BufferPin:表示server process 后台进程等待 buffer pin,手册上解释为 Waiting to acquire a pin on a buffer 官网地址:https://www.postgresql.org/docs/9.6/monitoring-stats.html#WAIT-EVENT-TABLE state :active:表示当前用户正在执行查询等操作;idle:表示当前用户空闲; idle in transaction:表示当前用户在事务中...
|--= 09695 postgres postgres: stats collector process |--= 09697 postgres postgres: postgres sampledb 192.168.1.100(54924) idle --= 09717 postgres postgres: postgres sampledb 192.168.1.100(54964) idle in transaction 内存架构[9] 了解完进程架构后,我们再来了解一下内存架构,PG中的内存主要分为两类:...
stats=(Form_pg_statistic)GETSTRUCT(vardata->statsTuple);//mcv中的选择率,计算同上mcv_selec=mcv_selectivity(vardata,&opproc,constval,true,&sumcommon);hist_selec=ineq_histogram_selectivity(root,...);//直方图的选择率//合并mcv和直方图选择率selec=1.0-stats->stanullfrac-sumcommon;//非高频即直方图...
*/CATALOG(pg_statistic,2619,StatisticRelationId){/* These fields form the unique key for the entry: */Oid starelid;/* relation containing attribute */int16 staattnum;/* attribute (column) stats are for */bool stainherit;/* true if inheritance children are included *//* the fraction of ...
参数“log_statement_stats”控制是否输出所有SQL语句的统计信息,其他的参数控制每个SQL命令是否输出不同执行模块中的统计信息。 3.3 手动收集统计信息 手动收集统计信息的命令是ANALYZE命令,此命令用于收集表的统计信息,然后把结果保存在系统表“pg_statistic”中。优化器可以使用收集到的统计信息来确定最优的执行计划。
(unique1<1000)SELECThistogram_boundsFROMpg_statsWHEREtablename='tenk1'ANDattname='unique1';histogram_bounds---{0,993,1997,3050,4040,5036,5957,7057,8029,9016,9995}selectivity=(1+(1000-bucket[2].min)/(bucket[2].max-bucket[2].min))/num_buckets=(1+(1000-993)/(1997-993))/10=0.100697...
stats collector process logger process autovacuum wal sender/wal receiver 启动流程 main PostmasterMain SysLogger_Start fork_process InitPostmasterChild SysLoggerMain maybe_start_bgworkers ServerLoop StartAutoVacLauncher MaybeStartWalReceiver StartCheckpointer ...
Prints out stats every NSECONDS about all postgresql instances visible on this system. Use CTRL-C to stop. Here's an example run on a postgres database that started idle and then had "pgbench" run against it for 10 seconds: $ pgsqlstat 1 QS QD TxnS TxCm TxAb XLI Sort BufRd BufWd...
Performance counter statsfor'sleep 10': 0 xfs:xfs_attr_list_sf 0 skb:kfree_skb 0 block:block_rq_abort 0 block:block_rq_requeue 0 block:block_rq_complete 0 block:block_rq_insert 0 block:block_rq_issue 0 block:block_bio_bounce
-> BitmapIndexScanontenk1_unique1 (cost=0.00..23.80rows=1007width=0)IndexCond: (unique1 <1000)SELECThistogram_boundsFROMpg_statsWHEREtablename='tenk1'ANDattname='unique1'; histogram_bounds---{0,993,1997,3050,4040,5036,5957,7057,8029,9016,9995} selectivity = (1+ (1000- bucket[2].min...