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276 lines
11 KiB
C++
276 lines
11 KiB
C++
#include <Parsers/queryToString.h>
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#include <Interpreters/CollectJoinOnKeysVisitor.h>
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#include <Interpreters/IdentifierSemantic.h>
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#include <Interpreters/TableJoin.h>
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namespace DB
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{
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namespace ErrorCodes
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{
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extern const int INVALID_JOIN_ON_EXPRESSION;
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extern const int AMBIGUOUS_COLUMN_NAME;
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extern const int SYNTAX_ERROR;
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extern const int LOGICAL_ERROR;
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}
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namespace
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{
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bool isLeftIdentifier(JoinIdentifierPos pos)
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{
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/// Unknown identifiers considered as left, we will try to process it on later stages
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/// Usually such identifiers came from `ARRAY JOIN ... AS ...`
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return pos == JoinIdentifierPos::Left || pos == JoinIdentifierPos::Unknown;
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}
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bool isRightIdentifier(JoinIdentifierPos pos)
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{
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return pos == JoinIdentifierPos::Right;
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}
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}
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void CollectJoinOnKeysMatcher::Data::addJoinKeys(const ASTPtr & left_ast, const ASTPtr & right_ast, JoinIdentifierPosPair table_pos)
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{
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ASTPtr left = left_ast->clone();
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ASTPtr right = right_ast->clone();
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if (isLeftIdentifier(table_pos.first) && isRightIdentifier(table_pos.second))
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analyzed_join.addOnKeys(left, right);
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else if (isRightIdentifier(table_pos.first) && isLeftIdentifier(table_pos.second))
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analyzed_join.addOnKeys(right, left);
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else
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throw Exception("Cannot detect left and right JOIN keys. JOIN ON section is ambiguous.",
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ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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}
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void CollectJoinOnKeysMatcher::Data::addAsofJoinKeys(const ASTPtr & left_ast, const ASTPtr & right_ast,
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JoinIdentifierPosPair table_pos, const ASOF::Inequality & inequality)
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{
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if (isLeftIdentifier(table_pos.first) && isRightIdentifier(table_pos.second))
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{
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asof_left_key = left_ast->clone();
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asof_right_key = right_ast->clone();
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analyzed_join.setAsofInequality(inequality);
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}
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else if (isRightIdentifier(table_pos.first) && isLeftIdentifier(table_pos.second))
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{
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asof_left_key = right_ast->clone();
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asof_right_key = left_ast->clone();
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analyzed_join.setAsofInequality(ASOF::reverseInequality(inequality));
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}
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else
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{
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throw Exception(ErrorCodes::INVALID_JOIN_ON_EXPRESSION,
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"Expressions {} and {} are from the same table but from different arguments of equal function in ASOF JOIN",
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queryToString(left_ast), queryToString(right_ast));
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}
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}
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void CollectJoinOnKeysMatcher::Data::asofToJoinKeys()
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{
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if (!asof_left_key || !asof_right_key)
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throw Exception("No inequality in ASOF JOIN ON section.", ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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addJoinKeys(asof_left_key, asof_right_key, {JoinIdentifierPos::Left, JoinIdentifierPos::Right});
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}
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void CollectJoinOnKeysMatcher::visit(const ASTIdentifier & ident, const ASTPtr & ast, CollectJoinOnKeysMatcher::Data & data)
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{
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if (auto expr_from_table = getTableForIdentifiers(ast, false, data); expr_from_table != JoinIdentifierPos::Unknown)
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data.analyzed_join.addJoinCondition(ast, isLeftIdentifier(expr_from_table));
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else
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throw Exception("Unexpected identifier '" + ident.name() + "' in JOIN ON section",
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ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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}
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void CollectJoinOnKeysMatcher::visit(const ASTFunction & func, const ASTPtr & ast, Data & data)
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{
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if (func.name == "and")
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return; /// go into children
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ASOF::Inequality inequality = ASOF::getInequality(func.name);
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if (func.name == "equals" || inequality != ASOF::Inequality::None)
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{
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if (func.arguments->children.size() != 2)
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throw Exception("Function " + func.name + " takes two arguments, got '" + func.formatForErrorMessage() + "' instead",
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ErrorCodes::SYNTAX_ERROR);
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}
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if (func.name == "equals")
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{
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ASTPtr left = func.arguments->children.at(0);
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ASTPtr right = func.arguments->children.at(1);
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auto table_numbers = getTableNumbers(left, right, data);
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if (table_numbers.first == table_numbers.second)
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{
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if (table_numbers.first == JoinIdentifierPos::Unknown)
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throw Exception("Ambiguous column in expression '" + queryToString(ast) + "' in JOIN ON section",
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ErrorCodes::AMBIGUOUS_COLUMN_NAME);
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data.analyzed_join.addJoinCondition(ast, isLeftIdentifier(table_numbers.first));
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return;
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}
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if (table_numbers.first != JoinIdentifierPos::NotApplicable && table_numbers.second != JoinIdentifierPos::NotApplicable)
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{
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data.addJoinKeys(left, right, table_numbers);
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return;
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}
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}
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if (auto expr_from_table = getTableForIdentifiers(ast, false, data); expr_from_table != JoinIdentifierPos::Unknown)
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{
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data.analyzed_join.addJoinCondition(ast, isLeftIdentifier(expr_from_table));
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return;
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}
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if (data.is_asof && inequality != ASOF::Inequality::None)
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{
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if (data.asof_left_key || data.asof_right_key)
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throw Exception("ASOF JOIN expects exactly one inequality in ON section. Unexpected '" + queryToString(ast) + "'",
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ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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ASTPtr left = func.arguments->children.at(0);
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ASTPtr right = func.arguments->children.at(1);
