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394 lines
13 KiB
C++
394 lines
13 KiB
C++
#include <Common/typeid_cast.h>
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#include <Columns/ColumnConst.h>
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#include <DataTypes/DataTypesNumber.h>
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#include <Parsers/IAST.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/ASTSelectQuery.h>
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#include <Parsers/ASTExpressionList.h>
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#include <Interpreters/TreeRewriter.h>
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#include <Interpreters/InDepthNodeVisitor.h>
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#include <Interpreters/Context.h>
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#include <IO/WriteBufferFromString.h>
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#include <Storages/transformQueryForExternalDatabase.h>
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#include <Storages/MergeTree/KeyCondition.h>
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#include <Storages/transformQueryForExternalDatabaseAnalyzer.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 LOGICAL_ERROR;
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extern const int INCORRECT_QUERY;
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extern const int UNSUPPORTED_METHOD;
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}
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namespace
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{
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/// Everything except numbers is put as string literal.
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class ReplacingConstantExpressionsMatcherNumOrStr
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{
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public:
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using Data = Block;
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static bool needChildVisit(ASTPtr &, const ASTPtr &)
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{
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return true;
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}
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static void visit(ASTPtr & node, Block & block_with_constants)
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{
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if (!node->as<ASTFunction>())
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return;
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std::string name = node->getColumnName();
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if (block_with_constants.has(name))
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{
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auto result = block_with_constants.getByName(name);
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if (!isColumnConst(*result.column))
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return;
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if (result.column->isNullAt(0))
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{
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node = std::make_shared<ASTLiteral>(Field());
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}
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else if (isNumber(result.type))
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{
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node = std::make_shared<ASTLiteral>(assert_cast<const ColumnConst &>(*result.column).getField());
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}
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else
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{
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/// Everything except numbers is put as string literal. This is important for Date, DateTime, UUID.
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const IColumn & inner_column = assert_cast<const ColumnConst &>(*result.column).getDataColumn();
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WriteBufferFromOwnString out;
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result.type->getDefaultSerialization()->serializeText(inner_column, 0, out, FormatSettings());
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node = std::make_shared<ASTLiteral>(out.str());
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}
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}
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}
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};
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class DropAliasesMatcher
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{
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public:
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struct Data {};
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Data data;
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static bool needChildVisit(ASTPtr &, const ASTPtr &)
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{
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return true;
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}
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static void visit(ASTPtr & node, Data)
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{
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if (!node->tryGetAlias().empty())
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node->setAlias({});
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}
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};
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void replaceConstantExpressions(ASTPtr & node, ContextPtr context, const NamesAndTypesList & all_columns)
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{
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auto syntax_result = TreeRewriter(context).analyze(node, all_columns);
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Block block_with_constants = KeyCondition::getBlockWithConstants(node, syntax_result, context);
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InDepthNodeVisitor<ReplacingConstantExpressionsMatcherNumOrStr, true> visitor(block_with_constants);
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visitor.visit(node);
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}
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void dropAliases(ASTPtr & node)
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{
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DropAliasesMatcher::Data data;
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InDepthNodeVisitor<DropAliasesMatcher, true> visitor(data);
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visitor.visit(node);
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}
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bool isCompatible(ASTPtr & node)
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{
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if (auto * function = node->as<ASTFunction>())
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{
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if (function->parameters) /// Parametric aggregate functions
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return false;
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if (!function->arguments)
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throw Exception(ErrorCodes::LOGICAL_ERROR, "Logical error: function->arguments is not set");
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String name = function->name;
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if (!(name == "and"
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|| name == "or"
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|| name == "not"
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|| name == "equals"
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|| name == "notEquals"
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|| name == "less"
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|| name == "greater"
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|| name == "lessOrEquals"
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|| name == "greaterOrEquals"
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|| name == "like"
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|| name == "notLike"
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|| name == "in"
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|| name == "notIn"
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|| name == "isNull"
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|| name == "isNotNull"
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|| name == "tuple"))
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return false;
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/// A tuple with zero or one elements is represented by a function tuple(x) and is not compatible,
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/// but a normal tuple with more than one element is represented as a parenthesized expression (x, y) and is perfectly compatible.
