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129 lines
4.3 KiB
C++
129 lines
4.3 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 & path, 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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ASTRenameQuery & rename = typeid_cast<ASTRenameQuery &>(*query_ptr);
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if (!rename.cluster.empty())
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return executeDDLQueryOnCluster(query_ptr, context);
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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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std::set<UniqueTableName> unique_tables_from;
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/// Don't allow to drop tables (that we are renaming); do'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, path, 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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unique_tables_from.emplace(from);
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if (!table_guards.count(from))
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table_guards.emplace(from,
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context.getDDLGuard(
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from.database_name,
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from.table_name,
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"Table " + from.database_name + "." + from.table_name + " is being renamed right now"));
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if (!table_guards.count(to))
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table_guards.emplace(to,
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context.getDDLGuard(
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to.database_name,
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to.table_name,
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"Some table right now is being renamed to " + to.database_name + "." + to.table_name));
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}
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std::vector<TableFullWriteLock> locks;
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locks.reserve(unique_tables_from.size());
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for (const auto & names : unique_tables_from)
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if (auto table = context.tryGetTable(names.database_name, names.table_name))
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locks.emplace_back(table->lockForAlter(__PRETTY_FUNCTION__));
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/** All tables are locked. If there are more than one rename in chain,
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* we need to hold global lock while doing all renames. Order matters to avoid deadlocks.
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* It provides atomicity of all RENAME chain as a whole, from the point of view of DBMS client,
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* but only in cases when there was no exceptions during this process and server does not fall.
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*/
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decltype(context.getLock()) lock;
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if (descriptions.size() > 1)
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lock = context.getLock();
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for (const 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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context.getDatabase(elem.from_database_name)->renameTable(
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context, elem.from_table_name, *context.getDatabase(elem.to_database_name), elem.to_table_name);
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}
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return {};
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}
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}
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