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auto table_numbers = getTableNumbers(left, right, data);
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data.addAsofJoinKeys(left, right, table_numbers, inequality);
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return;
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}
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throw Exception("Unsupported JOIN ON conditions. Unexpected '" + queryToString(ast) + "'",
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ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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}
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void CollectJoinOnKeysMatcher::getIdentifiers(const ASTPtr & ast, std::vector<const ASTIdentifier *> & out)
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{
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if (const auto * func = ast->as<ASTFunction>())
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{
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if (func->name == "arrayJoin")
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throw Exception("Not allowed function in JOIN ON. Unexpected '" + queryToString(ast) + "'",
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ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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}
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else if (const auto * ident = ast->as<ASTIdentifier>())
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{
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if (IdentifierSemantic::getColumnName(*ident))
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out.push_back(ident);
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return;
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}
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for (const auto & child : ast->children)
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getIdentifiers(child, out);
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}
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JoinIdentifierPosPair CollectJoinOnKeysMatcher::getTableNumbers(const ASTPtr & left_ast, const ASTPtr & right_ast, Data & data)
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{
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auto left_idents_table = getTableForIdentifiers(left_ast, true, data);
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auto right_idents_table = getTableForIdentifiers(right_ast, true, data);
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return std::make_pair(left_idents_table, right_idents_table);
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}
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const ASTIdentifier * CollectJoinOnKeysMatcher::unrollAliases(const ASTIdentifier * identifier, const Aliases & aliases)
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{
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if (identifier->supposedToBeCompound())
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return identifier;
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UInt32 max_attempts = 100;
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for (auto it = aliases.find(identifier->name()); it != aliases.end();)
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{
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const ASTIdentifier * parent = identifier;
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identifier = it->second->as<ASTIdentifier>();
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if (!identifier)
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break; /// not a column alias
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if (identifier == parent)
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break; /// alias to itself with the same name: 'a as a'
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if (identifier->supposedToBeCompound())
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break; /// not an alias. Break to prevent cycle through short names: 'a as b, t1.b as a'
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it = aliases.find(identifier->name());
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if (!max_attempts--)
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throw Exception("Cannot unroll aliases for '" + identifier->name() + "'", ErrorCodes::LOGICAL_ERROR);
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}
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return identifier;
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}
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/// @returns Left or right table identifiers belongs to.
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/// Place detected identifier into identifiers[0] if any.
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JoinIdentifierPos CollectJoinOnKeysMatcher::getTableForIdentifiers(const ASTPtr & ast, bool throw_on_table_mix, const Data & data)
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{
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std::vector<const ASTIdentifier *> identifiers;
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getIdentifiers(ast, identifiers);
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if (identifiers.empty())
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return JoinIdentifierPos::NotApplicable;
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JoinIdentifierPos table_number = JoinIdentifierPos::Unknown;
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for (auto & ident : identifiers)
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{
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const ASTIdentifier * identifier = unrollAliases(ident, data.aliases);
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if (!identifier)
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continue;
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/// Column name could be cropped to a short form in TranslateQualifiedNamesVisitor.
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/// In this case it saves membership in IdentifierSemantic.
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JoinIdentifierPos membership = JoinIdentifierPos::Unknown;
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if (auto opt = IdentifierSemantic::getMembership(*identifier); opt.has_value())
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{
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if (*opt == 0)
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membership = JoinIdentifierPos::Left;
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else if (*opt == 1)
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membership = JoinIdentifierPos::Right;
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else
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throw DB::Exception(ErrorCodes::AMBIGUOUS_COLUMN_NAME,
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"Position of identifier {} can't be deteminated.",
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identifier->name());
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}
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if (membership == JoinIdentifierPos::Unknown)
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{
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const String & name = identifier->name();
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bool in_left_table = data.left_table.hasColumn(name);
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bool in_right_table = data.right_table.hasColumn(name);
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if (in_left_table && in_right_table)
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{
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/// Relax ambiguous check for multiple JOINs
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if (auto original_name = IdentifierSemantic::uncover(*identifier))
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{
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auto match = IdentifierSemantic::canReferColumnToTable(*original_name, data.right_table.table);
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if (match == IdentifierSemantic::ColumnMatch::NoMatch)
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in_right_table = false;
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in_left_table = !in_right_table;
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}
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else
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throw Exception("Column '" + name + "' is ambiguous", ErrorCodes::AMBIGUOUS_COLUMN_NAME);
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}
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if (in_left_table)
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membership = JoinIdentifierPos::Left;
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if (in_right_table)
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membership = JoinIdentifierPos::Right;
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}
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if (membership != JoinIdentifierPos::Unknown && table_number == JoinIdentifierPos::Unknown)
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{
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table_number = membership;
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std::swap(ident, identifiers[0]); /// move first detected identifier to the first position
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}
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if (membership != JoinIdentifierPos::Unknown && membership != table_number)
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{
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if (throw_on_table_mix)
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throw Exception("Invalid columns in JOIN ON section. Columns "
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+ identifiers[0]->getAliasOrColumnName() + " and " + ident->getAliasOrColumnName()
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+ " are from different tables.", ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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return JoinIdentifierPos::Unknown;
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}
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}
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return table_number;
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}
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}
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