Re: How much do the hint bits help?

On 22/12/10 11:42, Merlin Moncure wrote:
> Attached is an incomplete patch disabling hint bits based on compile
> switch.  It's not complete, for example it's not reconciling some
> assumptions in heapam.c that hint bits have been set in various
> routines.  However, it mostly passes regression and I deemed it good
> enough to run some preliminary benchmarks and fool around.  Obviously,
> hint bits are an annoying impediment to a couple of other cool pending
> features, and it certainly would be nice to operate without them.
> Also, for particular workloads, the extra i/o hint bits can cause a
> fair amount of pain.

Looks like a great idea to test, however I don't seem to be able to 
compile with it applied: (set#define DISABLE_HINT_BITS 1 at the end of 
src/include/pg_config_manual.h)

gcc -O2 -Wall -Wmissing-prototypes -Wpointer-arith 
-Wdeclaration-after-statement -Wendif-labels -fno-strict-aliasing 
-fwrapv -g -I../../../../src/include -D_GNU_SOURCE -c -o heapam.o heapam.c
heapam.c: In function ‘HeapTupleHeaderAdvanceLatestRemovedXid’:
heapam.c:3867: error: ‘HEAP_XMIN_COMMITTED’ undeclared (first use in 
this function)
heapam.c:3867: error: (Each undeclared identifier is reported only once
heapam.c:3867: error: for each function it appears in.)
heapam.c:3869: error: ‘HEAP_XMIN_INVALID’ undeclared (first use in this 
function)
make[4]: *** [heapam.o] Error 1