Re: Performance optimization of btree binary search

On Wed, Dec 4, 2013 at 6:56 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> Hmm.  And yet, there's this:
>
>>  * When a type narrower than Datum is stored in a Datum, we place it in the
>>  * low-order bits and are careful that the DatumGetXXX macro for it discards
>>  * the unused high-order bits (as opposed to, say, assuming they are zero).
>>  * This is needed to support old-style user-defined functions, since depending
>>  * on architecture and compiler, the return value of a function returning char
>>  * or short may contain garbage when called as if it returned Datum.
>
>> And record_image_eq does a rather elaborate dance around here, calling
>> the appropriate GET_x_BYTES macro depending on the type-width.  If we
>> can really count on the high-order bits to be zero, that's all
>> completely unnecessary tomfoolery.
>
> Yeah, that's another thing we could simplify if we fixed this problem
> at the source.  I think these decisions date from a time when we still
> cared about the speed of fmgr_oldstyle.

Sure, let's whack that thing with a crowbar.

-- 
Robert Haas
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