array_cat(anyarray, anyarray) 连接两个数组,返回新数组 示例:array_cat(ARRAY[1, 2], ARRAY[3, 4]) 结果:{1, 2, 3, 4} array_cat(ARRAY[[1, 2]], ARRAY[3, 4]) 结果:{{1, 2}, {3, 4}} array_cat(ARRAY[[1, 2]], ARRAY[[3, 4]]) 结果:{{1, 2},
估计误差导致慢SQL的常见场景,大致可以分为两类:1)计划的总 cost 估计误差导致慢SQL,2)某些计划节点 rows 估计误差导致慢SQL。 ase 5 这个case 中 t2 只有 3 条数据 ,并且在过滤条件的列上创建了索引,但是优化器基于代价的估计,选择了 Seq Scan,当前这个计划是最快的执行计划。为模拟数据变动,紧接着在 t2...
=equalARRAY[1.1,2.1,3.1]::int[] = ARRAY[1,2,3]t <>not equalARRAY[1,2,3] <> ARRAY[1,2,4]t <less thanARRAY[1,2,3] < ARRAY[1,2,4]t >greater thanARRAY[1,4,3] > ARRAY[1,2,4]t <=less than or equalARRAY[1,2,3] <= ARRAY[1,2,3]t >=greater than or equalARRAY[...
提交消息是: This addscombine, serial and deserial functions for the array_agg() and string_agg()aggregate functions, thus allowing these aggregates to partake in partial aggregations. This allows both parallel aggregation to take place when these aggregates are present and also allows additional p...
(d.encoding)as"Encoding",d.datcollateas"Collate",d.datctypeas"Ctype",pg_catalog.array_to_string(d.datacl,E'\n')AS"Access privileges"FROMpg_catalog.pg_databasedORDERBY1;***ListofdatabasesName|Owner|Encoding|Collate|Ctype|Accessprivileges---+---+---+---+---+---postgres|postgres|UTF...
(2 rows) 1. 2. 3. 4. 5. 6. 使用array_agg函数,如下所示: mydb=> SELECT array_agg(id) FROM test_array3; array_agg --- {{1,2,3},{4,5,6}} (1 row) 1. 2. 3. 4. 5. 也可以将array_agg函数输出类型转换成字符串,并用指定分隔符分隔,使用array_to_string函数,如下所示: mydb...
{ "array_subscript_error", ERRCODE_ARRAY_SUBSCRIPT_ERROR }, { "character_not_in_repertoire", ERRCODE_CHARACTER_NOT_IN_REPERTOIRE }, { "datetime_field_overflow", ERRCODE_DATETIME_FIELD_OVERFLOW }, { "division_by_zero", ERRCODE_DIVISION_BY_ZERO }, { "error_in_assignment", ERRCODE_ERROR_IN...
(9 rows) postgres=# explain (analyze,verbose,timing,costs,buffers) select *fromtbl wheregid=1andc1 && array[1,2,3]; QUERY PLAN --- Bitmap Heap Scan on public.tbl (cost=129.80..3433.25rows=3297width=65) (actualtime=17.453..22.486rows=2932loops=1) Output: gid, c1 Recheck Cond: ((...
[root@EULER1 contrib]# lsadminpack bloom contrib-global.mk dict_xsyn hstore intarray lo oid2name pgcrypto pg_standby pg_visibility sepgsql tablefunc tsm_system_time xml2amcheck btree_gin cube earthdistance hstore_plperl isn ltree pageinspect pg_freespacemap pg_stat_statements postgres_fdw spi...
(4 rows) Time: 0.512 ms postgres=# delete from test1 where id in (select id from (select row_number() over(partition by c1 order by id) as rn, id from test1) t where t.rn<>1); DELETE 998999 Time: 2430.276 ms (00:02.430) ...