ClickHouse/src/Interpreters/SyntaxAnalyzer.cpp

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#include <Core/Settings.h>
#include <Core/Defines.h>
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#include <Core/NamesAndTypes.h>
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#include <Interpreters/SyntaxAnalyzer.h>
#include <Interpreters/LogicalExpressionsOptimizer.h>
#include <Interpreters/QueryAliasesVisitor.h>
#include <Interpreters/InterpreterSelectWithUnionQuery.h>
#include <Interpreters/ArrayJoinedColumnsVisitor.h>
#include <Interpreters/TranslateQualifiedNamesVisitor.h>
#include <Interpreters/Context.h>
#include <Interpreters/MarkTableIdentifiersVisitor.h>
#include <Interpreters/QueryNormalizer.h>
#include <Interpreters/ExecuteScalarSubqueriesVisitor.h>
#include <Interpreters/PredicateExpressionsOptimizer.h>
#include <Interpreters/CollectJoinOnKeysVisitor.h>
#include <Interpreters/ExternalDictionariesLoader.h>
#include <Interpreters/OptimizeIfWithConstantConditionVisitor.h>
#include <Interpreters/RequiredSourceColumnsVisitor.h>
#include <Interpreters/GetAggregatesVisitor.h>
#include <Interpreters/TableJoin.h>
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#include <Interpreters/ExpressionActions.h> /// getSmallestColumn()
#include <Interpreters/getTableExpressions.h>
#include <Interpreters/OptimizeIfChains.h>
#include <Parsers/ASTExpressionList.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTLiteral.h>
#include <Parsers/ASTOrderByElement.h>
#include <Parsers/ASTSelectQuery.h>
#include <Parsers/ASTTablesInSelectQuery.h>
#include <Parsers/queryToString.h>
#include <Functions/FunctionFactory.h>
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#include <DataTypes/NestedUtils.h>
#include <DataTypes/DataTypeNullable.h>
#include <IO/WriteHelpers.h>
#include <Storages/IStorage.h>
#include <functional>
namespace DB
{
namespace ErrorCodes
{
extern const int EMPTY_NESTED_TABLE;
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extern const int LOGICAL_ERROR;
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extern const int INVALID_JOIN_ON_EXPRESSION;
extern const int EMPTY_LIST_OF_COLUMNS_QUERIED;
extern const int NOT_IMPLEMENTED;
extern const int UNKNOWN_IDENTIFIER;
extern const int EXPECTED_ALL_OR_ANY;
}
namespace
{
using LogAST = DebugASTLog<false>; /// set to true to enable logs
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/// Select implementation of a function based on settings.
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/// Important that it is done as query rewrite. It means rewritten query
/// will be sent to remote servers during distributed query execution,
/// and on all remote servers, function implementation will be same.
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template <char const * func_name>
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struct CustomizeFunctionsData
{
using TypeToVisit = ASTFunction;
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const String & customized_func_name;
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void visit(ASTFunction & func, ASTPtr &)
{
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if (Poco::toLower(func.name) == func_name)
{
func.name = customized_func_name;
}
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}
};
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char countdistinct[] = "countdistinct";
using CustomizeFunctionsVisitor = InDepthNodeVisitor<OneTypeMatcher<CustomizeFunctionsData<countdistinct>>, true>;
char in[] = "in";
using CustomizeInVisitor = InDepthNodeVisitor<OneTypeMatcher<CustomizeFunctionsData<in>>, true>;
char notIn[] = "notin";
using CustomizeNotInVisitor = InDepthNodeVisitor<OneTypeMatcher<CustomizeFunctionsData<notIn>>, true>;
char globalIn[] = "globalin";
using CustomizeGlobalInVisitor = InDepthNodeVisitor<OneTypeMatcher<CustomizeFunctionsData<globalIn>>, true>;
char globalNotIn[] = "globalnotin";
using CustomizeGlobalNotInVisitor = InDepthNodeVisitor<OneTypeMatcher<CustomizeFunctionsData<globalNotIn>>, true>;
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/// Translate qualified names such as db.table.column, table.column, table_alias.column to names' normal form.
/// Expand asterisks and qualified asterisks with column names.
