Re: Abbreviated keys for Numeric

On Sun, Mar 22, 2015 at 1:01 PM, Andrew Gierth
<andrew(at)tao11(dot)riddles(dot)org(dot)uk> wrote:
> So here's a version 3 patch:

By the way, there was another bug in this that I forgot to point out,
but removed, here:

+ if (nss->estimating)
+ {
+ uint32 tmp = (uint32)result;
+ addHyperLogLog(&nss->abbr_card, hash_uint32(tmp));
+ }

And here:

+ if (nss->estimating)
+ {
+ uint32 tmp = ((uint32)result) ^ (uint32)((uint64) result >> 32);
+ addHyperLogLog(&nss->abbr_card, hash_uint32(tmp));
+ }

(I simply operate on the raw Datum when hashing for hyperLogLog, in a
similar manner to the text opclass, which is safe with 8 byte datums +
pass by value int64).

The problem here is that you're not calling hash_uint32() through
DatumGetUInt32() - hash_uint32() returns Datum. And yes, that matters
- see commit 2c22afaa.

You also need to indent this code correctly.

--
Peter Geoghegan