Reduce the memcpy call from SearchCatCache

Hi,
Here is the oprofile results of pgbench.

CPU: P4 / Xeon with 2 hyper-threads, speed 2793.55 MHz (estimated)
Counted GLOBAL_POWER_EVENTS events
with a unit mask of 0x01 (mandatory) count 100000
samples % app name symbol name
134521 6.8312 ipmi_si (no symbols)
94515 4.7996 vmlinux schedule
52609 2.6716 postgres AllocSetAlloc
39659 2.0140 postgres base_yyparse
34605 1.7573 vmlinux mwait_idle
33234 1.6877 vmlinux _spin_lock
31353 1.5922 libc-2.3.4.so memcpy

I think that the performance improves if the call frequency of memcpy
is reduced. I measured the place where postgres used memcpy.
(Test program is pgbench -t 4000)

total-size avg-size caller
------------------------------------------------------------------------
636185 111968560 176 catcache.c:1129
68236 18436197 270 xlog.c:947
3909 13822874 3536 xlog.c:940
20003 3520528 176 catcache.c:1376
56010 2071477 36 pgstat.c:2288
125524 1902864 15 dynahash.c:948
20001 1760088 88 setrefs.c:205

catcache.c:1129 is memcpy at SearchCatCache, and catcache.c:1376
is memcpy at SearchCatCacheList.

memcpy(cur_skey, cache->cc_skey, sizeof(cur_skey));

Attached patch is reduce the memcpy calls from SearchCatCache
and SearchCatCacheList. This patch directly uses cache->cc_skey
in looking for hash table.
Here is an effect of the patch.

original: Counted GLOBAL_POWER_EVENTS events
samples % app name symbol name
31353 1.5922 libc-2.3.4.so memcpy

patched: Counted GLOBAL_POWER_EVENTS events
samples % app name symbol name
20629 1.0684 libc-2.3.4.so memcpy

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Atsushi Ogawa