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* pg_walfile_name_offset can return inconsistent values
@ 2019-07-26 08:21 Kyotaro Horiguchi <[email protected]>
2019-07-26 09:30 ` Re: pg_walfile_name_offset can return inconsistent values Jehan-Guillaume de Rorthais <[email protected]>
0 siblings, 1 reply; 3+ messages in thread
From: Kyotaro Horiguchi @ 2019-07-26 08:21 UTC (permalink / raw)
To: [email protected]
Hello.
While looking [1], I noticed that pg_walfile_name_offset behaves
somewhat oddly at segment boundary.
select * from (values ('0/16ffffff'), ('0/17000000'), ('0/17000001')) as t(lsn), lateral pg_walfile_name_offset(lsn::pg_lsn);
lsn | file_name | file_offset
------------+--------------------------+-------------
0/16ffffff | 000000020000000000000016 | 16777215
0/17000000 | 000000020000000000000016 | 0
0/17000001 | 000000020000000000000017 | 1
The file names are right as defined, but the return value of the
second line wrong, or at least misleading. It should be (16,
1000000) or (16, FFFFFF). The former is out-of-domain so we would
have no way than choosing the latter. I'm not sure the purpose of
the second output parameter, thus the former might be right
decision.
The function returns the following result after this patch is
applied.
select * from (values ('0/16ffffff'), ('0/17000000'), ('0/17000001')) as t(lsn), lateral pg_walfile_name_offset(lsn::pg_lsn);
lsn | file_name | file_offset
------------+--------------------------+-------------
0/16ffffff | 000000020000000000000016 | 16777214
0/17000000 | 000000020000000000000016 | 16777215
0/17000001 | 000000020000000000000017 | 0
regards.
[1]: https://www.postgresql.org/message-id/20190725193808.1648ddc8@firost
--
Kyotaro Horiguchi
NTT Open Source Software Center
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: pg_walfile_name_offset can return inconsistent values
2019-07-26 08:21 pg_walfile_name_offset can return inconsistent values Kyotaro Horiguchi <[email protected]>
@ 2019-07-26 09:30 ` Jehan-Guillaume de Rorthais <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Jehan-Guillaume de Rorthais @ 2019-07-26 09:30 UTC (permalink / raw)
To: Kyotaro Horiguchi <[email protected]>; +Cc: [email protected]
On Fri, 26 Jul 2019 17:21:20 +0900 (Tokyo Standard Time)
Kyotaro Horiguchi <[email protected]> wrote:
> Hello.
>
> While looking [1], I noticed that pg_walfile_name_offset behaves
> somewhat oddly at segment boundary.
>
> select * from (values ('0/16ffffff'), ('0/17000000'), ('0/17000001')) as
> t(lsn), lateral pg_walfile_name_offset(lsn::pg_lsn);
> lsn | file_name | file_offset
> ------------+--------------------------+-------------
> 0/16ffffff | 000000020000000000000016 | 16777215
> 0/17000000 | 000000020000000000000016 | 0
> 0/17000001 | 000000020000000000000017 | 1
>
>
> The file names are right as defined, but the return value of the
> second line wrong, or at least misleading.
+1
I noticed it as well and put this report on hold while working on my patch.
Thanks for reporting this!
> It should be (16, 1000000) or (16, FFFFFF). The former is out-of-domain so we
> would have no way than choosing the latter. I'm not sure the purpose of
> the second output parameter, thus the former might be right
> decision.
>
> The function returns the following result after this patch is
> applied.
>
> select * from (values ('0/16ffffff'), ('0/17000000'), ('0/17000001')) as
> t(lsn), lateral pg_walfile_name_offset(lsn::pg_lsn);
> lsn | file_name | file_offset
> ------------+--------------------------+-------------
> 0/16ffffff | 000000020000000000000016 | 16777214
> 0/17000000 | 000000020000000000000016 | 16777215
> 0/17000001 | 000000020000000000000017 | 0
So you shift the file offset for all LSN by one byte? This could lead to
regression in various tools relying on this function.
Moreover, it looks weird as the LSN doesn't reflect the given offset anymore
(FFFFFF <> 16777214, 000001 <> 0, etc).
Another solution might be to return the same result when for both 0/16ffffff and
0/17000000, but it doesn't feel right either.
So in fact, returning 0x1000000 seems to be the cleaner result to me.
Regards,
^ permalink raw reply [nested|flat] 3+ messages in thread
* [PATCH 07/16] +nondecimal
@ 2022-12-15 01:04 Justin Pryzby <[email protected]>
0 siblings, 0 replies; 3+ messages in thread
From: Justin Pryzby @ 2022-12-15 01:04 UTC (permalink / raw)
Per Erik Rijkers
---
doc/src/sgml/syntax.sgml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 956182e7c6a..0ccddea310d 100644
--- a/doc/src/sgml/syntax.sgml
+++ b/doc/src/sgml/syntax.sgml
@@ -722,7 +722,7 @@ $function$
<note>
<para>
- Nondecimal integer constants are currently only supported in the range
+ Non-decimal integer constants are currently only supported in the range
of the <type>bigint</type> type (see <xref
linkend="datatype-numeric-table"/>).
</para>
--
2.25.1
--TBNym+cBXeFsS4Vs
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="0008-do-not-end-messages-with-newlines.patch"
^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2022-12-15 01:04 UTC | newest]
Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
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2019-07-26 08:21 pg_walfile_name_offset can return inconsistent values Kyotaro Horiguchi <[email protected]>
2019-07-26 09:30 ` Jehan-Guillaume de Rorthais <[email protected]>
2022-12-15 01:04 [PATCH 07/16] +nondecimal Justin Pryzby <[email protected]>
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