greenplum分區表查看所占空間大小

在使用greenplum數據庫的時候,有的時候想要查看表所占用空間的大小,會使用如下二個函數pg_relation_size和pg_size_pretty.

前者用來查看數據大小,后者是human readable的調整.方法如下:

select pg_size_pretty(pg_relation_size('relation_name')) ;

select pg_size_pretty(pg_relation_size(oid)) ;

但是,對於分區表而言,這個方法就沒有用了,會發現使用后表的大小為0bytes.原因在於:GP的分區表的主表只是一個表定義,其實際數據內容存儲在繼承父表的分區子表里面了.上網查了一下,沒發現有相應的函數,干脆寫了個函數來實現.

 

 
          -- 
           Function: calc_partition_table(character varying, character varying) 
          
 
          
 
          -- 
           DROP FUNCTION calc_partition_table(character varying, character varying); 
          
 
          
 
          CREATE  
          OR  
          REPLACE  
          FUNCTION calc_partition_table(v_schemaname  
          character  
          varying, v_tablename  
          character  
          varying) 
          
   
          RETURNS  
          bigint  
          AS 
          
$BODY$ 
          
 
          DECLARE 
          
    v_calc  
          BIGINT : 
          =  
          0; 
          
    v_total  
          BIGINT : 
          =  
          0; 
          
    v_tbname  
          VARCHAR( 
          200); 
          
    cur_tbname  
          cursor  
          for  
          select schemaname 
          || 
          ' 
          . 
          ' 
          ||partitiontablename  
          as tb  
          from pg_partitions 
          
    
          where schemaname 
          =v_schemaname  
          and tablename 
          =v_tablename; 
          
 
          BEGIN 
          
     
          OPEN cur_tbname; 
          
    loop 
          
         
          FETCH cur_tbname  
          into v_tbname; 
          
         
          if  
          not found  
          THEN 
          
             
          exit; 
          
         
          end  
          if; 
          
         
          EXECUTE  
          ' 
          select pg_relation_size( 
          ''' 
          ||v_tbname 
          || 
          ''' 
          ) 
          '  
          into v_calc; 
          
        v_total: 
          =v_total 
          +v_calc;         
          
     
          end loop; 
          
     
          CLOSE cur_tbname; 
          
     
          RETURN v_total; 
          
 
          end; 
          
$BODY$ 
          
  LANGUAGE plpgsql VOLATILE; 
          
 
          ALTER  
          FUNCTION calc_partition_table( 
          character  
          varying,  
          character  
          varying) OWNER  
          TO gpadmin;