/// There would be columns in normal form & column aliases after translation. Column & column alias would be normalized in QueryNormalizer.
void translateQualifiedNames(ASTPtr & query, const ASTSelectQuery & select_query, const NameSet & source_columns_set,
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const std::vector<TableWithColumnNames> & tables_with_columns)
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{
LogAST log;
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TranslateQualifiedNamesVisitor::Data visitor_data(source_columns_set, tables_with_columns);
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TranslateQualifiedNamesVisitor visitor(visitor_data, log.stream());
visitor.visit(query);
/// This may happen after expansion of COLUMNS('regexp').
if (select_query.select()->children.empty())
throw Exception("Empty list of columns in SELECT query", ErrorCodes::EMPTY_LIST_OF_COLUMNS_QUERIED);
}
bool hasArrayJoin(const ASTPtr & ast)
{
if (const ASTFunction * function = ast->as<ASTFunction>())
if (function->name == "arrayJoin")
return true;
for (const auto & child : ast->children)
if (!child->as<ASTSelectQuery>() && hasArrayJoin(child))
return true;
return false;
}
/// Keep number of columns for 'GLOBAL IN (SELECT 1 AS a, a)'
void renameDuplicatedColumns(const ASTSelectQuery * select_query)
{
ASTs & elements = select_query->select()->children;
std::set<String> all_column_names;
std::set<String> assigned_column_names;
for (auto & expr : elements)
all_column_names.insert(expr->getAliasOrColumnName());
for (auto & expr : elements)
{
auto name = expr->getAliasOrColumnName();
if (!assigned_column_names.insert(name).second)
{
size_t i = 1;
while (all_column_names.end() != all_column_names.find(name + "_" + toString(i)))
++i;
name = name + "_" + toString(i);
expr = expr->clone(); /// Cancels fuse of the same expressions in the tree.
expr->setAlias(name);
all_column_names.insert(name);
assigned_column_names.insert(name);
}
}
}
/// Sometimes we have to calculate more columns in SELECT clause than will be returned from query.
/// This is the case when we have DISTINCT or arrayJoin: we require more columns in SELECT even if we need less columns in result.
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/// Also we have to remove duplicates in case of GLOBAL subqueries. Their results are placed into tables so duplicates are impossible.
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void removeUnneededColumnsFromSelectClause(const ASTSelectQuery * select_query, const Names & required_result_columns, bool remove_dups)
{
ASTs & elements = select_query->select()->children;
std::map<String, size_t> required_columns_with_duplicate_count;
if (!required_result_columns.empty())
{
/// Some columns may be queried multiple times, like SELECT x, y, y FROM table.
for (const auto & name : required_result_columns)
{
if (remove_dups)
required_columns_with_duplicate_count[name] = 1;
else
++required_columns_with_duplicate_count[name];
}
}
else if (remove_dups)
{
/// Even if we have no requirements there could be duplicates cause of asterisks. SELECT *, t.*
for (const auto & elem : elements)
required_columns_with_duplicate_count.emplace(elem->getAliasOrColumnName(), 1);
}
else
return;
ASTs new_elements;
new_elements.reserve(elements.size());
for (const auto & elem : elements)
{
String name = elem->getAliasOrColumnName();
auto it = required_columns_with_duplicate_count.find(name);
if (required_columns_with_duplicate_count.end() != it && it->second)
{
new_elements.push_back(elem);
--it->second;
}
else if (select_query->distinct || hasArrayJoin(elem))
{
new_elements.push_back(elem);
}
}
elements = std::move(new_elements);
}
/// Replacing scalar subqueries with constant values.
void executeScalarSubqueries(ASTPtr & query, const Context & context, size_t subquery_depth, Scalars & scalars)
{
LogAST log;
ExecuteScalarSubqueriesVisitor::Data visitor_data{context, subquery_depth, scalars};
ExecuteScalarSubqueriesVisitor(visitor_data, log.stream()).visit(query);
}
const std::unordered_set<String> possibly_injective_function_names
{
"dictGetString",
"dictGetUInt8",
"dictGetUInt16",
"dictGetUInt32",
"dictGetUInt64",
"dictGetInt8",
"dictGetInt16",
"dictGetInt32",
"dictGetInt64",
"dictGetFloat32",
"dictGetFloat64",
"dictGetDate",
"dictGetDateTime"
};
/** You can not completely remove GROUP BY. Because if there were no aggregate functions, then it turns out that there will be no aggregation.
* Instead, leave `GROUP BY const`.
* Next, see deleting the constants in the analyzeAggregation method.
*/
void appendUnusedGroupByColumn(ASTSelectQuery * select_query, const NameSet & source_columns)
{
/// You must insert a constant that is not the name of the column in the table. Such a case is rare, but it happens.
