mirror of
https://github.com/ClickHouse/ClickHouse.git
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477 lines
16 KiB
C++
477 lines
16 KiB
C++
#include <Interpreters/evaluateConstantExpression.h>
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#include <Columns/ColumnConst.h>
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#include <Columns/ColumnsNumber.h>
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#include <Core/Block.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <DataTypes/FieldToDataType.h>
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#include <Interpreters/Context.h>
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#include <Interpreters/convertFieldToType.h>
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#include <Interpreters/ExpressionActions.h>
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#include <Interpreters/ExpressionAnalyzer.h>
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#include <Interpreters/TreeRewriter.h>
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#include <Parsers/ASTFunction.h>
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#include <Parsers/ASTIdentifier.h>
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#include <Parsers/ASTLiteral.h>
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#include <Parsers/ASTSubquery.h>
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#include <Parsers/ExpressionElementParsers.h>
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#include <TableFunctions/TableFunctionFactory.h>
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#include <Common/typeid_cast.h>
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#include <Interpreters/FunctionNameNormalizer.h>
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#include <Interpreters/ReplaceQueryParameterVisitor.h>
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#include <Poco/Util/AbstractConfiguration.h>
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#include <unordered_map>
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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 LOGICAL_ERROR;
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extern const int BAD_ARGUMENTS;
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}
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static std::pair<Field, std::shared_ptr<const IDataType>> getFieldAndDataTypeFromLiteral(ASTLiteral * literal)
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{
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auto type = applyVisitor(FieldToDataType(), literal->value);
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/// In case of Array field nested fields can have different types.
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/// Example: Array [1, 2.3] will have 2 fields with types UInt64 and Float64
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/// when result type is Array(Float64).
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/// So, we need to convert this field to the result type.
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Field res = convertFieldToType(literal->value, *type);
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return {res, type};
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}
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std::pair<Field, std::shared_ptr<const IDataType>> evaluateConstantExpression(const ASTPtr & node, const ContextPtr & context)
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{
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if (ASTLiteral * literal = node->as<ASTLiteral>())
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return getFieldAndDataTypeFromLiteral(literal);
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NamesAndTypesList source_columns = {{ "_dummy", std::make_shared<DataTypeUInt8>() }};
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auto ast = node->clone();
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if (ast->as<ASTSubquery>() != nullptr)
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{
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/** For subqueries getColumnName if there are no alias will return __subquery_ + 'hash'.
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* If there is alias getColumnName for subquery will return alias.
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* In result block name of subquery after QueryAliasesVisitor pass will be _subquery1.
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* We specify alias for subquery, because we need to get column from result block.
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*/
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ast->setAlias("constant_expression");
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}
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ReplaceQueryParameterVisitor param_visitor(context->getQueryParameters());
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param_visitor.visit(ast);
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/// Notice: function name normalization is disabled when it's a secondary query, because queries are either
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/// already normalized on initiator node, or not normalized and should remain unnormalized for
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/// compatibility.
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if (context->getClientInfo().query_kind != ClientInfo::QueryKind::SECONDARY_QUERY && context->getSettingsRef().normalize_function_names)
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FunctionNameNormalizer().visit(ast.get());
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auto syntax_result = TreeRewriter(context).analyze(ast, source_columns);
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/// AST potentially could be transformed to literal during TreeRewriter analyze.
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/// For example if we have SQL user defined function that return literal AS subquery.
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if (ASTLiteral * literal = ast->as<ASTLiteral>())
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return getFieldAndDataTypeFromLiteral(literal);
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auto actions = ExpressionAnalyzer(ast, syntax_result, context).getConstActionsDAG();
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ColumnPtr result_column;
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DataTypePtr result_type;
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String result_name = ast->getColumnName();
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for (const auto & action_node : actions->getOutputs())
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{
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if ((action_node->result_name == result_name) && action_node->column)
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{
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result_column = action_node->column;
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result_type = action_node->result_type;
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break;
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}
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}
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if (!result_column)
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throw Exception(ErrorCodes::BAD_ARGUMENTS,
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"Element of set in IN, VALUES or LIMIT or aggregate function parameter "
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"is not a constant expression (result column not found): {}", result_name);
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if (result_column->empty())
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throw Exception(ErrorCodes::LOGICAL_ERROR,
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"Logical error: empty result column after evaluation "
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"of constant expression for IN, VALUES or LIMIT or aggregate function parameter");
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/// Expressions like rand() or now() are not constant
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if (!isColumnConst(*result_column))
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throw Exception(ErrorCodes::BAD_ARGUMENTS,
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"Element of set in IN, VALUES or LIMIT or aggregate function parameter "
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"is not a constant expression (result column is not const): {}", result_name);
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return std::make_pair((*result_column)[0], result_type);
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}
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ASTPtr evaluateConstantExpressionAsLiteral(const ASTPtr & node, const ContextPtr & context)
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{
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/// If it's already a literal.
