Monday, May 7, 2012 The Lambda Calculus for Absolute Dummies (like myself) If there is one highly underrated concept in philosophy today, it is computation. Why is it so important? Because computationalism is the new mechanism. For millennia, philo…
WAL是SQLite3.7.0版本引入的一个重大改进.SQLite官网宣称在很多使用场景下,WAL模型的性能都要好于默认的DELETE模式.下面将针对几个主要场景对WAL性能做测试,测试的硬件与xxx保持一致. 纯写场景 1) 测试说明 测试简单更新事务在WAL模式下与DELETE日志模式性能对比,测试语句形如:update user set c1=c1+1 where id=xxx,id为主键,串行执行更新.通过执行1w个更新事务,统计程序运行时间. 2) 测试结果 测试时间结果以毫秒计算…
标注:本文部分有黏贴这里的资料,另外还加了一些自己的笔记 使用CoreData或者SQLite3的时候,我们创建的数据库, 在存储的文件夹中有三个文件:分别为:**.sqlite **.sqlite-shm **.sqlie-wal http://www.sqlite.org/fileformat2.html SQLite官方对数据库文件格式的文档 文档开头写了: During a transaction, SQLite stores additional information in a…
WAL record format typedef struct XLogRecord{pg_crc32 xl_crc; /* CRC for this record */XLogRecPtr xl_prev; /* ptr to previous record in log */TransactionId xl_xid; /* xact id */uint32 xl_tot_len; /* total len of entire reco…
Jeff Janes: Hi, As part of our monitoring work for our customers, we stumbled upon an issue with our customers' servers who have a wal_keep_segments setting higher than 0. We have a monitoring script that checks the number of WAL files in the pg_xlog…
Guillaume Lelarge: Hi, As part of our monitoring work for our customers, we stumbled upon an issue with our customers' servers who have a wal_keep_segments setting higher than 0. We have a monitoring script that checks the number of WAL files in th…
