/* * LWLockRelease - release a previously acquired lock */ void LWLockRelease(LWLock *lock) { LWLockMode mode; uint32 oldstate; bool check_waiters; int i; /* * Remove lock from list of locks held. Usually, but not always, it will * be the latest-acquired lock; so search array back...
b.state,b.query,b.xact_start,b.query_start,b.usename,b.datname,b.client_addr,b.client_port,b.application_name from pg_locks a,pg_stat_activity b where a.pid=b.pid and a.granted ), t_overlap as ( select r.* from t_wait w join t_run r on ( r.locktype is not distinct fr...
如果没有持有过该锁,其LOCALLOCK结构体中的nLocks为0,如果能够在本地锁表中找到对应的锁(nLocks不大于零)就说明这个锁对象和锁模式已经授予给本事务,只需要给本地锁表的这个锁增加引用计数就可以,首先增加nLocks计数,增加ResourceOwner中锁的计数。 typedefstructLOCALLOCKTAG{ LOCKTAGlock;/* identifies the lockabl...
* first check for global conflicts: If no locks conflict with my request, * then I get the lock. * * Checking for conflict: lock->grantMask represents the types of * currently held locks. conflictTable[lockmode] has a bit set for each * type of lock that conflicts with request. Bitwi...
2.2 fastpath强锁表FastPathStrongRelationLocks(共享内存) 数据库最常发生的增删改查正常都需要去主锁表中申请常规锁,但是DML操作其实只需要弱锁,且弱锁之间是相容的;所以PG在1-3级锁上做了一层优化:如果事务对某个对象申请弱锁,且对象上没有别人申请的强锁,则可以在会话本地记录弱锁,不走主锁表,不写共享...
PostgreSQL天然集群,多个集群可以组成集簇,有点类似军队的连、团、旅这样的组织规则。对于我们日常学习使用的单节点则是单个集簇单个集群,自己就是集群。 PostgreSQL如何管理这种集群规则?答案是通过一个无符号4个字节的标识进行管理,一个对象就是集群里的一个数据库。
* * Special case: if I find I should go in front of some waiter, check to * see if I conflict with already-held locks or the requests before that * waiter. If not, then just grant myself the requested lock immediately. * This is the same as the test for immediate grant in Lock...
max_connections setting:100max_worker_processes setting:8max_wal_senders setting:10max_prepared_xacts setting:0max_locks_per_xact setting:64track_commit_timestamp setting: off Maximum data alignment:8Database block size:8192Blocks per segment of large relation:131072WAL block size:8192Bytes per WAL...
WALInsertLocks[lockno].l.lastImportantAt = StartPos; 2. ControlFile->checkPoint 共享内存成员ControlFile->checkPoint的更新位于checkpoint skipped代码块之后,在完成checkpoint操作后,会更新ControlFile并进行持久化(写入pg_control文件) ControlFile->checkPoint = ProcLastRecPtr; ...
citus.remote_task_check_interval (integer) 设置Azure Cosmos DB for PostgreSQL 检查任务跟踪器执行程序所管理作业的状态的频率。 默认值为 10 毫秒。 协调器将任务分配给工作器,然后定期在工作器上检查每个任务的进度。 此配置值设置每两次后续检查的时间间隔。 此参数在协调器上生效,可在运行时设置。