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if (node->as<ASTLiteral>())
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return node;
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return std::make_shared<ASTLiteral>(evaluateConstantExpression(node, context).first);
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}
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ASTPtr evaluateConstantExpressionOrIdentifierAsLiteral(const ASTPtr & node, const ContextPtr & context)
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{
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if (const auto * id = node->as<ASTIdentifier>())
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return std::make_shared<ASTLiteral>(id->name());
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return evaluateConstantExpressionAsLiteral(node, context);
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}
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ASTPtr evaluateConstantExpressionForDatabaseName(const ASTPtr & node, const ContextPtr & context)
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{
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ASTPtr res = evaluateConstantExpressionOrIdentifierAsLiteral(node, context);
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auto & literal = res->as<ASTLiteral &>();
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if (literal.value.safeGet<String>().empty())
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{
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String current_database = context->getCurrentDatabase();
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if (current_database.empty())
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{
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/// Table was created on older version of ClickHouse and CREATE contains not folded expression.
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/// Current database is not set yet during server startup, so we cannot evaluate it correctly.
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literal.value = context->getConfigRef().getString("default_database", "default");
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}
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else
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literal.value = current_database;
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}
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return res;
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}
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namespace
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{
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using Conjunction = ColumnsWithTypeAndName;
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using Disjunction = std::vector<Conjunction>;
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Disjunction analyzeEquals(const ASTIdentifier * identifier, const Field & value, const ExpressionActionsPtr & expr)
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{
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if (!identifier || value.isNull())
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{
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return {};
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}
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for (const auto & name_and_type : expr->getRequiredColumnsWithTypes())
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{
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const auto & name = name_and_type.name;
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const auto & type = name_and_type.type;
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if (name == identifier->name())
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{
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ColumnWithTypeAndName column;
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Field converted = convertFieldToType(value, *type);
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if (converted.isNull())
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return {};
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column.column = type->createColumnConst(1, converted);
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column.name = name;
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column.type = type;
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return {{std::move(column)}};
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}
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}
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return {};
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}
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Disjunction analyzeEquals(const ASTIdentifier * identifier, const ASTLiteral * literal, const ExpressionActionsPtr & expr)
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{
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if (!identifier || !literal)
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{
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return {};
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}
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return analyzeEquals(identifier, literal->value, expr);
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}
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Disjunction andDNF(const Disjunction & left, const Disjunction & right)
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{
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if (left.empty())
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{
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return right;
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}
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Disjunction result;
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for (const auto & conjunct1 : left)
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{
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for (const auto & conjunct2 : right)
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{
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Conjunction new_conjunct{conjunct1};
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new_conjunct.insert(new_conjunct.end(), conjunct2.begin(), conjunct2.end());
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result.emplace_back(new_conjunct);
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}
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}
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return result;
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}
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Disjunction analyzeFunction(const ASTFunction * fn, const ExpressionActionsPtr & expr, size_t & limit)
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{
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if (!fn || !limit)
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{
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return {};
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}
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// TODO: enumerate all possible function names!
