Thanx for the help.
Need some more help.
"table1" has two indices
unique indx1 = "pkfld"
unique indx2 = "fkfld1,fkfld2"
did following steps in the listed order -
1. vacuumed the whole DB
2. "table1"
RecCnt ==> 11970789
Size ==> 2702.41 MB
3.update "table1" set fld7 = 1000 where fld1/1000000 = 999 ;
this UPDATED 1230307 records
4. checked "table1" size again
Reccnt => 11970789
Size ==> 2996.57MB
5. Again did the update, update "table1" set fld7 = 1000 where fld1/1000000
= 999 ;
this UPDATED 1230307 records
6. Got "table1" size as
RecCnt ==> 11970789
Size ==> 3290.64
7. Updated again, update "table1" set fld7 = 1000 where fld1/1000000 = 999 ;
this UPDATED 1230307 records
6. "table1" size as
RecCnt ==> 11970789
Size ==> 3584.66
Found that the size increased gradually. Is HOT working over here ??
Guide me if im doing something wrong.
~ Gauri
On Tue, Apr 29, 2008 at 4:55 PM, Pavan Deolasee <[EMAIL PROTECTED]>
wrote:
> On Tue, Apr 29, 2008 at 4:35 PM, Gauri Kanekar
> <[EMAIL PROTECTED]> wrote:
>
> >
> > Do we need to do any special config changes or any other setting for HOT
> to
> > work??
>
> No. HOT is enabled by default, on all tables. There is no way and need
> to disable it.
>
> >
> > Any special guideline to follow to make HOT working??
> >
>
> You can do couple of things to benefit from HOT.
>
> 1. HOT addresses a special, but common case where UPDATE operation
> does not change any of the index keys. So check if your UPDATE changes
> any of the index keys. If so, see if you can avoid having index
> involving that column. Of course, I won't advocate dropping an index
> if it would drastically impact your frequently run queries.
>
> 2. You may leave some free space in the heap (fillfactor less than
> 100). My recommendation would be to leave space worth of one row or
> slightly more than that to let first UPDATE be an HOT update.
> Subsequent UPDATEs in the page may reuse the dead row created by
> earlier UPDATEs.
>
> 3. Avoid any long running transactions.
>
> Thanks,
> Pavan
>
> --
> Pavan Deolasee
> EnterpriseDB http://www.enterprisedb.com
>
--
Regards
Gauri
