ClickHouse/src/Interpreters/IdentifierSemantic.cpp
2021-07-08 13:49:13 +03:00

315 lines
10 KiB
C++

#include <Interpreters/IdentifierSemantic.h>
#include <Common/typeid_cast.h>
#include <Interpreters/Context.h>
#include <Interpreters/StorageID.h>
#include <Parsers/ASTFunction.h>
namespace DB
{
namespace ErrorCodes
{
extern const int AMBIGUOUS_COLUMN_NAME;
}
namespace
{
template <typename T>
std::optional<size_t> tryChooseTable(const ASTIdentifier & identifier, const std::vector<T> & tables,
bool allow_ambiguous, bool column_match [[maybe_unused]] = false)
{
using ColumnMatch = IdentifierSemantic::ColumnMatch;
size_t best_table_pos = 0;
auto best_match = ColumnMatch::NoMatch;
size_t same_match = 0;
for (size_t i = 0; i < tables.size(); ++i)
{
auto match = IdentifierSemantic::canReferColumnToTable(identifier, tables[i]);
if constexpr (std::is_same_v<T, TableWithColumnNamesAndTypes>)
{
if (column_match && match == ColumnMatch::NoMatch && identifier.isShort() && tables[i].hasColumn(identifier.shortName()))
match = ColumnMatch::ColumnName;
}
if (match != ColumnMatch::NoMatch)
{
if (match > best_match)
{
best_match = match;
best_table_pos = i;
same_match = 0;
}
else if (match == best_match)
++same_match;
}
}
if ((best_match != ColumnMatch::NoMatch) && same_match)
{
if (!allow_ambiguous)
throw Exception("Ambiguous column '" + identifier.name() + "'", ErrorCodes::AMBIGUOUS_COLUMN_NAME);
best_match = ColumnMatch::Ambiguous;
return {};
}
if (best_match != ColumnMatch::NoMatch)
return best_table_pos;
return {};
}
}
std::optional<String> IdentifierSemantic::getColumnName(const ASTIdentifier & node)
{
if (!node.semantic->special)
return node.name();
return {};
}
std::optional<String> IdentifierSemantic::getColumnName(const ASTPtr & ast)
{
if (ast)
if (const auto * id = ast->as<ASTIdentifier>())
if (!id->semantic->special)
return id->name();
return {};
}
std::optional<ASTIdentifier> IdentifierSemantic::uncover(const ASTIdentifier & identifier)
{
if (identifier.semantic->covered)
{
std::vector<String> name_parts = identifier.name_parts;
return ASTIdentifier(std::move(name_parts));
}
return {};
}
void IdentifierSemantic::coverName(ASTIdentifier & identifier, const String & alias)
{
identifier.setShortName(alias);
identifier.semantic->covered = true;
}
bool IdentifierSemantic::canBeAlias(const ASTIdentifier & identifier)
{
return identifier.semantic->can_be_alias;
}
void IdentifierSemantic::setMembership(ASTIdentifier & identifier, size_t table_pos)
{
identifier.semantic->membership = table_pos;
identifier.semantic->can_be_alias = false;
}
std::optional<size_t> IdentifierSemantic::getMembership(const ASTIdentifier & identifier)
{
return identifier.semantic->membership;
}
std::optional<size_t> IdentifierSemantic::chooseTable(const ASTIdentifier & identifier, const std::vector<DatabaseAndTableWithAlias> & tables,
bool ambiguous)
{
return tryChooseTable<DatabaseAndTableWithAlias>(identifier, tables, ambiguous);
}
std::optional<size_t> IdentifierSemantic::chooseTable(const ASTIdentifier & identifier, const TablesWithColumns & tables, bool ambiguous)
{
return tryChooseTable<TableWithColumnNamesAndTypes>(identifier, tables, ambiguous);
}
std::optional<size_t> IdentifierSemantic::chooseTableColumnMatch(const ASTIdentifier & identifier, const TablesWithColumns & tables,
bool ambiguous)
{
return tryChooseTable<TableWithColumnNamesAndTypes>(identifier, tables, ambiguous, true);
}
std::optional<String> IdentifierSemantic::extractNestedName(const ASTIdentifier & identifier, const String & table_name)
{
if (identifier.name_parts.size() == 3 && table_name == identifier.name_parts[0])
return identifier.name_parts[1] + '.' + identifier.name_parts[2];
else if (identifier.name_parts.size() == 2)
return identifier.name_parts[0] + '.' + identifier.name_parts[1];
return {};
}
bool IdentifierSemantic::doesIdentifierBelongTo(const ASTIdentifier & identifier, const String & database, const String & table)
{
size_t num_components = identifier.name_parts.size();
if (num_components >= 3)
return identifier.name_parts[0] == database &&
identifier.name_parts[1] == table;
return false;
}
bool IdentifierSemantic::doesIdentifierBelongTo(const ASTIdentifier & identifier, const String & table)
{
size_t num_components = identifier.name_parts.size();
if (num_components >= 2)
return identifier.name_parts[0] == table;
return false;
}
IdentifierSemantic::ColumnMatch IdentifierSemantic::canReferColumnToTable(const ASTIdentifier & identifier,
const DatabaseAndTableWithAlias & db_and_table)
{
/// database.table.column
if (doesIdentifierBelongTo(identifier, db_and_table.database, db_and_table.table))
return ColumnMatch::DbAndTable;
/// alias.column
if (doesIdentifierBelongTo(identifier, db_and_table.alias))
return ColumnMatch::TableAlias;
/// table.column
if (doesIdentifierBelongTo(identifier, db_and_table.table))
{
if (!db_and_table.alias.empty())
return ColumnMatch::AliasedTableName;
else
return ColumnMatch::TableName;
}
return ColumnMatch::NoMatch;
}
IdentifierSemantic::ColumnMatch IdentifierSemantic::canReferColumnToTable(const ASTIdentifier & identifier,
const TableWithColumnNamesAndTypes & table_with_columns)
{
return canReferColumnToTable(identifier, table_with_columns.table);
}
/// Strip qualifications from left side of column name.