UInt64 unused_column = 0;
String unused_column_name = toString(unused_column);
while (source_columns.count(unused_column_name))
{
++unused_column;
unused_column_name = toString(unused_column);
}
select_query->setExpression(ASTSelectQuery::Expression::GROUP_BY, std::make_shared<ASTExpressionList>());
select_query->groupBy()->children.emplace_back(std::make_shared<ASTLiteral>(UInt64(unused_column)));
}
/// Eliminates injective function calls and constant expressions from group by statement.
void optimizeGroupBy(ASTSelectQuery * select_query, const NameSet & source_columns, const Context & context)
{
const FunctionFactory & function_factory = FunctionFactory::instance();
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if (!select_query->groupBy())
{
// If there is a HAVING clause without GROUP BY, make sure we have some aggregation happen.
if (select_query->having())
appendUnusedGroupByColumn(select_query, source_columns);
return;
}
const auto is_literal = [] (const ASTPtr & ast) -> bool
{
return ast->as<ASTLiteral>();
};
auto & group_exprs = select_query->groupBy()->children;
/// removes expression at index idx by making it last one and calling .pop_back()
const auto remove_expr_at_index = [&group_exprs] (const size_t idx)
{
if (idx < group_exprs.size() - 1)
std::swap(group_exprs[idx], group_exprs.back());
group_exprs.pop_back();
};
/// iterate over each GROUP BY expression, eliminate injective function calls and literals
for (size_t i = 0; i < group_exprs.size();)
{
if (const auto * function = group_exprs[i]->as<ASTFunction>())
{
/// assert function is injective
if (possibly_injective_function_names.count(function->name))
{
/// do not handle semantic errors here
if (function->arguments->children.size() < 2)
{
++i;
continue;
}
const auto & dict_name = function->arguments->children[0]->as<ASTLiteral &>().value.safeGet<String>();
const auto & dict_ptr = context.getExternalDictionariesLoader().getDictionary(dict_name);
const auto & attr_name = function->arguments->children[1]->as<ASTLiteral &>().value.safeGet<String>();
if (!dict_ptr->isInjective(attr_name))
{
++i;
continue;
}
}
else if (!function_factory.get(function->name, context)->isInjective(Block{}))
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{
++i;
continue;
}
/// copy shared pointer to args in order to ensure lifetime
auto args_ast = function->arguments;
/** remove function call and take a step back to ensure
* next iteration does not skip not yet processed data
*/
remove_expr_at_index(i);
/// copy non-literal arguments
std::remove_copy_if(
std::begin(args_ast->children), std::end(args_ast->children),
std::back_inserter(group_exprs), is_literal
);
}
else if (is_literal(group_exprs[i]))
{
remove_expr_at_index(i);
}
else
{
/// if neither a function nor literal - advance to next expression
++i;
}
}
if (group_exprs.empty())
appendUnusedGroupByColumn(select_query, source_columns);
}
/// Remove duplicate items from ORDER BY.
void optimizeOrderBy(const ASTSelectQuery * select_query)
{
if (!select_query->orderBy())
return;
/// Make unique sorting conditions.
using NameAndLocale = std::pair<String, String>;
std::set<NameAndLocale> elems_set;
ASTs & elems = select_query->orderBy()->children;
ASTs unique_elems;
unique_elems.reserve(elems.size());
for (const auto & elem : elems)
{
String name = elem->children.front()->getColumnName();
const auto & order_by_elem = elem->as<ASTOrderByElement &>();
if (elems_set.emplace(name, order_by_elem.collation ? order_by_elem.collation->getColumnName() : "").second)
unique_elems.emplace_back(elem);
}
if (unique_elems.size() < elems.size())
elems = std::move(unique_elems);
}
/// Remove duplicate items from LIMIT BY.
void optimizeLimitBy(const ASTSelectQuery * select_query)
{
if (!select_query->limitBy())
return;
std::set<String> elems_set;
ASTs & elems = select_query->limitBy()->children;
ASTs unique_elems;
unique_elems.reserve(elems.size());
for (const auto & elem : elems)
{
if (elems_set.emplace(elem->getColumnName()).second)
unique_elems.emplace_back(elem);
}
if (unique_elems.size() < elems.size())
elems = std::move(unique_elems);
}
/// Remove duplicated columns from USING(...).
