Postgresql-rman

时间 2019-11-10

标签 postgresql rman 栏目 Postgre SQL 繁體版

原文原文链接

联机程序. 而且目标数据库必须处于归档模式。
支持在线全备, 增量备份, 归档备份
- 增量备份基于已经存在的一个全库备份
rman 自己使用pg_start_backup(), copy, pg_stop_backup() 备份模式

自己采用的是文本拷贝… cp/fwrite;node

pg_start_backup()
- text 用户定义的标签, 是备份转储文件将被存储的名字
- boolean 指尽快执行pg_start_backup. 这将会强制一个当即执行的检查点, 会致使I/O操做的峰值, 拖慢任何并发执行的查询.
- boolean 若是为false, 则在完成备份后, pg_stop_backup将当即返回，而无需等待WAL归档
pg_stop_backup()

rman总体架构sql

默认配置参数:shell

PGDATA
BACKUP_PATH
ARCLOG_PATH

pg_rman init数据库

pg_rman showapi

pg_rman config --list架构

pg_rman backup -b full并发

-b inc [incremental]oop

-b arch [archive]ui

pg_rman restorethis

[新增功能] pg_rman blockrecover --datafile tablespaceOid/databaseOid/relfilenode --block 0

备份策略

恢复窗口: 指定天数. 默认值为 7.
备份数量: 冗余度保留。默认值为 1.

代码组织架构:

.
├── backup.c
├── blockrecover.c
├── catalog.c
├── COPYRIGHT
├── data.c
├── delete.c
├── dir.c
├── docs
├── expected
├── idxpagehdr.h
├── init.c
├── Makefile
├── parray.c
├── parray.h
├── pg_rman.c
├── pg_rman.h
├── pgsql_src
├── pgut
├── README.md
├── restore.c
├── script
├── show.c
├── sql
├── util.c
├── validate.c
└── xlog.c

pg_rman-源码浅析

代码阅读

* +----------------+---------------------------------+  
 * | PageHeaderData | linp1 linp2 linp3 ...           |  
 * +-----------+----+---------------------------------+  
 * | ... linpN |                                      |  
 * +-----------+--------------------------------------+  
 * |               ^ pd_lower                         |  
 * |                                                  |  
 * |                     v pd_upper                   |  
 * +-------------+------------------------------------+  
 * |                     | tupleN ...                 |  
 * +-------------+------------------+-----------------+  
 * |       ... tuple3 tuple2 tuple1 | "special space" |  
 * +--------------------------------+-----------------+

若是有数据刷入, 那么将会作持久化，数据库页头部的pd_lsn表示该数据库页最后一次变化时, 变化产生的REDO在wal file中的结束为止.

若是wal flush的lsn插入位置大于或者等于这个pd_lsn将表示这个页的更改是可靠的. 即每次修改都将发生块的变化: 包含LSN的修改.

便可以经过第一次备份开始时的全局LSN, 以及当前须要备份的数据的Page LSN来判断此页是否发生过修改.

修改了即备份，没修改不须要备份, 从而实现数据库的块级别增量备份

增量备份关联代码:

pgBackupGetPath(prev_backup, prev_file_txt, lengthof(prev_file_txt),
                DATABASE_FILE_LIST);
            prev_files = dir_read_file_list(pgdata, prev_file_txt);

            /*
             * Do backup only pages having larger LSN than previous backup.
             */
            lsn = &prev_backup->start_lsn;
            xlogid = (uint32) (*lsn >> 32);
            xrecoff = (uint32) *lsn;
            elog(DEBUG, _("backup only the page updated after LSN(%X/%08X)"),
                            xlogid, xrecoff);

        /* Construct the directory for this backup within BACKUP_PATH. */
        pgBackupGetPath(&current, path, lengthof(path), DATABASE_DIR);

        /* Save the files listed above. */
        backup_files(pgdata, path, files, prev_files, lsn, current.compress_data, NULL);

[新增]块恢复代码:

for (loop = 0; loop <= brc.base_index; loop++)
    {
        backup = (pgBackup *) parray_get(backups, loop);

        /* don't use incomplete nor different timeline backup */
        if (backup->status != BACKUP_STATUS_OK || backup->tli != base_backup->tli)
            continue;
        if(-1 == brc.lastBackupIndex && HAVE_ARCLOG(backup) && brc.last_needed_index >= loop)
        {
            restore_archive_logs(backup,true);
        }
        /* use database backup only */
        if (BACKUP_MODE_INCREMENTAL > backup->backup_mode || brc.last_needed_index < loop)
            continue;

        elog(DEBUG, "found backup BK_KEY: \"%d\" can be used ",backup->backup_id);

        recoverBackup(backup,loop);
        =>  [[
                for(loop = 0; loop < brc.rbNum; loop++)
                {
                    /*If this block has find a page,skip it*/
                    if(brc.pageArray[loop])
                    {
                        elog(DEBUG,"block \'%u\' has find it's page,skip.",brc.recoverBlock[loop]);
                        continue;
                    }
                    page = findPageInBackup(backup, brc.recoverBlock[loop]);
                    if(page)
                    {
                        brc.pageArray[loop] = page;
                        if(-1 == brc.lastBackupIndex)
                        {
                            brc.lastBackupIndex = backupindex;
                            elog(DEBUG,"Find last backup can be used:BK_KEY \'%d\'",backup->backup_id);
                        }
                    }
                }
            ]]
    }

问题:

随意增大filenode大小, 即没法整除8192时, 会默认增大一个Page。此时的Page是不完整的. pg默认不开启checksum校验. 所以Pg会提示blk Num无效, 进行blockrecover操做时, 将会发生没法恢复. 由于整个filenode自己就没有正确的此Page;
当随意修改Page数据时, 有时会发生显示数据不全，即数据条目与插入条目不符的状况. 此时Pg自己没法正常的数据异常告警. 请开启checksum. 进行验证.

checkSum异常告警;

WARNING:  01000: page verification failed, calculated checksum 11654 but expected 8293

肯定table的tuple Num
肯定table的page Num

确保开启checksum功能, 保证Page的数据正常. 但对上述问题不产生有效影响;;

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