Re: POC: postgres_fdw insert batching

On 1/21/21 1:17 AM, Zhihong Yu wrote:
> Hi,
> The assignment to resultRelInfo is done when junk_filter_needed is true:
> 
>          if (junk_filter_needed)
>          {
>              resultRelInfo = mtstate->resultRelInfo;
> 
> Should the code for determining batch size access mtstate->resultRelInfo 
> directly ?
> 

IMO the issue is that code iterates over all plans and moves to the next 
for each one:

     resultRelInfo++;

so it ends up pointing past the last element, hence the failures. So 
yeah, either the code needs to move before the loop (per my patch), or 
we need to access mtstate->resultRelInfo directly.

I'm pretty amazed this did not crash during any of the many regression 
runs I did recently.

regards

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