void optimizeUsing(const ASTSelectQuery * select_query)
{
if (!select_query->join())
return;
const auto * table_join = select_query->join()->table_join->as<ASTTableJoin>();
if (!(table_join && table_join->using_expression_list))
return;
ASTs & expression_list = table_join->using_expression_list->children;
ASTs uniq_expressions_list;
std::set<String> expressions_names;
for (const auto & expression : expression_list)
{
auto expression_name = expression->getAliasOrColumnName();
if (expressions_names.find(expression_name) == expressions_names.end())
{
uniq_expressions_list.push_back(expression);
expressions_names.insert(expression_name);
}
}
if (uniq_expressions_list.size() < expression_list.size())
expression_list = uniq_expressions_list;
}
void optimizeIf(ASTPtr & query, Aliases & aliases, bool if_chain_to_miltiif)
{
/// Optimize if with constant condition after constants was substituted instead of scalar subqueries.
OptimizeIfWithConstantConditionVisitor(aliases).visit(query);
if (if_chain_to_miltiif)
OptimizeIfChainsVisitor().visit(query);
}
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void getArrayJoinedColumns(ASTPtr & query, SyntaxAnalyzerResult & result, const ASTSelectQuery * select_query,
const NamesAndTypesList & source_columns, const NameSet & source_columns_set)
{
if (ASTPtr array_join_expression_list = select_query->arrayJoinExpressionList())
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{
ArrayJoinedColumnsVisitor::Data visitor_data{result.aliases,
result.array_join_name_to_alias,
result.array_join_alias_to_name,
result.array_join_result_to_source};
ArrayJoinedColumnsVisitor(visitor_data).visit(query);
/// If the result of ARRAY JOIN is not used, it is necessary to ARRAY-JOIN any column,
/// to get the correct number of rows.
if (result.array_join_result_to_source.empty())
{
ASTPtr expr = select_query->arrayJoinExpressionList()->children.at(0);
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String source_name = expr->getColumnName();
String result_name = expr->getAliasOrColumnName();
/// This is an array.
if (!expr->as<ASTIdentifier>() || source_columns_set.count(source_name))
{
result.array_join_result_to_source[result_name] = source_name;
}
else /// This is a nested table.
{
bool found = false;
for (const auto & column : source_columns)
{
auto splitted = Nested::splitName(column.name);
if (splitted.first == source_name && !splitted.second.empty())
{
result.array_join_result_to_source[Nested::concatenateName(result_name, splitted.second)] = column.name;
found = true;
break;
}
}
if (!found)
throw Exception("No columns in nested table " + source_name, ErrorCodes::EMPTY_NESTED_TABLE);
}
}
}
}
void setJoinStrictness(ASTSelectQuery & select_query, JoinStrictness join_default_strictness, bool old_any, ASTTableJoin & out_table_join)
{
const ASTTablesInSelectQueryElement * node = select_query.join();
if (!node)
return;
auto & table_join = const_cast<ASTTablesInSelectQueryElement *>(node)->table_join->as<ASTTableJoin &>();
if (table_join.strictness == ASTTableJoin::Strictness::Unspecified &&
table_join.kind != ASTTableJoin::Kind::Cross)
{
if (join_default_strictness == JoinStrictness::ANY)
table_join.strictness = ASTTableJoin::Strictness::Any;
else if (join_default_strictness == JoinStrictness::ALL)
table_join.strictness = ASTTableJoin::Strictness::All;
else
throw Exception("Expected ANY or ALL in JOIN section, because setting (join_default_strictness) is empty",
DB::ErrorCodes::EXPECTED_ALL_OR_ANY);
}
if (old_any)
{
if (table_join.strictness == ASTTableJoin::Strictness::Any &&
table_join.kind == ASTTableJoin::Kind::Inner)
{
table_join.strictness = ASTTableJoin::Strictness::Semi;
table_join.kind = ASTTableJoin::Kind::Left;
}
if (table_join.strictness == ASTTableJoin::Strictness::Any)
table_join.strictness = ASTTableJoin::Strictness::RightAny;
}
else
{
if (table_join.strictness == ASTTableJoin::Strictness::Any)
if (table_join.kind == ASTTableJoin::Kind::Full)
throw Exception("ANY FULL JOINs are not implemented.", ErrorCodes::NOT_IMPLEMENTED);
}
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out_table_join = table_join;
}
/// Find the columns that are obtained by JOIN.
