Re: Release Note Changes - Mailing list pgsql-hackers

Bruce Momjian wrote:
> Simon Riggs wrote:
> 
> [ Sorry for my delay in replying to this.]
> 
>> Few proposals
>>
>> - Can we say "smoothed" rather than "distributed" checkpoints?
>> "Smoothed checkpoints greatly reduce checkpoint I/O spikes"
> 
> Agreed.  Changed.
> 
>> - Heap-Only Tuples (HOT) accelerate space reuse for UPDATEs
>> change to
>> "Heap-Only Tuples (HOT) improve performance of frequent UPDATEs"
> 
> I used the original text because it tries to explain _how_ HOT improves
> performance.  The item that has the descriptive text explains how the
> space reuse works.  A generic "improve performance" doesn't seem like an
> improvement.
> 
>> I also notice that two performance features have disappeared from the
>> release notes. (Presumably they have been removed from source). Both of
>> them have changes that can be seen by users, so can't see why we would
>> want them removed.
>>
>> - Merge Join performance has been substantially improved by ring buffer
>> which avoids materializing the previous sort step. (Simon, Greg)
>>
>> More info, not for release notes:
>> The materialization of the prior sort step would generally double the
>> time taken for the sort, so avoiding this effectively gives a 50%
>> performance gain on sorts that are part of large merge joins.
>>
>>
>> - WAL file switches don't update controlfile any longer. Recovery now
>> refers to the last checkpoint time, which may be many minutes earlier
>> than time previously mentioned. (Simon, Tom)
>>
>> More info, not for release notes:
>> WAL file switches were performed holding important LWLocks, so this
>> improves scalability on high end systems as well as reducing response
>> time spikes under heavy load on all kinds of hardware.
> 
> Let me give you the criteria I use for the release notes.  The release
> notes try to document all changes visible to the average user in a way
> that is understandable to the average user.

hmm I'm not so sure about that - there are a number of changes to psql
that are not mentioned for example - like the addition of various new
backslashcommands (\dF, \dFp, \dFt ,...) as part of the main tsearch2
commit or a number of tab-complete improvements/additions (for tsearch
as well as some other stuff).
While looking at this i noted a "psql's \d command and pg_dump have been
enhanced" in the Object Manipulation Changes" Chapter which looks a bit
missplaced/useless and probably should be removed or clarified and moved
to the psql part.



Stefan