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if (fn->name == "equals")
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{
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const auto * left = fn->arguments->children.front().get();
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const auto * right = fn->arguments->children.back().get();
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const auto * identifier = left->as<ASTIdentifier>() ? left->as<ASTIdentifier>() : right->as<ASTIdentifier>();
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const auto * literal = left->as<ASTLiteral>() ? left->as<ASTLiteral>() : right->as<ASTLiteral>();
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--limit;
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return analyzeEquals(identifier, literal, expr);
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}
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else if (fn->name == "in")
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{
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const auto * left = fn->arguments->children.front().get();
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const auto * right = fn->arguments->children.back().get();
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const auto * identifier = left->as<ASTIdentifier>();
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Disjunction result;
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auto add_dnf = [&](const auto & dnf)
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{
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if (dnf.size() > limit)
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{
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result.clear();
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return false;
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}
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result.insert(result.end(), dnf.begin(), dnf.end());
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limit -= dnf.size();
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return true;
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};
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if (const auto * tuple_func = right->as<ASTFunction>(); tuple_func && tuple_func->name == "tuple")
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{
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const auto * tuple_elements = tuple_func->children.front()->as<ASTExpressionList>();
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for (const auto & child : tuple_elements->children)
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{
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const auto * literal = child->as<ASTLiteral>();
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const auto dnf = analyzeEquals(identifier, literal, expr);
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if (dnf.empty())
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{
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return {};
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}
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if (!add_dnf(dnf))
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{
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return {};
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}
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}
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}
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else if (const auto * tuple_literal = right->as<ASTLiteral>(); tuple_literal)
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{
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if (tuple_literal->value.getType() == Field::Types::Tuple)
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{
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const auto & tuple = tuple_literal->value.get<const Tuple &>();
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for (const auto & child : tuple)
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{
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const auto dnf = analyzeEquals(identifier, child, expr);
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if (dnf.empty())
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{
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return {};
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}
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if (!add_dnf(dnf))
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{
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return {};
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}
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}
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}
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else
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return analyzeEquals(identifier, tuple_literal, expr);
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}
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else
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{
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return {};
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}
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return result;
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}
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else if (fn->name == "or")
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{
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const auto * args = fn->children.front()->as<ASTExpressionList>();
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if (!args)
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{
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return {};
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}
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Disjunction result;
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for (const auto & arg : args->children)
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{
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const auto dnf = analyzeFunction(arg->as<ASTFunction>(), expr, limit);
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if (dnf.empty())
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{
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return {};
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}
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/// limit accounted in analyzeFunction()
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result.insert(result.end(), dnf.begin(), dnf.end());
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}
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return result;
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}
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else if (fn->name == "and")
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{
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const auto * args = fn->children.front()->as<ASTExpressionList>();
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if (!args)
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{
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return {};
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}
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Disjunction result;
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for (const auto & arg : args->children)
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{
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const auto dnf = analyzeFunction(arg->as<ASTFunction>(), expr, limit);
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if (dnf.empty())
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{
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continue;
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}
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/// limit accounted in analyzeFunction()
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result = andDNF(result, dnf);
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}
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return result;
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}
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return {};
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}
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}
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std::optional<Blocks> evaluateExpressionOverConstantCondition(const ASTPtr & node, const ExpressionActionsPtr & target_expr, size_t & limit)
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{
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Blocks result;
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if (const auto * fn = node->as<ASTFunction>())
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{
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std::unordered_map<std::string, bool> always_false_map;
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const auto dnf = analyzeFunction(fn, target_expr, limit);
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if (dnf.empty() || !limit)
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{
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return {};
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}
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auto has_required_columns = [&target_expr](const Block & block) -> bool
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{
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for (const auto & name : target_expr->getRequiredColumns())
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{
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bool has_column = false;
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for (const auto & column_name : block.getNames())
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{
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if (column_name == name)
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{
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has_column = true;
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break;
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}
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}
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if (!has_column)
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return false;
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}
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return true;
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};
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for (const auto & conjunct : dnf)
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{
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Block block;
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for (const auto & elem : conjunct)
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{
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if (!block.has(elem.name))
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{
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block.insert(elem);
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}
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else
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{
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/// Conjunction of condition on column equality to distinct values can never be satisfied.
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const ColumnWithTypeAndName & prev = block.getByName(elem.name);
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if (isColumnConst(*prev.column) && isColumnConst(*elem.column))
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{
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Field prev_value = assert_cast<const ColumnConst &>(*prev.column).getField();
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Field curr_value = assert_cast<const ColumnConst &>(*elem.column).getField();
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if (!always_false_map.contains(elem.name))
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{
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always_false_map[elem.name] = prev_value != curr_value;
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}
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else
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{
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auto & always_false = always_false_map[elem.name];
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/// If at least one of conjunct is not always false, we should preserve this.
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if (always_false)
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{
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always_false = prev_value != curr_value;
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}
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}
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}
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}
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}
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// Block should contain all required columns from `target_expr`
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if (!has_required_columns(block))
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{
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return {};
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}
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target_expr->execute(block);
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if (block.rows() == 1)
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{
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result.push_back(block);
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}
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else if (block.rows() == 0)
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{
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// filter out cases like "WHERE a = 1 AND a = 2"
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continue;
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}
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else
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{
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// FIXME: shouldn't happen
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return {};
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}
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}
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bool any_always_false = std::any_of(always_false_map.begin(), always_false_map.end(), [](const auto & v) { return v.second; });
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if (any_always_false)
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return Blocks{};
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}
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else if (const auto * literal = node->as<ASTLiteral>())
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{
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// Check if it's always true or false.
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if (literal->value.getType() == Field::Types::UInt64 && literal->value.get<UInt64>() == 0)
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return {result};
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else
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return {};
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}
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return {result};
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}
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}
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