void collectJoinedColumns(TableJoin & analyzed_join, const ASTSelectQuery & select_query,
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const std::vector<TableWithColumnNames> & tables, const Aliases & aliases)
{
const ASTTablesInSelectQueryElement * node = select_query.join();
if (!node)
return;
const auto & table_join = node->table_join->as<ASTTableJoin &>();
if (table_join.using_expression_list)
{
const auto & keys = table_join.using_expression_list->as<ASTExpressionList &>();
for (const auto & key : keys.children)
analyzed_join.addUsingKey(key);
}
else if (table_join.on_expression)
{
bool is_asof = (table_join.strictness == ASTTableJoin::Strictness::Asof);
CollectJoinOnKeysVisitor::Data data{analyzed_join, tables[0], tables[1], aliases, is_asof};
CollectJoinOnKeysVisitor(data).visit(table_join.on_expression);
if (!data.has_some)
throw Exception("Cannot get JOIN keys from JOIN ON section: " + queryToString(table_join.on_expression),
ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
if (is_asof)
data.asofToJoinKeys();
}
}
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std::vector<const ASTFunction *> getAggregates(ASTPtr & query, const ASTSelectQuery & select_query)
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{
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/// There can not be aggregate functions inside the WHERE and PREWHERE.
if (select_query.where())
assertNoAggregates(select_query.where(), "in WHERE");
if (select_query.prewhere())
assertNoAggregates(select_query.prewhere(), "in PREWHERE");
GetAggregatesVisitor::Data data;
GetAggregatesVisitor(data).visit(query);
/// There can not be other aggregate functions within the aggregate functions.
for (const ASTFunction * node : data.aggregates)
for (auto & arg : node->arguments->children)
assertNoAggregates(arg, "inside another aggregate function");
return data.aggregates;
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}
}
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/// Add columns from storage to source_columns list. Deduplicate resulted list.
void SyntaxAnalyzerResult::collectSourceColumns(bool add_virtuals)
{
if (storage)
{
const ColumnsDescription & columns = storage->getColumns();
auto columns_from_storage = add_virtuals ? columns.getAll() : columns.getAllPhysical();
if (source_columns.empty())
source_columns.swap(columns_from_storage);
else
source_columns.insert(source_columns.end(), columns_from_storage.begin(), columns_from_storage.end());
}
source_columns_set = removeDuplicateColumns(source_columns);
}
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/// Calculate which columns are required to execute the expression.
/// Then, delete all other columns from the list of available columns.
/// After execution, columns will only contain the list of columns needed to read from the table.
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void SyntaxAnalyzerResult::collectUsedColumns(const ASTPtr & query)
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{
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/// We calculate required_source_columns with source_columns modifications and swap them on exit
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required_source_columns = source_columns;
RequiredSourceColumnsVisitor::Data columns_context;
RequiredSourceColumnsVisitor(columns_context).visit(query);
NameSet source_column_names;
for (const auto & column : source_columns)
source_column_names.insert(column.name);
NameSet required = columns_context.requiredColumns();
if (columns_context.has_table_join)
{
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NameSet available_columns;
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for (const auto & name : source_columns)
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available_columns.insert(name.name);
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/// Add columns obtained by JOIN (if needed).
for (const auto & joined_column : analyzed_join->columnsFromJoinedTable())
{
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const auto & name = joined_column.name;
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if (available_columns.count(name))
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continue;
if (required.count(name))
{
/// Optimisation: do not add columns needed only in JOIN ON section.
if (columns_context.nameInclusion(name) > analyzed_join->rightKeyInclusion(name))
analyzed_join->addJoinedColumn(joined_column);
required.erase(name);
}
}
}
NameSet array_join_sources;
if (columns_context.has_array_join)
{
/// Insert the columns required for the ARRAY JOIN calculation into the required columns list.
for (const auto & result_source : array_join_result_to_source)
array_join_sources.insert(result_source.second);
for (const auto & column_name_type : source_columns)
if (array_join_sources.count(column_name_type.name))
required.insert(column_name_type.name);
}
const auto * select_query = query->as<ASTSelectQuery>();
/// You need to read at least one column to find the number of rows.
if (select_query && required.empty())
{
maybe_optimize_trivial_count = true;
/// We will find a column with minimum <compressed_size, type_size, uncompressed_size>.