/// Example: 'database.table.name' -> 'name'.
void IdentifierSemantic::setColumnShortName(ASTIdentifier & identifier, const DatabaseAndTableWithAlias & db_and_table)
{
auto match = IdentifierSemantic::canReferColumnToTable(identifier, db_and_table);
size_t to_strip = 0;
switch (match)
{
case ColumnMatch::TableName:
case ColumnMatch::AliasedTableName:
case ColumnMatch::TableAlias:
to_strip = 1;
break;
case ColumnMatch::DbAndTable:
to_strip = 2;
break;
default:
break;
}
if (!to_strip)
return;
identifier.name_parts = std::vector<String>(identifier.name_parts.begin() + to_strip, identifier.name_parts.end());
identifier.resetFullName();
}
void IdentifierSemantic::setColumnLongName(ASTIdentifier & identifier, const DatabaseAndTableWithAlias & db_and_table)
{
String prefix = db_and_table.getQualifiedNamePrefix();
if (!prefix.empty())
{
prefix.resize(prefix.size() - 1); /// crop dot
identifier.name_parts = {prefix, identifier.shortName()};
identifier.resetFullName();
identifier.semantic->table = prefix;
identifier.semantic->legacy_compound = true;
}
}
std::optional<size_t> IdentifierSemantic::getIdentMembership(const ASTIdentifier & ident, const std::vector<TableWithColumnNamesAndTypes> & tables)
{
std::optional<size_t> table_pos = IdentifierSemantic::getMembership(ident);
if (table_pos)
return table_pos;
return IdentifierSemantic::chooseTableColumnMatch(ident, tables, true);
}
std::optional<size_t>
IdentifierSemantic::getIdentsMembership(ASTPtr ast, const std::vector<TableWithColumnNamesAndTypes> & tables, const Aliases & aliases)
{
auto idents = IdentifiersCollector::collect(ast);
std::optional<size_t> result;
for (const auto * ident : idents)
{
/// short name clashes with alias, ambiguous
if (ident->isShort() && aliases.count(ident->shortName()))
return {};
const auto pos = getIdentMembership(*ident, tables);
if (!pos)
return {};
/// identifiers from different tables
if (result && *pos != *result)
return {};
result = pos;
}
return result;
}
IdentifiersCollector::ASTIdentifiers IdentifiersCollector::collect(const ASTPtr & node)
{
IdentifiersCollector::Data ident_data;
ConstInDepthNodeVisitor<IdentifiersCollector, true> ident_visitor(ident_data);
ident_visitor.visit(node);
return ident_data.idents;
}
bool IdentifiersCollector::needChildVisit(const ASTPtr &, const ASTPtr &)
{
return true;
}
void IdentifiersCollector::visit(const ASTPtr & node, IdentifiersCollector::Data & data)
{
if (const auto * ident = node->as<ASTIdentifier>())
data.idents.push_back(ident);
}
IdentifierMembershipCollector::IdentifierMembershipCollector(const ASTSelectQuery & select, ContextPtr context)
{
if (ASTPtr with = select.with())
QueryAliasesNoSubqueriesVisitor(aliases).visit(with);
QueryAliasesNoSubqueriesVisitor(aliases).visit(select.select());
const auto & settings = context->getSettingsRef();
tables = getDatabaseAndTablesWithColumns(getTableExpressions(select), context,
settings.asterisk_include_alias_columns,
settings.asterisk_include_materialized_columns);
}
std::optional<size_t> IdentifierMembershipCollector::getIdentsMembership(ASTPtr ast) const
{
return IdentifierSemantic::getIdentsMembership(ast, tables, aliases);
}
static void collectConjunctions(const ASTPtr & node, std::vector<ASTPtr> & members)
{
if (const auto * func = node->as<ASTFunction>(); func && func->name == "and")
{
for (const auto & child : func->arguments->children)
collectConjunctions(child, members);
return;
}
members.push_back(node);
}
std::vector<ASTPtr> collectConjunctions(const ASTPtr & node)
{
std::vector<ASTPtr> members;
collectConjunctions(node, members);
return members;
}
}