See http://www.postgresql.org/docs/current/static/storage-page-layout.html for
all of what is taking up the space. Short version:
Per block overhead is > 24 bytes
Per row overhead is 23 bytes + some alignment loss + the null bitmap if you
have nullable columns
On Mon, Mar 29, 2010 at 8:24 AM, r
Hi Mattew,
Thank you for the information.
Once again, I like to thank each and everyone in this thread for there
ultimate support.
Regards
Raghavendra
On Mon, Mar 29, 2010 at 4:47 PM, Matthew Wakeling wrote:
> On Mon, 29 Mar 2010, Tadipathri Raghu wrote:
>
>> As per the documentation, one page
On Mon, 29 Mar 2010, Tadipathri Raghu wrote:
As per the documentation, one page is 8kb, when i create a table with int as
one column its 4 bytes. If i insert 2000 rows, it should be in one page only
as its 8kb, but its extending vastly as expected. Example shown below,
taking the previous example
Hi Tom,
Thank for the update.
> IIRC, it will set the relpages/reltuples counts (though not any
> more-complex statistics); but only if the table is found to not be
> completely empty. Again, this is a behavior designed with common
> usage patterns in mind, to not set relpages/reltuples to zero
Jeremy Harris writes:
> On 03/28/2010 05:27 PM, Tom Lane wrote:
>> This is intentional: the size estimates for a never-yet-analyzed
>> table are *not* zero. This is because people frequently create and load
>> up a table and then immediately query it without an explicit ANALYZE.
> Does the creat
On 03/28/2010 05:27 PM, Tom Lane wrote:
This is intentional: the size estimates for a never-yet-analyzed
table are *not* zero. This is because people frequently create and load
up a table and then immediately query it without an explicit ANALYZE.
Does the creation of an index also populate s
Tadipathri Raghu writes:
> Frankly speaking its a newly created table without any operation on it as
> you have seen the example. Then how come it showing those many rows where we
> have only one in it.
Yes. This is intentional: the size estimates for a never-yet-analyzed
table are *not* zero.
On 28/03/2010 10:07 AM, Tadipathri Raghu wrote:
Hi All,
I want to give some more light on this by analysing more like this
1. In my example I have created a table with one column as INT( which
occupies 4 bytes)
2. Initially it occupies one page of space on the file that is (8kb).
So, here is i
Op 28 mrt 2010, om 11:07 heeft Tadipathri Raghu het volgende geschreven:
Hi All,
I want to give some more light on this by analysing more like this
1. In my example I have created a table with one column as
INT( which occupies 4 bytes)
2. Initially it occupies one page of space on the fil
Hi All,
I want to give some more light on this by analysing more like this
1. In my example I have created a table with one column as INT( which
occupies 4 bytes)
2. Initially it occupies one page of space on the file that is (8kb).
So, here is it assuming these many rows may fit in this page.
Hi Guz,
> It is assuming that there are 2400 rows in this table. Probably you've
> deleted some rows from the table leaving just one.
Frankly speaking its a newly created table without any operation on it as
you have seen the example. Then how come it showing those many rows where we
have only
2010/3/28 Tadipathri Raghu
> Hi Guz,
>
> Thank you for the prompt reply.
>
>
>> No, the optimizer is not retrieving anything, it just assumes that there
>> are 2400 rows because that is the number of rows that exists in the
>> statictics for this table. The optimizer just tries to find the best p
Hi Guz,
Thank you for the prompt reply.
> No, the optimizer is not retrieving anything, it just assumes that there
> are 2400 rows because that is the number of rows that exists in the
> statictics for this table. The optimizer just tries to find the best plan
> and to optimize the query plan fo
2010/3/28 Tadipathri Raghu
> Hi All,
>
> Example on optimizer
> ===
> postgres=# create table test(id int);
> CREATE TABLE
> postgres=# insert into test VALUES (1);
> INSERT 0 1
> postgres=# select * from test;
> id
>
> 1
> (1 row)
> postgres=# explain select * from test;
>
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