Re: contrib/cache_scan (Re: What's needed for cache-only table scan?)

Thanks for your testing,

> Getting some compilation warnings while compiling the extension and also
> I am not able to load the extension because of undefined symbol
> "get_restriction_qual_cost".
>

It seems to me you applied only part-1 portion of the custom-scan patches.

The get_restriction_qual_cost() is re-defined as extern function, from
static one, on the part-2 portion (ctidscan) to estimate cost value of the
qualifiers in extension. Also, bms_to_string() and bms_from_string() are
added on the part-3 portion (postgres_fdw) portion to carry a bitmap-set
according to the copyObject manner.

It may make sense to include the above supplemental changes in the cache-
scan feature also, until either of them getting upstreamed.