = expressionSQL.size();
groupIndex = new int[size];
for (int i = 0; i < size; i++) {
Expression expr = group.get(i);
String sql = expr.getSQL();
int found = -1;
for (int j = 0; j < expSize; j++) {
String s2 = expressionSQL.get(j);
if (db.equalsIdentifiers(s2, sql)) {
found = j;
break;
}
}
if (found < 0) {
// special case: GROUP BY a column alias
for (int j = 0; j < expSize; j++) {
Expression e = expressions.get(j);
if (db.equalsIdentifiers(sql, e.getAlias())) {
found = j;
break;
}
}
}
if (found < 0) {
int index = expressions.size();
groupIndex[i] = index;
expressions.add(expr);
} else {
groupIndex[i] = found;
}
}
groupByExpression = new boolean[expressions.size()];
for (int gi : groupIndex) {
groupByExpression[gi] = true;
}
group = null;
}
// map columns in select list and condition
for (TableFilter f : filters) {
for (Expression expr : expressions) {
expr.mapColumns(f, 0);
}
if (condition != null) {
condition.mapColumns(f, 0);
}
}
if (havingIndex >= 0) {
Expression expr = expressions.get(havingIndex);
SelectListColumnResolver res = new SelectListColumnResolver(this);
expr.mapColumns(res, 0);
}
checkInit = true;
}
/**
* Get the index that matches the ORDER BY list, if one exists. This is to avoid running a
* separate ORDER BY if an index can be used. This is specially important for large result sets,
* if only the first few rows are important (LIMIT is used)
*
* @return the index if one is found
*/
private Index getSortIndex() {
if (sort == null) {
return null;
}
ArrayList<Column> sortColumns = New.arrayList();
for (int idx : sort.getIndexes()) {
if (idx < 0 || idx >= expressions.size()) {
throw DbException.getInvalidValueException("ORDER BY", idx + 1);
}
Expression expr = expressions.get(idx);
expr = expr.getNonAliasExpression();
if (expr.isConstant()) {
continue;
}
if (!(expr instanceof ExpressionColumn)) {
return null;
}
ExpressionColumn exprCol = (ExpressionColumn) expr;
if (exprCol.getTableFilter() != topTableFilter) {
return null;
}
sortColumns.add(exprCol.getColumn());
}
Column[] sortCols = sortColumns.toArray(new Column[sortColumns.size()]);
int[] sortTypes = sort.getSortTypes();
if (sortCols.length == 0) {
// sort just on constants - can use scan index
return topTableFilter.getTable().getScanIndex(session);
}
ArrayList<Index> list = topTableFilter.getTable().getIndexes();
if (list != null) {
for (int i = 0, size = list.size(); i < size; i++) {
Index index = list.get(i);
if (index.getCreateSQL() == null) {
// can't use the scan index
continue;
}
if (index.getIndexType().isHash()) {
continue;
}
IndexColumn[] indexCols = index.getIndexColumns();
if (indexCols.length < sortCols.length) {
continue;
}
boolean ok = true;
for (int j = 0; j < sortCols.length; j++) {
// the index and the sort order must start
// with the exact same columns
IndexColumn idxCol = indexCols[j];
Column sortCol = sortCols[j];
if (idxCol.column != sortCol) {
ok = false;
break;
}
if (idxCol.sortType != sortTypes[j]) {
// NULL FIRST for ascending and NULLS LAST
// for descending would actually match the default
ok = false;
break;
}
}
if (ok) {
return index;
}
}
}
if (sortCols.length == 1 && sortCols[0].getColumnId() == -1) {
// special case: order by _ROWID_
Index index = topTableFilter.getTable().getScanIndex(session);
if (index.isRowIdIndex()) {
return index;
}
}
return null;
}
