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115 lines
3.5 KiB
C++
115 lines
3.5 KiB
C++
#include <Parsers/ASTRenameQuery.h>
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#include <Databases/IDatabase.h>
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#include <Interpreters/Context.h>
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#include <Interpreters/InterpreterRenameQuery.h>
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#include <Storages/IStorage.h>
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#include <Interpreters/DDLWorker.h>
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#include <Common/typeid_cast.h>
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namespace DB
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{
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InterpreterRenameQuery::InterpreterRenameQuery(const ASTPtr & query_ptr_, Context & context_)
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: query_ptr(query_ptr_), context(context_)
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{
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}
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struct RenameDescription
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{
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RenameDescription(const ASTRenameQuery::Element & elem, const String & current_database) :
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from_database_name(elem.from.database.empty() ? current_database : elem.from.database),
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from_table_name(elem.from.table),
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to_database_name(elem.to.database.empty() ? current_database : elem.to.database),
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to_table_name(elem.to.table)
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{}
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String from_database_name;
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String from_table_name;
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String to_database_name;
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String to_table_name;
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};
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BlockIO InterpreterRenameQuery::execute()
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{
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const auto & rename = query_ptr->as<ASTRenameQuery &>();
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if (!rename.cluster.empty())
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{
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NameSet databases;
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for (const auto & elem : rename.elements)
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{
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databases.emplace(elem.from.database);
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databases.emplace(elem.to.database);
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}
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return executeDDLQueryOnCluster(query_ptr, context, std::move(databases));
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}
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String path = context.getPath();
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String current_database = context.getCurrentDatabase();
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/** In case of error while renaming, it is possible that only part of tables was renamed
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* or we will be in inconsistent state. (It is worth to be fixed.)
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*/
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std::vector<RenameDescription> descriptions;
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descriptions.reserve(rename.elements.size());
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/// To avoid deadlocks, we must acquire locks for tables in same order in any different RENAMES.
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struct UniqueTableName
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{
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String database_name;
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String table_name;
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UniqueTableName(const String & database_name_, const String & table_name_)
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: database_name(database_name_), table_name(table_name_) {}
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bool operator< (const UniqueTableName & rhs) const
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{
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return std::tie(database_name, table_name) < std::tie(rhs.database_name, rhs.table_name);
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}
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};
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/// Don't allow to drop tables (that we are renaming); don't allow to create tables in places where tables will be renamed.
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std::map<UniqueTableName, std::unique_ptr<DDLGuard>> table_guards;
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for (const auto & elem : rename.elements)
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{
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descriptions.emplace_back(elem, current_database);
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UniqueTableName from(descriptions.back().from_database_name, descriptions.back().from_table_name);
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UniqueTableName to(descriptions.back().to_database_name, descriptions.back().to_table_name);
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table_guards[from];
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table_guards[to];
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}
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/// Must do it in consistent order.
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for (auto & table_guard : table_guards)
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table_guard.second = context.getDDLGuard(table_guard.first.database_name, table_guard.first.table_name);
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for (auto & elem : descriptions)
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{
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context.assertTableDoesntExist(elem.to_database_name, elem.to_table_name);
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auto from_table = context.getTable(elem.from_database_name, elem.from_table_name);
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auto from_table_lock = from_table->lockExclusively(context.getCurrentQueryId());
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context.getDatabase(elem.from_database_name)->renameTable(
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context,
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elem.from_table_name,
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*context.getDatabase(elem.to_database_name),
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elem.to_table_name,
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from_table_lock);
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}
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return {};
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}
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}
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