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/// So to support tuple with zero or one elements we can clear function name to get (x) instead of tuple(x)
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if (name == "tuple")
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{
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if (function->arguments->children.size() <= 1)
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{
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function->name.clear();
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}
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}
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/// If the right hand side of IN is a table identifier (example: x IN table), then it's not compatible.
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if ((name == "in" || name == "notIn")
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&& (function->arguments->children.size() != 2 || function->arguments->children[1]->as<ASTTableIdentifier>()))
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return false;
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for (auto & expr : function->arguments->children)
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if (!isCompatible(expr))
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return false;
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return true;
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}
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if (const auto * literal = node->as<ASTLiteral>())
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{
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if (literal->value.getType() == Field::Types::Tuple)
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{
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/// Represent a tuple with zero or one elements as (x) instead of tuple(x).
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auto tuple_value = literal->value.safeGet<Tuple>();
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if (tuple_value.size() == 1)
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{
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node = makeASTFunction("", std::make_shared<ASTLiteral>(tuple_value[0]));
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return true;
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}
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}
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/// Foreign databases often have no support for Array. But Tuple literals are passed to support IN clause.
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return literal->value.getType() != Field::Types::Array;
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}
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return node->as<ASTIdentifier>();
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}
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bool removeUnknownSubexpressions(ASTPtr & node, const NameSet & known_names);
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void removeUnknownChildren(ASTs & children, const NameSet & known_names)
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{
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ASTs new_children;
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for (auto & child : children)
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{
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bool leave_child = removeUnknownSubexpressions(child, known_names);
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if (leave_child)
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new_children.push_back(child);
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}
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children = std::move(new_children);
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}
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/// return `true` if we should leave node in tree
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bool removeUnknownSubexpressions(ASTPtr & node, const NameSet & known_names)
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{
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if (const auto * ident = node->as<ASTIdentifier>())
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return known_names.contains(ident->name());
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if (node->as<ASTLiteral>() != nullptr)
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return true;
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auto * func = node->as<ASTFunction>();
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if (func && (func->name == "and" || func->name == "or"))
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{
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removeUnknownChildren(func->arguments->children, known_names);
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/// all children removed, current node can be removed too
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if (func->arguments->children.size() == 1)
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{
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/// if only one child left, pull it on top level
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node = func->arguments->children[0];
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return true;
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}
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return !func->arguments->children.empty();
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}
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bool leave_child = true;
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for (auto & child : node->children)
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{
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leave_child = leave_child && removeUnknownSubexpressions(child, known_names);
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if (!leave_child)
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break;
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}
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return leave_child;
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}
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// When a query references an external table such as table from MySQL database,
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// the corresponding table storage has to execute the relevant part of the query. We
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// send the query to the storage as AST. Before that, we have to remove the conditions
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// that reference other tables from `WHERE`, so that the external engine is not confused
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// by the unknown columns.
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bool removeUnknownSubexpressionsFromWhere(ASTPtr & node, const NamesAndTypesList & available_columns)
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{
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if (!node)
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return false;
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NameSet known_names;
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for (const auto & col : available_columns)
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known_names.insert(col.name);
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if (auto * expr_list = node->as<ASTExpressionList>(); expr_list && !expr_list->children.empty())
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{
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/// traverse expression list on top level
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removeUnknownChildren(expr_list->children, known_names);
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return !expr_list->children.empty();
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}
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return removeUnknownSubexpressions(node, known_names);
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}
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String transformQueryForExternalDatabaseImpl(
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ASTPtr clone_query,
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Names used_columns,
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const NamesAndTypesList & available_columns,
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IdentifierQuotingStyle identifier_quoting_style,
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const String & database,
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const String & table,
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ContextPtr context)
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{
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bool strict = context->getSettingsRef().external_table_strict_query;
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auto select = std::make_shared<ASTSelectQuery>();
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select->replaceDatabaseAndTable(database, table);
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auto select_expr_list = std::make_shared<ASTExpressionList>();
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for (const auto & name : used_columns)
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select_expr_list->children.push_back(std::make_shared<ASTIdentifier>(name));
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select->setExpression(ASTSelectQuery::Expression::SELECT, std::move(select_expr_list));
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/** If there was WHERE,
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* copy it to transformed query if it is compatible,
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* or if it is AND expression,
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* copy only compatible parts of it.
