[Info-ingres] Fw: tid and the date a row originally came into a table

[Roy Hann]

What is the physical structure of mstests_t_asd?

The low-order nine bits of the TID are the row index within the page.
The high-order bits identify the (partition and) page. The TID in the
example references page 2017.

If it's physical key is mill_roll_id and there is space in page 2017,
that is the page in which the new rows for mill_row_id = 1238198 will
be inserted. It looks like that table accommodates about 100 rows per
page so the page has loads of room.

I don't see anything odd.

Roy

Thursday, May 28, 2020, 4:07:14 PM, you wrote:

>  
> A colleague  has an issue with data being overwritten and some
> inserted by a feed from a plant system. 
>  
> If we look at the table below rows above the cursor may have been
> updated with new results or just be values which were there in 2006. 
>  
> the rows including the cursor row and below didn't have values in
> 2006 and have been inserted on 28-apr-2020  
>  
> The issue is caused by the actual mill roll number recycling in the
> plant system (don't ask why) and the application which fills this
> table and others not realising that this is an old mill roll. 
>  
> The data clearly should be archived off occasionally and there is a
> good reason why this didn't happen.  
>  
> So here is the question -I / we assumed that rows inserted  (after
> 28-apr-2020) would have a recent tuple id but if we look at the table it's clear they don't.
> We are pretty sure that the answer to our question - Is there a way
> of working out when these rows came into the system? - is that there
> isn't but we decided to ask anyway.  It surprised me that the tids were sequential.
>  
> The tuple ids for rows which have genuinely been added recently are
> considerably higher than the ones in this table.  
>  
> BTW a quirk of the plant system means that  not every new mill roll
> after a certain time is a duplicate. In fact very few overlap.  
>  
> If anyone has any ideas ...........  
>  
> thanks 
> Allan & Benoit  
>  


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Roy Hann
Rational Commerce Ltd.
T +44 20 8691 2089
"Ingres development, tuning, and training experts"