/***************************************************************************** Copyright (c) 1997, 2009, Innobase Oy. All Rights Reserved. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *****************************************************************************/ /**************************************************//** @file include/row0undo.h Row undo Created 1/8/1997 Heikki Tuuri *******************************************************/ #ifndef row0undo_h #define row0undo_h #include "univ.i" #include "mtr0mtr.h" #include "trx0sys.h" #include "btr0types.h" #include "btr0pcur.h" #include "dict0types.h" #include "trx0types.h" #include "que0types.h" #include "row0types.h" /********************************************************************//** Creates a row undo node to a query graph. @return own: undo node */ UNIV_INTERN undo_node_t* row_undo_node_create( /*=================*/ trx_t* trx, /*!< in: transaction */ que_thr_t* parent, /*!< in: parent node, i.e., a thr node */ mem_heap_t* heap); /*!< in: memory heap where created */ /***********************************************************//** Looks for the clustered index record when node has the row reference. The pcur in node is used in the search. If found, stores the row to node, and stores the position of pcur, and detaches it. The pcur must be closed by the caller in any case. @return TRUE if found; NOTE the node->pcur must be closed by the caller, regardless of the return value */ UNIV_INTERN ibool row_undo_search_clust_to_pcur( /*==========================*/ undo_node_t* node); /*!< in: row undo node */ /***********************************************************//** Undoes a row operation in a table. This is a high-level function used in SQL execution graphs. @return query thread to run next or NULL */ UNIV_INTERN que_thr_t* row_undo_step( /*==========*/ que_thr_t* thr); /*!< in: query thread */ /* A single query thread will try to perform the undo for all successive versions of a clustered index record, if the transaction has modified it several times during the execution which is rolled back. It may happen that the task is transferred to another query thread, if the other thread is assigned to handle an undo log record in the chain of different versions of the record, and the other thread happens to get the x-latch to the clustered index record at the right time. If a query thread notices that the clustered index record it is looking for is missing, or the roll ptr field in the record doed not point to the undo log record the thread was assigned to handle, then it gives up the undo task for that undo log record, and fetches the next. This situation can occur just in the case where the transaction modified the same record several times and another thread is currently doing the undo for successive versions of that index record. */ /** Execution state of an undo node */ enum undo_exec { UNDO_NODE_FETCH_NEXT = 1, /*!< we should fetch the next undo log record */ UNDO_NODE_PREV_VERS, /*!< the roll ptr to previous version of a row is stored in node, and undo should be done based on it */ UNDO_NODE_INSERT, /*!< undo a fresh insert of a row to a table */ UNDO_NODE_MODIFY /*!< undo a modify operation (DELETE or UPDATE) on a row of a table */ }; /** Undo node structure */ struct undo_node_struct{ que_common_t common; /*!< node type: QUE_NODE_UNDO */ enum undo_exec state; /*!< node execution state */ trx_t* trx; /*!< trx for which undo is done */ roll_ptr_t roll_ptr;/*!< roll pointer to undo log record */ trx_undo_rec_t* undo_rec;/*!< undo log record */ undo_no_t undo_no;/*!< undo number of the record */ ulint rec_type;/*!< undo log record type: TRX_UNDO_INSERT_REC, ... */ roll_ptr_t new_roll_ptr; /*!< roll ptr to restore to clustered index record */ trx_id_t new_trx_id; /*!< trx id to restore to clustered index record */ btr_pcur_t pcur; /*!< persistent cursor used in searching the clustered index record */ dict_table_t* table; /*!< table where undo is done */ ulint cmpl_info;/*!< compiler analysis of an update */ upd_t* update; /*!< update vector for a clustered index record */ dtuple_t* ref; /*!< row reference to the next row to handle */ dtuple_t* row; /*!< a copy (also fields copied to heap) of the row to handle */ row_ext_t* ext; /*!< NULL, or prefixes of the externally stored columns of the row */ dtuple_t* undo_row;/*!< NULL, or the row after undo */ row_ext_t* undo_ext;/*!< NULL, or prefixes of the externally stored columns of undo_row */ dict_index_t* index; /*!< the next index whose record should be handled */ mem_heap_t* heap; /*!< memory heap used as auxiliary storage for row; this must be emptied after undo is tried on a row */ }; #ifndef UNIV_NONINL #include "row0undo.ic" #endif #endif