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*/
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ASTPtr original_where = clone_query->as<ASTSelectQuery &>().where();
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bool where_has_known_columns = removeUnknownSubexpressionsFromWhere(original_where, available_columns);
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if (original_where && where_has_known_columns)
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{
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replaceConstantExpressions(original_where, context, available_columns);
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if (isCompatible(original_where))
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{
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select->setExpression(ASTSelectQuery::Expression::WHERE, std::move(original_where));
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}
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else if (strict)
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{
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throw Exception(ErrorCodes::INCORRECT_QUERY, "Query contains non-compatible expressions (and external_table_strict_query=true)");
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}
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else if (auto * function = original_where->as<ASTFunction>())
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{
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if (function->name == "and")
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{
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auto new_function_and = makeASTFunction("and");
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for (auto & elem : function->arguments->children)
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{
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if (isCompatible(elem))
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new_function_and->arguments->children.push_back(elem);
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}
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if (new_function_and->arguments->children.size() == 1)
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select->setExpression(ASTSelectQuery::Expression::WHERE, std::move(new_function_and->arguments->children[0]));
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else if (new_function_and->arguments->children.size() > 1)
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select->setExpression(ASTSelectQuery::Expression::WHERE, std::move(new_function_and));
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}
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}
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}
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else if (strict && original_where)
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{
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throw Exception(ErrorCodes::INCORRECT_QUERY, "Query contains non-compatible expressions '{}' (and external_table_strict_query=true)",
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original_where->formatForErrorMessage());
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}
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auto * literal_expr = typeid_cast<ASTLiteral *>(original_where.get());
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UInt64 value;
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if (literal_expr && literal_expr->value.tryGet<UInt64>(value) && (value == 0 || value == 1))
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{
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/// WHERE 1 -> WHERE 1=1, WHERE 0 -> WHERE 1=0.
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if (value)
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original_where = makeASTFunction("equals", std::make_shared<ASTLiteral>(1), std::make_shared<ASTLiteral>(1));
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else
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original_where = makeASTFunction("equals", std::make_shared<ASTLiteral>(1), std::make_shared<ASTLiteral>(0));
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select->setExpression(ASTSelectQuery::Expression::WHERE, std::move(original_where));
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}
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ASTPtr select_ptr = select;
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dropAliases(select_ptr);
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WriteBufferFromOwnString out;
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IAST::FormatSettings settings(out, true);
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settings.identifier_quoting_style = identifier_quoting_style;
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settings.always_quote_identifiers = identifier_quoting_style != IdentifierQuotingStyle::None;
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select->format(settings);
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return out.str();
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}
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}
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String transformQueryForExternalDatabase(
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const SelectQueryInfo & query_info,
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const Names & column_names,
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const NamesAndTypesList & available_columns,
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IdentifierQuotingStyle identifier_quoting_style,
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const String & database,
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const String & table,
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ContextPtr context)
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{
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if (!query_info.syntax_analyzer_result)
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{
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if (!query_info.query_tree)
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throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "Query is not analyzed: no query tree");
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if (!query_info.planner_context)
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throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "Query is not analyzed: no planner context");
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if (!query_info.table_expression)
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throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "Query is not analyzed: no table expression");
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if (column_names.empty())
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throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "No column names for query '{}' to external table '{}.{}'",
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query_info.query_tree->formatASTForErrorMessage(), database, table);
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auto clone_query = getASTForExternalDatabaseFromQueryTree(query_info.query_tree);
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return transformQueryForExternalDatabaseImpl(
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clone_query,
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column_names,
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available_columns,
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identifier_quoting_style,
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database,
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table,
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context);
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}
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auto clone_query = query_info.query->clone();
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return transformQueryForExternalDatabaseImpl(
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clone_query,
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query_info.syntax_analyzer_result->requiredSourceColumns(),
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available_columns,
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identifier_quoting_style,
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database,
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table,
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context);
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}
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}
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