[ <> ]FORtargetINqueryLOOPstatementsENDLOOP[label]; 3.5 Looping Through Arrays The FOREACH loop iterates through the elements of an array value. The FOREACH statement to loop over an array is: [ <> ] FOREACH target [ SLICE number ]INARRAYexpressionLOOPstatementsENDLOOP[label]; 4.Trapping E...
[ <> ] FOREACH target [ SLICE number ] IN ARRAY expression LOOP statements END LOOP [ label ]; 如果没有指定 SLICE 或者指定 SLICE 0,FOREACH 将会变量数组中的每个元素。例如: DO $$ DECLARE x int; BEGIN FOREACH x IN ARRAY (ARRAY[[1,2,3],[4,5,6]]) LOOP RAISE NOTICE 'x = %',...
其中主节点守护进程主要用来监控本节点数据库服务状态,备节点守护进程主要用来监控主节点和本节点数据库服务状态。在发生Auto Failover时,备节点在尝试N次连接主节点失败后,repmgrd会在所有备节点中选举一个候选备节点(选举机制参考以下Tips)提升为新主节点,然后其他备节点去Follow到该新主上,至此,形成一个新的集群状态...
while 循环条件 loop 循环体语句; 循环控制语句; end loop; FOR 循环 语法: for 循环变量 in [reverse] 集合|查询语句|游标变量 loop 循环体语句; end loop; Select into 语句 语法:select 列名,列名,...into 变量1,变量2,...from 表名 where 条件; 注意:select into 语句查询出的结果只能是一条数据 ...
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) 1. 2. 3. 4. 5. 6. ...
array, descending.SELECTevent, row_numberASindex, rank()OVER (PARTITIONBY(event ->'event_id')::BIGINTORDERBYrow_numberDESC)FROM(-- Use unnest instead of generate_subscripts to turn an array into a set.SELECTevent, row_number()OVER (ORDERBYevent ->'time')FROMunnest(events)ASevent) un...
(key integer) FOR SELECT * FROM tenk1 WHERE unique1 = key; 场景二:超过一个out参数时,把所有的out参数拼成一个row加入datum中 场景三:for loop的targetlist 场景四:into多个变量 PLPGSQL_DTYPE_RECFIELD 场景一:用于record类型中的某一列 PLPGSQL_DTYPE_PROMISE 场景一:trigger会默认创建一些变量用于记录触发...
对表连接支持较完整,MySQL只有一种表连接类型:嵌套循环连接(nested-loop),不支持排序-合并连接(sort-merge join)与散列连接(hash join)。PostgreSQL都支持。 15)存储方式支持更大的数据量 PostgreSQL主表采用堆表存放,MySQL采用索引组织表,能够支持比MySQL更大的数据量。
/* GetNextLocalTransactionId --- allocate a new LocalTransactionId */ LocalTransactionId GetNextLocalTransactionId(void) { LocalTransactionId result; /* loop to avoid returning InvalidLocalTransactionId at wraparound */ do { result = nextLocalTransactionId++; } while (!LocalTransactionIdIsValid(...
FOREACH x in ARRAY v_obj_name LOOP if v_type_name[i] = 'table' then v_new_obj_name := 'md5'||md5(random()::text||clock_timestamp()::text); v_sql[1] := 'alter table '||v_nsp_name[i]||'.'||x||' set schema '||v_new_nsp_name||';'; v_sql[2] := 'alter tab...