接前问,初步学习pg_control文件之十一,再来看下面这个 XLogRecPtr minRecoveryPoint; 看其注释: * minRecoveryPoint is updated to the latest replayed LSN whenever we * flush a data change during archive recovery. That guards against * starting archive recovery, aborting it, and r…
接前文,初步学习pg_control文件之八 来看这个: pg_time_t time; /* time stamp of last pg_control update */ 当初初始化的时候,是这样的: /* * This func must be called ONCE on system install. It creates pg_control * and the initial XLOG segment. */ void BootStrapXLOG(void) { ... Check…
接前文:初步学习pg_control文件之五 ,DB_IN_ARCHIVE_RECOVERY何时出现? 看代码:如果recovery.conf文件存在,则返回 InArchiveRecovery = true. /* * See if there is a recovery command file (recovery.conf), and if so * read in parameters for archive recovery and XLOG streaming. * The file…
接前文 初步学习pg_control文件之四,继续看何时出现 DB_IN_CRASH_RECOVERY: 看下面代码就比较清楚了:如果对 InArchiveRecovery 判断值为假,而且 读取出来pg_control文件的 state不是 SHUTDOWNED状态,表明当初没有来得及把SHUTDOWNED状态写入到pg_control文件,那么就是说系统已经崩溃了. /* * This must be called ONCE during postmaster or standalone-…
接前文,初步学习pg_control文件之三 继续分析 何时出现 DB_SHUTDOWNING状态: 在正常的shutdown的时候,需要进行checkpoint,所以就在此处,设置pg_control文件的state状态为DB_SHUTDOWNING. /* * Perform a checkpoint --- either during shutdown, or on-the-fly * * flags is a bitwise OR of the following: * CHECKPO…
接前文,初步学习pg_control文件之二 继续学习: 研究 DBState,先研究 DB_IN_PRODUCTION ,看它如何出现: 它出现在启动Postmaster时运行的函数处: /* * This must be called ONCE during postmaster or standalone-backend startup */ void StartupXLOG(void) { … /* * Read control file and check XLOG status lo…
初步学习nodejs,业余用node写个一个自动创建目录和文件的小脚本,希望对需要的人有所帮助,如果有bug或者更好的优化方案,也请批评与指正,谢谢,代码如下: var fs = require('fs'); var tel = [ "1/2/4/6/a.tpl.html", "1/2/4/7/9/c.tpl.html", "1/3/5/8/b.tpl.html"]; var demo = function (mulu) { var muluAt…
嘿嘿,说起来ORM和LinQ,就感觉离我好遥远的,在学校是没有学习的,所以总感觉学习了LinQ就是大神,现在嘛,终于也体会一点,感觉LinQ只是初步学习,没有太难,当然以后使用在项目中就没有这样的简单啦,下面就全面的总结一下LinQ的其中一部分,LinQ有三部分:LinQ TO Object:LinQ TO SQL ;LinQ TO XML.而在这里我先来总结一下LinQ TO Object的学习吧 一.初步认识LinQ to Object static void Main(string[] a…
接前文 初步学习pg_control文件之十四 再看如下这个: int MaxConnections; 应该说,它是一个参考值,在global.c中有如下定义 /* * Primary determinants of sizes of shared-memory structures. MaxBackends is * MaxConnections + autovacuum_max_workers + 1 (it is computed by the GUC * assign hooks fo…
接前文 初步学习pg_control文件之十三 看如下几个: /* * Parameter settings that determine if the WAL can be used for archival * or hot standby. */ int wal_level; int MaxConnections; int max_prepared_xacts; int max_locks_per_xact; PostgreSQL中多次用到了函数数组: /* * Method table…
接前文,初步学习pg_control文件之十二 看这个: * backupStartPoint is the redo pointer of the backup start checkpoint, if * we are recovering from an online backup and haven't reached the end of * backup yet. It is reset to zero when the end of backup is reached, and *…
接前文 初步学习pg_control文件之十,再看这个 XLogRecPtr prevCheckPoint; /* previous check point record ptr */ 发生了checkpoint的时候,肯定要处理的: /* * Perform a checkpoint --- either during shutdown, or on-the-fly * * flags is a bitwise OR of the following: * CHECKPOINT_IS_SHU…
接前文 初步学习pg_control文件之九 看下面这个 XLogRecPtr checkPoint; /* last check point record ptr */ 看看这个pointer究竟保留了什么 初始化的时候: /* * This func must be called ONCE on system install. It creates pg_control * and the initial XLOG segment. */ void BootStrapXLOG(void) {…
接前文 初步学习pg_control文件之六 看 pg_control_version 以PostgreSQL9.1.1为了,其HISTORY文件中有如下的内容: Release Release Date: -- This release contains a variety of fixes . For information about new features in the 9.1 major release, see the Section called Release 9.1.…
