The output shows that the total size of the “department_information” table is “8KB”. Example 3: Getting Table Size Using pg_relation_size() Function Alternatively, you can specify the table name inside the “pg_relation_size()” function to get the size of the desired table: SELECTpg...
query1UNION(query2INTERSECTquery3) 排序 SELECT select_listFROMtable_expressionORDERBY sort_expression1[ASC | DESC][NULLS { FIRST | LAST }][, sort_expression2 [ASC | DESC][NULLS { FIRST | LAST }]...] NULLS FIRST 和 NULLS LAST 选项可用于确定在排序顺序中空值是出现在非空值之前还是之后。...
#do# $PGHOME/bin/psql -h ${i} #Clear up temp table t_postgres_table_size_temp ${exe_mysql}--show-warnings -v -v -v -e"truncate t_postgres_table_size_temp;"#Query all postgres instances postgres_instance=`${exe_mysql} -Nse"select concat(instance_hostname,'::',instance_address,'...
pg_stat_statements 模块加载会消耗部分内存，可以通过 pg_stat_statements.max * track_activity_query_size来计算。这个值是比较小的, 假如 pg_stat_statements.max 值为 10000, track_activity_query_size值为4096， 也就消耗了 40 M内存。参数配置如下：shared_preload_libraries = 'pg_stat_statements 'trac...
pg_database_size(pg_database.datname)ASsizeFROMpg_database; In this example, we utilized the pg_database.datname, with the SELECT query to fetch/collect all the databases available in the server. Next, we conjugated them with pg_database_size() and AS SIZE to get the size of all dat...
select pg_relation_size(); select pg_table_size(); select pg_total_relation_size(); 物理、逻辑复制槽: pg_create/drop_physical_replication_slot(slotname); pg_create_logical_replication_slot(slotname,decodingname); pg_logical_slot_get_changes();...
) AS foo ON t.tablename = foo.ctablename AND t.schemaname = foo.schemaname WHERE t.schemaname NOT IN ('pg_catalog', 'information_schema') ORDER BY 1,2; 查询重复索引的脚本 代码语言:javascript 代码运行次数:0 运行 AI代码解释 SELECTpg_size_pretty(sum(pg_relation_size(idx))::bigint)...
PostgreSQL 10 中的并行HashJoin如下图所示,每个子进程都需要扫描右表并构建各自的 HashTable 用于做HashJoin。 PostgreSQL 11 实现了真正的并行HashJoin,所有进程并行扫描右表并构建共享的 HashTable,然后各进程并行扫描左表并执行HashJoin,避免了 PostgreSQL 10 中各自构建一个私有 HashTable 的开销。
*/ uint64 queryId; /* query identifier (can be set by plugins) */ bool canSetTag; /* do I set the command result tag? */ Node *utilityStmt; /* non-null if commandType == CMD_UTILITY */ int resultRelation; /* rtable index of target relation for * INSERT/UPDATE/DELETE; 0 for...
/* dsa_pointer to the page array */ dsa_pointer ptchunks; /* dsa_pointer to the chunk array */ dsa_area *dsa; /* reference to per-query dsa area */};在这个数据结构中，有几个重点需要关注的字段：1.TBMStatus status字段 TBM_EMPTY代表当前TIDBitmap是空TBM_ONE_PAGE 代表...