Re: Adding skip scan (including MDAM style range skip scan) to nbtree

On 5/9/25 18:09, Peter Geoghegan wrote:
> On Fri, May 9, 2025 at 11:55 AM Peter Geoghegan <pg@bowt.ie> wrote:
>> Note that "sizeof(FmgrInfo)" is 48 bytes. Prior to skip scan,
>> RelationData.rd_supportinfo would have required 48*5=240 bytes. After
>> skip scan, it would have required 48*6=288 bytes. Maybe 256 bytes is
>> some kind of critical threshold, someplace?
> 
> Can you try it with the attached patch?
> 
> The patch disables skip support entirely, in a way that should
> eliminate whatever the inherent overhead of adding a sixth support
> routine to nbtree was. It does not remove skip scan itself (that
> should still work with queries that are actually eligible to use skip
> scan, albeit slightly less efficiently with some opclasses).
> 

Tried, doesn't seem to affect the results at all.


-- 
Tomas Vondra