Обсуждение: How to know detailed information about HOT(Heap-Only Tuples)?
Hi:
And I am searching information for it.
How can I get a detailed information of HOT?
For example:
according to a table, How many tuples are heap only tuples , and how many are not?
And also , Is there any options which can influence HOT occurrance?
Best Regards
On Thu, Aug 22, 2013 at 4:20 AM, 高健 <luckyjackgao@gmail.com> wrote: > according to a table, How many tuples are heap only tuples , and how many > are not? > I believe there are not "hot tuples", a tuple is updated using HOT depending on the indexes defined and the type of update itself. Anyway, you can get an information of how many tuples have been hot-touched via pg_stat_user_tables.n_tup_hot_upd > And also , Is there any options which can influence HOT occurrance? The storage setting (fillfactor) will change the hotness of your tables, but of course this depends on the workload. Luca
On 08/21/2013 07:20 PM, 高健 wrote: > Hi: > > I have heard that Heap-Only Tuples is introduce from 8.3. > And I am searching information for it. > > How can I get a detailed information of HOT? http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/access/heap/README.HOT;hb=HEAD > For example: > according to a table, How many tuples are heap only tuples , and how > many are not? > > And also , Is there any options which can influence HOT occurrance? > > Best Regards -- Adrian Klaver adrian.klaver@gmail.com
Hi:
Thank you all for kindly replying.
I think that I need this: pg_stat_user_tables.n_tup_hot_upd
And Adrian's information is a pretty good material for me to understand the internal.
Best regards
2013/8/22 Adrian Klaver <adrian.klaver@gmail.com>
On 08/21/2013 07:20 PM, 高健 wrote:http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/access/heap/README.HOT;hb=HEADHi:
I have heard that Heap-Only Tuples is introduce from 8.3.
And I am searching information for it.
How can I get a detailed information of HOT?--For example:
according to a table, How many tuples are heap only tuples , and how
many are not?
And also , Is there any options which can influence HOT occurrance?
Best Regards
Adrian Klaver
adrian.klaver@gmail.com