在Postgres(以及任何没有Oracle的数据库)中,NULL不是空字符串,空字符串也不是NULL。 因此,预计会出现此错误: postgres=# do $$ declare x int; begin perform set_config('x.xx', null, false); execute $_$ select current_setting('x.xx', true) $_$ into x; end; $$; ERROR: invalid input s...
SELECTname , settingFROMpg_settingswherename='XXX';SELECTcurrent_setting(name) ;show参数名|showall 4.使配置生效
2、查看参数 show xxx;或select current_setting('xxx'); 3、修改参数 修改当前session的参数配置: set maintenance_work_mem to '128M';或select set_config('maintenance_work_mem','128M',false);ALTER SYSTEM动态修改全局参数: ALTER SYSTEM SET configuration_parameter { TO | = } { value | 'value'...
代价分析Bitmap Index Scan的代价估算就是Index Scan的访问索引数据的代价，即如下计算公式：SELECT round( current_setting('random_page_cost')::real * pages + current_setting('cpu_index_tuple_cost')::real * tuples + current_setting('cpu_operator_cost')::real * tuples) as bitmap_index_s...
SELECT schemaname, relname, n_live_tup, n_dead_tup, last_autovacuumFROM pg_stat_all_tablesORDER BY n_dead_tup / (n_live_tup * current_setting('autovacuum_vacuum_scale_factor')::float8 + current_setting('autovacuum_vacuum_threshold')::float8) DESCLIMIT 10; ...
current_setting --- ISO, YMD (1 row) set_config将参数setting_name设置为new_value。如果is_local设置为true,那么新数值将只应用于当前事务。如果你希望新的数值应用于当前会话,那么应该使用false。它等效于SQL命令SET。比如: MyTest=# SELECT set_config('log_statement_stats','off', false); set_confi...
SELECTname,settingFROMpg_settingsWHEREname='default_transaction_isolation';--或者SELECTcurrent_setting('transaction_isolation'); 修改全局的事务隔离级别: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 ALTERSYSTEMSETdefault_transaction_isolationTO'REPEATABLE READ';--修改之后 reload 实例使之生效SELECTpg_...
(1 row) cpu_cost = cpu_tuple_cost * reltuples xiaoming=# select reltuples, current_setting('cpu_tuple_cost') as cpu_tuple_cost, reltuples * current_setting('cpu_tuple_cost')::real AS cpu_cost from pg_class where relname='t1'; reltuples | cpu_tuple_cost | cpu_cost ---+--...
current_setting(setting_nametext[,missing_okboolean] ) →text 返回设置的setting_name的当前值。 如果没有这样的设置,current_setting将抛出一个错误,除非missing_ok被提供并且为true。 这个函数对应于SQL命令SHOW。 current_setting('datestyle')→ISO, MDY ...
(current_setting('autovacuum_analyze_threshold')::NUMERIC(12,4))+(current_setting('autovacuum_analyze_scale_factor')::NUMERIC(12,4))*reltuples AS 自动分析阈值, (current_setting('autovacuum_vacuum_threshold')::NUMERIC(12,4))+(current_setting('autovacuum_vacuum_scale_factor')::NUMERIC(12,4)...