Re: [Proposal] Table-level Transparent Data Encryption (TDE) and KeyManagement Service (KMS)

On Tue, Jul 16, 2019 at 01:24:54PM +0900, Masahiko Sawada wrote:
> On Sat, Jul 13, 2019 at 12:33 AM Bruce Momjian <bruce@momjian.us> wrote:
> > then each row change gets its own LSN.  You are asking if an update that
> > just expires one row and adds it to a new page gets the same LSN.  I
> > don't know.
> 
> The following scripts can reproduce that different two pages have the same LSN.
> 
> =# create table test (a int);
> CREATE TABLE
> =# insert into test select generate_series(1, 226);
> INSERT 0 226
> =# update test set a = a where a = 1;
> UPDATE 1
> =# select lsn from page_header(get_raw_page('test', 0));
>     lsn
> -----------
>  0/1690488
> (1 row)
> 
> =# select lsn from page_header(get_raw_page('test', 1));
>     lsn
> -----------
>  0/1690488
> (1 row)
> 
> So I think it's better to use LSN and page number to create IV. If we
> modify different tables by single WAL we also would need OID or
> relfilenode but I don't think currently we have such operations.

OK, good to know, thanks.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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