/// Because it is the column that is cheapest to read.
struct ColumnSizeTuple
{
size_t compressed_size;
size_t type_size;
size_t uncompressed_size;
String name;
bool operator<(const ColumnSizeTuple & that) const
{
return std::tie(compressed_size, type_size, uncompressed_size)
< std::tie(that.compressed_size, that.type_size, that.uncompressed_size);
}
};
std::vector<ColumnSizeTuple> columns;
if (storage)
{
auto column_sizes = storage->getColumnSizes();
for (auto & source_column : source_columns)
{
auto c = column_sizes.find(source_column.name);
if (c == column_sizes.end())
continue;
size_t type_size = source_column.type->haveMaximumSizeOfValue() ? source_column.type->getMaximumSizeOfValueInMemory() : 100;
columns.emplace_back(ColumnSizeTuple{c->second.data_compressed, type_size, c->second.data_uncompressed, source_column.name});
}
}
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if (!columns.empty())
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required.insert(std::min_element(columns.begin(), columns.end())->name);
else
/// If we have no information about columns sizes, choose a column of minimum size of its data type.
required.insert(ExpressionActions::getSmallestColumn(source_columns));
}
NameSet unknown_required_source_columns = required;
for (NamesAndTypesList::iterator it = source_columns.begin(); it != source_columns.end();)
{
const String & column_name = it->name;
unknown_required_source_columns.erase(column_name);
if (!required.count(column_name))
source_columns.erase(it++);
else
++it;
}
/// If there are virtual columns among the unknown columns. Remove them from the list of unknown and add
/// in columns list, so that when further processing they are also considered.
if (storage)
{
for (auto it = unknown_required_source_columns.begin(); it != unknown_required_source_columns.end();)
{
if (storage->hasColumn(*it))
{
source_columns.push_back(storage->getColumn(*it));
unknown_required_source_columns.erase(it++);
}
else
++it;
}
}
if (!unknown_required_source_columns.empty())
{
std::stringstream ss;
ss << "Missing columns:";
for (const auto & name : unknown_required_source_columns)
ss << " '" << name << "'";
ss << " while processing query: '" << queryToString(query) << "'";
ss << ", required columns:";
for (const auto & name : columns_context.requiredColumns())
ss << " '" << name << "'";
if (!source_column_names.empty())
{
ss << ", source columns:";
for (const auto & name : source_column_names)
ss << " '" << name << "'";
}
else
ss << ", no source columns";
if (columns_context.has_table_join)
{
ss << ", joined columns:";
for (const auto & column : analyzed_join->columnsFromJoinedTable())
ss << " '" << column.name << "'";
}
if (!array_join_sources.empty())
{
ss << ", arrayJoin columns:";
for (const auto & name : array_join_sources)
ss << " '" << name << "'";
}
throw Exception(ss.str(), ErrorCodes::UNKNOWN_IDENTIFIER);
}
required_source_columns.swap(source_columns);
}
SyntaxAnalyzerResultPtr SyntaxAnalyzer::analyzeSelect(
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ASTPtr & query,
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SyntaxAnalyzerResult && result,
const SelectQueryOptions & select_options,
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const std::vector<TableWithColumnNamesAndTypes> & tables_with_columns,
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const Names & required_result_columns,
std::shared_ptr<TableJoin> table_join) const
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{
auto * select_query = query->as<ASTSelectQuery>();
if (!select_query)
throw Exception("Select analyze for not select asts.", ErrorCodes::LOGICAL_ERROR);
size_t subquery_depth = select_options.subquery_depth;
bool remove_duplicates = select_options.remove_duplicates;
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const auto & settings = context.getSettingsRef();
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const NameSet & source_columns_set = result.source_columns_set;
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result.analyzed_join = table_join;
if (!result.analyzed_join) /// ExpressionAnalyzer expects some not empty object here
result.analyzed_join = std::make_shared<TableJoin>();
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if (remove_duplicates)
renameDuplicatedColumns(select_query);
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/// TODO: Remove unneeded conversion
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std::vector<TableWithColumnNames> tables_with_column_names;
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tables_with_column_names.reserve(tables_with_columns.size());
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for (const auto & table : tables_with_columns)
tables_with_column_names.emplace_back(table.removeTypes());
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if (tables_with_columns.size() > 1)
{
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result.analyzed_join->columns_from_joined_table = tables_with_columns[1].columns;
result.analyzed_join->deduplicateAndQualifyColumnNames(
source_columns_set, tables_with_columns[1].table.getQualifiedNamePrefix());
}
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translateQualifiedNames(query, *select_query, source_columns_set, tables_with_column_names);
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/// Optimizes logical expressions.
