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222 lines
8.1 KiB
C++
222 lines
8.1 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/AnalyzedJoin.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 NOT_IMPLEMENTED;
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extern const int LOGICAL_ERROR;
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}
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void CollectJoinOnKeysMatcher::Data::addJoinKeys(const ASTPtr & left_ast, const ASTPtr & right_ast,
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const std::pair<size_t, size_t> & table_no)
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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 (table_no.first == 1 || table_no.second == 2)
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analyzed_join.addOnKeys(left, right);
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else if (table_no.first == 2 || table_no.second == 1)
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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::AMBIGUOUS_COLUMN_NAME);
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has_some = true;
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}
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void CollectJoinOnKeysMatcher::Data::addAsofJoinKeys(const ASTPtr & left_ast, const ASTPtr & right_ast,
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const std::pair<size_t, size_t> & table_no, const ASOF::Inequality & inequality)
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{
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if (table_no.first == 1 || table_no.second == 2)
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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 (table_no.first == 2 || table_no.second == 1)
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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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}
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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, {1, 2});
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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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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(ast, left, right, data);
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data.addJoinKeys(left, right, table_numbers);
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return;
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}
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ASOF::Inequality inequality = ASOF::getInequality(func.name);
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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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throwSyntaxException("ASOF JOIN expects exactly one inequality in ON section, unexpected " + queryToString(ast) + ".");
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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(ast, 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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throwSyntaxException("Expected equals expression, got " + queryToString(ast) + ".");
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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 * 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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std::pair<size_t, size_t> CollectJoinOnKeysMatcher::getTableNumbers(const ASTPtr & expr, const ASTPtr & left_ast, const ASTPtr & right_ast,
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Data & data)
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{
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std::vector<const ASTIdentifier *> left_identifiers;
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std::vector<const ASTIdentifier *> right_identifiers;
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getIdentifiers(left_ast, left_identifiers);
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getIdentifiers(right_ast, right_identifiers);
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size_t left_idents_table = getTableForIdentifiers(left_identifiers, data);
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size_t right_idents_table = getTableForIdentifiers(right_identifiers, data);
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if (left_idents_table && left_idents_table == right_idents_table)
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{
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auto left_name = queryToString(*left_identifiers[0]);
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auto right_name = queryToString(*right_identifiers[0]);
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throwSyntaxException("In expression " + queryToString(expr) + " columns " + left_name + " and " + right_name
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+ " are from the same table but from different arguments of equal function.");
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}
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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->compound())
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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->compound())
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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 1 if identifiers belongs to left table, 2 for right table and 0 if unknown. Throws on table mix.
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/// Place detected identifier into identifiers[0] if any.
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size_t CollectJoinOnKeysMatcher::getTableForIdentifiers(std::vector<const ASTIdentifier *> & identifiers, const Data & data)
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{
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size_t table_number = 0;
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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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auto opt = IdentifierSemantic::getMembership(*identifier);
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size_t membership = opt ? (*opt + 1) : 0;
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if (!membership)
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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 = 1;
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if (in_right_table)
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membership = 2;
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}
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if (membership && table_number == 0)
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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 && membership != table_number)
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{
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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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}
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}
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return table_number;
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}
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[[noreturn]] void CollectJoinOnKeysMatcher::throwSyntaxException(const String & msg)
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{
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throw Exception("Invalid expression for JOIN ON. " + msg +
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" Supported syntax: JOIN ON Expr([table.]column, ...) = Expr([table.]column, ...) "
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"[AND Expr([table.]column, ...) = Expr([table.]column, ...) ...]",
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ErrorCodes::INVALID_JOIN_ON_EXPRESSION);
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}
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}
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