Re: [PROPOSAL] VACUUM Progress Checker.

Hi Vinayak,

Thanks for updating the patch! A quick comment:

On 2016/02/26 17:28, pokurev@pm.nttdata.co.jp wrote:
>> CREATE VIEW pg_stat_vacuum_progress AS
>>   SELECT S.s[1] as pid,
>>          S.s[2] as relid,
>>          CASE S.s[3]
>>            WHEN 1 THEN 'Scanning Heap'
>>            WHEN 2 THEN 'Vacuuming Index and Heap'
>>            ELSE 'Unknown phase'
>>          END,
>>    ....
>>   FROM pg_stat_get_command_progress(PROGRESS_COMMAND_VACUUM) as S;
>>
>> # The name of the function could be other than *_command_progress.
> The name of function is updated as pg_stat_get_progress_info() and also updated the function.
> Updated the pg_stat_vacuum_progress view as suggested.

So, pg_stat_get_progress_info() now accepts a parameter to distinguish
different commands.  I see the following in its definition:

+               /*  Report values for only those backends which are running VACUUM
command */
+               if (cmdtype == COMMAND_LAZY_VACUUM)
+               {
+                       /*Progress can only be viewed by role member.*/
+                       if (has_privs_of_role(GetUserId(), beentry->st_userid))
+                       {
+                               values[2] = UInt32GetDatum(beentry->st_progress_param[0]);
+                               values[3] = UInt32GetDatum(beentry->st_progress_param[1]);
+                               values[4] = UInt32GetDatum(beentry->st_progress_param[2]);
+                               values[5] = UInt32GetDatum(beentry->st_progress_param[3]);
+                               values[6] = UInt32GetDatum(beentry->st_progress_param[4]);
+                               values[7] = UInt32GetDatum(beentry->st_progress_param[5]);
+                               if (beentry->st_progress_param[1] != 0)
+                                       values[8] = Float8GetDatum(beentry->st_progress_param[2] * 100 /
beentry->st_progress_param[1]);
+                               else
+                                       nulls[8] = true;
+                       }
+                       else
+                       {
+                               nulls[2] = true;
+                               nulls[3] = true;
+                               nulls[4] = true;
+                               nulls[5] = true;
+                               nulls[6] = true;
+                               nulls[7] = true;
+                               nulls[8] = true;
+                       }
+               }

How about doing this in a separate function which takes the command id as
parameter and returns an array of values and the number of values (per
command id). pg_stat_get_progress_info() then creates values[] and nulls[]
arrays from that and returns that as result set.  It will be a cleaner
separation of activities, perhaps.