LogicalExpressionsOptimizer(select_query, settings.optimize_min_equality_disjunction_chain_length.value).perform();
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normalize(query, result.aliases, settings);
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/// Remove unneeded columns according to 'required_result_columns'.
/// Leave all selected columns in case of DISTINCT; columns that contain arrayJoin function inside.
/// Must be after 'normalizeTree' (after expanding aliases, for aliases not get lost)
/// and before 'executeScalarSubqueries', 'analyzeAggregation', etc. to avoid excessive calculations.
removeUnneededColumnsFromSelectClause(select_query, required_result_columns, remove_duplicates);
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/// Executing scalar subqueries - replacing them with constant values.
executeScalarSubqueries(query, context, subquery_depth, result.scalars);
{
optimizeIf(query, result.aliases, settings.optimize_if_chain_to_miltiif);
/// Push the predicate expression down to the subqueries.
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result.rewrite_subqueries = PredicateExpressionsOptimizer(context, tables_with_column_names, settings).optimize(*select_query);
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/// GROUP BY injective function elimination.
optimizeGroupBy(select_query, source_columns_set, context);
/// Remove duplicate items from ORDER BY.
optimizeOrderBy(select_query);
/// Remove duplicated elements from LIMIT BY clause.
optimizeLimitBy(select_query);
/// Remove duplicated columns from USING(...).
optimizeUsing(select_query);
/// array_join_alias_to_name, array_join_result_to_source.
getArrayJoinedColumns(query, result, select_query, result.source_columns, source_columns_set);
setJoinStrictness(*select_query, settings.join_default_strictness, settings.any_join_distinct_right_table_keys,
result.analyzed_join->table_join);
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collectJoinedColumns(*result.analyzed_join, *select_query, tables_with_column_names, result.aliases);
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}
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result.aggregates = getAggregates(query, *select_query);
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result.collectUsedColumns(query);
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return std::make_shared<const SyntaxAnalyzerResult>(result);
}
SyntaxAnalyzerResultPtr SyntaxAnalyzer::analyze(ASTPtr & query, const NamesAndTypesList & source_columns, ConstStoragePtr storage) const
{
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if (query->as<ASTSelectQuery>())
throw Exception("Not select analyze for select asts.", ErrorCodes::LOGICAL_ERROR);
const auto & settings = context.getSettingsRef();
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SyntaxAnalyzerResult result(source_columns, storage, false);
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normalize(query, result.aliases, settings);
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/// Executing scalar subqueries. Column defaults could be a scalar subquery.
executeScalarSubqueries(query, context, 0, result.scalars);
optimizeIf(query, result.aliases, settings.optimize_if_chain_to_miltiif);
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assertNoAggregates(query, "in wrong place");
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result.collectUsedColumns(query);
return std::make_shared<const SyntaxAnalyzerResult>(result);
}
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void SyntaxAnalyzer::normalize(ASTPtr & query, Aliases & aliases, const Settings & settings)
{
CustomizeFunctionsVisitor::Data data{settings.count_distinct_implementation};
CustomizeFunctionsVisitor(data).visit(query);
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if (settings.transform_null_in)
{
CustomizeInVisitor::Data data_null_in{"nullIn"};
CustomizeInVisitor(data_null_in).visit(query);
CustomizeNotInVisitor::Data data_not_null_in{"notNullIn"};
CustomizeNotInVisitor(data_not_null_in).visit(query);
CustomizeGlobalInVisitor::Data data_global_null_in{"globalNullIn"};
CustomizeGlobalInVisitor(data_global_null_in).visit(query);
CustomizeGlobalNotInVisitor::Data data_global_not_null_in{"globalNotNullIn"};
CustomizeGlobalNotInVisitor(data_global_not_null_in).visit(query);
}
/// Creates a dictionary `aliases`: alias -> ASTPtr
QueryAliasesVisitor(aliases).visit(query);
/// Mark table ASTIdentifiers with not a column marker
MarkTableIdentifiersVisitor::Data identifiers_data{aliases};
MarkTableIdentifiersVisitor(identifiers_data).visit(query);
/// Common subexpression elimination. Rewrite rules.
QueryNormalizer::Data normalizer_data(aliases, settings);
QueryNormalizer(normalizer_data).visit(query);
}
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}