Horton

Re: SUBTRANS: Minimizing calls to SubTransSetParent()

Tomas Vondra <tomas.vondra@enterprisedb.com>

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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: Simon Riggs <simon.riggs@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Julien Tachoires <julmon@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Japin Li <japinli@hotmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org
Date: 2022-11-17T20:29:53Z
Lists: pgsql-hackers 

On 11/17/22 18:29, Simon Riggs wrote:
> On Thu, 17 Nov 2022 at 17:04, Simon Riggs <simon.riggs@enterprisedb.com> wrote:
>>
>> New version with greatly improved comments coming very soon.
> 
>>> Perhaps it would be a good idea to split up the patch.  The business
>>> about making pg_subtrans flat rather than a tree seems like a good
>>> idea in any event, although as I said it doesn't seem like we've got
>>> a fleshed-out version of that here.  We could push forward on getting
>>> that done and then separately consider the rest of it.
>>
>> Yes, I thought you might ask that so, after some thought, have found a
>> clean way to do that and have split this into two parts.
> 
> Attached.
> 
> 002 includes many comment revisions, as well as flattening the loops
> in SubTransGetTopmostTransaction and TransactionIdDidCommit/Abort
> 003 includes the idea to not-always do SubTransSetParent()
> 

I'm a bit confused by the TransactionIdsAreOnSameXactPage naming. Isn't
this really checking clog pages?


regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Used optimized linear search in more code paths

  2. Add subxid-overflow "isolation" test