teradata - 如何计算 Teradata 数据库中的可用空间

Question

我想报告特定 Teradata 数据库的各种统计数据，尤其是“可用空间”。表倾斜是否应该包括在计算中？例如，有人建议了以下查询:

SELECT databasename
     , SUM(maxperm)/1024/1024/1024 (DECIMAL(10,2))     AS space_allocated
     , SUM(currentperm)/1024/1024/1024 (DECIMAL(10,2)) AS space_Used
     , (MAX(currentperm)*COUNT(*)-SUM(currentperm))
        /1024/1024/1024 (DECIMAL(10, 2)) AS skew_Size

     , (space_used + skew_size) AS total_space_used

     , (MIN(maxperm-currentperm)/1024/1024/1024) * COUNT(*) (DECIMAL(10,2)) 
        AS free_Space

     ,  CAST(total_space_used AS DECIMAL(10,2)) * 100 
      / CAST(space_allocated AS DECIMAL(10,2)) AS pct_used

FROM   DBC.diskspace
WHERE  databasename = 'MyDatabase'
   AND maxperm > 0
GROUP   BY 1;

我特别好奇total_space_used和pct_used的计算。像这样解释倾斜的表格是否“合适”？

Answer 1

绝对要考虑倾斜。您的列 free_space 为您提供了所有已考虑的现有表倾斜的确切可用空间。free_space 还假设所有 future 的表都是完美分布的。不倾斜。