postgres=# begin; BEGIN postgres=*# grant select on t3 to u1; ERROR: tuple concurrently deleted postgres=!# rollback ; ROLLBACK postgres=# \errverbose ERROR: XX000: tuple concurrently deleted LOCATION: simple_h
The VACUUM command will reclaim storage space occupied by dead tuples. In normal PostgreSQL operation, tuples that are deleted or obsoleted by an update are not physically removed from their table VACUUM can be run on its own, or with ANALYZE. When the option list is surrounded...
在PostgreSQL中为了消除了冗余索引条目,并允许在不执行table-wide vacuum的情况下重复使用DELETED或废弃的UPDATED元组占用的空间,提出了TheHeap Only Tuple(HOT) 功能。众所周知的,postgresql为了实现读不阻塞写,写不阻塞读使用多版本的方案,即在update和delete元组时并不是直接的删除一行,而是通过xid和标记手段来设置这个...
根据 PostgreSQL 的表锁兼容矩阵: #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 ShareLoc...
Regular maintenance: Run VACUUM and ANALYZE commands regularly to keep statistics up-to-date and reclaim space from deleted rows. Hardware upgrades: Ensure that your hardware resources (CPU, memory, storage) are sufficient to handle your database load. ...
After a successful move operation, shards in the source node get deleted. If the move fails at any point, this function throws an error and leaves the source and target nodes unchanged. Arguments shard_id:ID of the shard to be moved. ...
i.e. the number of tuples present in the table before the processing started. On the other hand,ins,updanddelare the numbers of tuples inserted, updated and deleted by applications during the table processing. (These "concurrent data changes" must also be incorporated into the squeezed table...
=xxxx-- privileges granted to PUBLICr-- SELECT ("read")w-- UPDATE ("write")a-- INSERT ("append")d-- DELETED-- TRUNCATEx-- REFERENCESt-- TRIGGERX-- EXECUTEU-- USAGEC-- CREATEc-- CONNECTT-- TEMPORARYarwdDxt-- ALL PRIVILEGES (for tables, varies for other objects)*-- grant option...
html VACUUM ANALYZE CREATE INDEX CONCURRENTLY CREATE STATISTICS ALTER TABLE CREATE INDEX REFRESH MATERIALIZED VIEW CONCURRENTLY ALTER TABLE DROP TABLE TRUNCATE REINDEX CLUSTER VACUUM FULL REFRESH MATERIALIZED VIEW vacuum的使用除了上述手动执行外,还提供了守护进程autovacuum自动化执行的方式。 2 清理tuple 后面的...
ALTERTABLE[IFEXISTS]nameDETACH PARTITIONpartition_name [CONCURRENTLY| FINALIZE ] 大表search IN ( consts ) 优化 场景: SaaS业务, 电商, 社交等场景 业务特点:IN的输入条件很多导致IN过滤慢 价值: 支持 linear search TO hash table probe,提高IN语句的处理性能, 在条件多、被过滤掉的数据量大的SQL中性能提升...