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Scenario: 1. The purge thread takes an undo log record and parses it and forms the record to be purged. We have the primary and secondary keys to locate the actual records. 2. Using the secondary index key, we search in the secondary index. One record is found. 3. Then it is checked if this record can be purged. The answer is we can purge this record. To determine this we look up the clustered index record. Either there is no corresponding clustered index record, or the matching clustered index record is delete marked. 4. Then we check whether the secondary index record is delete marked. We find that it is not delete marked. We report warning in optimized build and assert in debug build. Problem: In step 3, we report that the record is purgeable even though it is not delete marked. This is because of inconsistency between the following members of purge_node_t structure - found_clust, ref and pcur. Solution: In the row_purge_reposition_pcur(), if the persistent cursor restore fails, then reset the purge_node_t->found_clust member. This will keep the members of purge_node_t structure in a consistent state. rb#8813 approved by Marko.
129 lines
4.8 KiB
C
129 lines
4.8 KiB
C
/*****************************************************************************
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Copyright (c) 1997, 2015, Oracle and/or its affiliates. All Rights Reserved.
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This program is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free Software
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Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*****************************************************************************/
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/**************************************************//**
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@file include/row0purge.h
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Purge obsolete records
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Created 3/14/1997 Heikki Tuuri
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*******************************************************/
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#ifndef row0purge_h
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#define row0purge_h
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#include "univ.i"
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#include "data0data.h"
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#include "btr0types.h"
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#include "btr0pcur.h"
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#include "dict0types.h"
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#include "trx0types.h"
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#include "que0types.h"
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#include "row0types.h"
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/********************************************************************//**
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Creates a purge node to a query graph.
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@return own: purge node */
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UNIV_INTERN
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purge_node_t*
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row_purge_node_create(
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/*==================*/
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que_thr_t* parent, /*!< in: parent node, i.e., a thr node */
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mem_heap_t* heap); /*!< in: memory heap where created */
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/***********************************************************//**
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Determines if it is possible to remove a secondary index entry.
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Removal is possible if the secondary index entry does not refer to any
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not delete marked version of a clustered index record where DB_TRX_ID
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is newer than the purge view.
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NOTE: This function should only be called by the purge thread, only
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while holding a latch on the leaf page of the secondary index entry
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(or keeping the buffer pool watch on the page). It is possible that
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this function first returns TRUE and then FALSE, if a user transaction
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inserts a record that the secondary index entry would refer to.
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However, in that case, the user transaction would also re-insert the
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secondary index entry after purge has removed it and released the leaf
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page latch.
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@return TRUE if the secondary index record can be purged */
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UNIV_INTERN
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ibool
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row_purge_poss_sec(
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/*===============*/
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purge_node_t* node, /*!< in/out: row purge node */
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dict_index_t* index, /*!< in: secondary index */
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const dtuple_t* entry); /*!< in: secondary index entry */
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/***************************************************************
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Does the purge operation for a single undo log record. This is a high-level
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function used in an SQL execution graph.
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@return query thread to run next or NULL */
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UNIV_INTERN
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que_thr_t*
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row_purge_step(
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/*===========*/
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que_thr_t* thr); /*!< in: query thread */
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/* Purge node structure */
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struct purge_node_struct{
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que_common_t common; /*!< node type: QUE_NODE_PURGE */
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/*----------------------*/
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/* Local storage for this graph node */
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roll_ptr_t roll_ptr;/* roll pointer to undo log record */
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trx_undo_rec_t* undo_rec;/* undo log record */
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trx_undo_inf_t* reservation;/* reservation for the undo log record in
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the purge array */
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undo_no_t undo_no;/* undo number of the record */
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ulint rec_type;/* undo log record type: TRX_UNDO_INSERT_REC,
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... */
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btr_pcur_t pcur; /*!< persistent cursor used in searching the
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clustered index record */
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ibool found_clust;/* TRUE if the clustered index record
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determined by ref was found in the clustered
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index, and we were able to position pcur on
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it */
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dict_table_t* table; /*!< table where purge is done */
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ulint cmpl_info;/* compiler analysis info of an update */
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upd_t* update; /*!< update vector for a clustered index
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record */
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dtuple_t* ref; /*!< NULL, or row reference to the next row to
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handle */
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dtuple_t* row; /*!< NULL, or a copy (also fields copied to
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heap) of the indexed fields of the row to
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handle */
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dict_index_t* index; /*!< NULL, or the next index whose record should
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be handled */
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mem_heap_t* heap; /*!< memory heap used as auxiliary storage for
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row; this must be emptied after a successful
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purge of a row */
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};
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#ifdef UNIV_DEBUG
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/***********************************************************//**
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Validate the persisent cursor in the purge node. The purge node has two
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references to the clustered index record - one via the ref member, and the
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other via the persistent cursor. These two references must match each
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other if the found_clust flag is set.
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@return true if the persistent cursor is consistent with the ref member.*/
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ibool
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row_purge_validate_pcur(purge_node_t* node);
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#endif /* UNIV_DEBUG */
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#ifndef UNIV_NONINL
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#include "row0purge.ic"
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#endif
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#endif
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