1. 有关Postgresql一些极限值
极限值：
| 最大单个数据库大小 | 不限 | |
| 最大数据单表大小 | 32 TB | |
| 单条记录最大 | 1.6 TB | |
| 单字段最大允许 | 1 GB | |
| 单表允许最大记录数 | 不限 | |
| 单表最大字段数 | 250 - 1600 (取决于字段类型) | |
| 单表最大索引数 | 不限 |
详情阅读：http://www.postgres.cn/about
2. lcoks
URL:http://momjian.us/main/writings/pgsql/internalpics.pdf
见lock.h
/* * These are the valid values of type LOCKMODE for all the standard lock * methods (both DEFAULT and USER). */ /* NoLock is not a lock mode,but a flag value meaning "don't get a lock" */ #define NoLock 0 #define AccessShareLock 1 /* SELECT */ #define RowShareLock 2 /* SELECT FOR UPDATE/FOR SHARE */ #define RowExclusiveLock 3 /* INSERT,UPDATE,DELETE */ #define ShareUpdateExclusiveLock 4 /* VACUUM (non-FULL),ANALYZE,CREATE * INDEX CONCURRENTLY */ #define ShareLock 5 /* CREATE INDEX (WITHOUT CONCURRENTLY) */ #define ShareRowExclusiveLock 6 /* like EXCLUSIVE MODE,but allows ROW * SHARE */ #define ExclusiveLock 7 /* blocks ROW SHARE/SELECT...FOR * UPDATE */ #define AccessExclusiveLock 8 /* ALTER TABLE,DROP TABLE,VACUUM * FULL,and unqualified LOCK TABLE */
3.Postgresql major source code function
4. system tables
:comes from BruceMomjian
5.Offshoots of Postgres
: comes from Bruce Momjian
