postgresql 建立分割槽表，sql優化之postgresql table partitioning
postgresql中使用動態sql-實現自動按時間建立表分割槽
declare
createon varchar(32);
createyy varchar(4);
tablename varchar(48);
i***ist int;
r record;
sqlstr text;
sqldel text;
sqlin text;
begin
//通過以下語句給createon變數賦值
select start_time into createon from tech_trial_t where start_time <>'' order by start_time asc limit 1;
createyy := substr(createon, 1,4);
select count(*) into i***ist from pg_class where relname = 'tech_trial_t_y' || createyy;
if (i***ist=0) then
sqlstr='create table if not exists tech_trial_t_y' || createyy || ' (like tech_trial_t_y2017 including indexes);';
execute sqlstr;
end if;
sqlstr := 'select relname from pg_class where relname like ''tech_trial_t_y20%'' and relname not like ''%_idx'';';
//必須排除索引，因為relname 是**，索引，檢視等的名稱
//for 語句迴圈取值賦值
for r in execute sqlstr loop
sqldel := 'truncate table ' || r.relname;
execute sqldel;
//直接寫 truncate table r.relname; 不能執行，貌似不能知道r.relname是什麼東東。
所以寫成字串語句執行字串語句。
sqlin := 'insert into ' || r.relname || ' select * from tech_trial_t_view_year tv where tv.start_time >= substr( ''' ||r.relname || ''',15,4) ||''-01-01 00:00:00'' and tv.start_time <= substr('''|| r.relname ||''',15,4) ||''-12-31 23:59:59'';';
execute sqlin;
end loop;
return null;
end
declare start_text text;
declare insert_statement text;
begin
start_text := substr(new.start_time, 1 ,4);
insert_statement := 'insert into tech_trial_t_'
|| start_text
||' values ($1.*)';
execute insert_statement using new;
return null;
exception
when undefined_table
then
execute
'create table if not exists tech_trial_t_'
|| start_text
|| '(check (start_time >= '''
|| start_text
|| '-01-01 00:00:00'' and start_time < ''' || start_text || '-12-31 23:59:59'')) inherits (tech_trial_t_year)';
raise notice 'create non-existant table tech_trial_t_year_%', start_text;
execute
'create index tech_trial_t_key_'
|| start_text
|| ' on tech_trial_t_'
|| start_text
|| '(start_time)';
execute insert_statement using new;
return null;
end;
//必須保證每條插入的start_time(分割槽關鍵字）非空。
new表示新插入的記錄
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