Re: Re: Why the lp_len is 28 not 32?

 

From: Tomas Vondra

Date: 2023-02-26 23:07

To: jacktby@gmail.com; pgsql-hackers

Subject: Re: Why the lp_len is 28 not 32?

On 2/26/23 15:35, jacktby@gmail.com wrote:

> use these sqls below:

> create table t(a int);

> insert into t values(1);

> select lp,lp_off,lp_len,t_data from heap_page_items(get_raw_page('t',0));

>  lp | lp_off | lp_len |   t_data   

> ----+--------+--------+------------

>   1 |   8160 |     28 | \x01000000

> --------------------------------------------------------------------------------

 

Pretty sure this is because we align the data to MAXALIGN, and on x86_64

that's 8 bytes. 28 is not a multiple of 8 while 32 is.

 

regards

 

--

Tomas Vondra

EnterpriseDB: http://www.enterprisedb.com

The Enterprise PostgreSQL Company

yes, So it should be 32 bytes not 28bytes, but the sql result is 28 !!!!!! that's false!!!!

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jacktby@gmail.com;