• 휴리스틱 기반의 쿼리 변환 : 특정 조건을 충족시키는 경우 적용
• 비용 기반의 쿼리 변환 : 비용 추정기가 산출한 비용에 근거하여, 원래 실행 계획보다 더 낮은 비용의 실행 계획이 생성될 경우 적용

쿼리 변환 - ORDER BY 제거 (휴리스틱 기반)

****************************************
 Cost-Based Group-By/Distinct Placement
****************************************
GBP/DP: Checking validity of GBP/DP for query block SEL$51F12574 (#1)
GBP: Checking validity of group-by placement for query block SEL$51F12574 (#1)
GBP: Bypassed: Query has invalid constructs.
DP: Checking validity of distinct placement for query block SEL$51F12574 (#1)
DP: Bypassed: Query has invalid constructs.
kkqctdrvTD-cleanup: transform(in-use=1592, alloc=4056) :
    call(in-use=2896, alloc=16344), compile(in-use=138984, alloc=153744), execution(in-use=182240, alloc=183416)

kkqctdrvTD-end:
    call(in-use=2896, alloc=16344), compile(in-use=135184, alloc=153744), execution(in-use=182240, alloc=183416)

kkqctdrvTD-start on query block SEL$51F12574 (#1)
kkqctdrvTD-start: :
    call(in-use=2896, alloc=16344), compile(in-use=135184, alloc=153744), execution(in-use=182240, alloc=183416)

TE: Checking validity of table expansion for query block SEL$51F12574 (#1)
TE: Bypassed: No partitioned table in query block.
kkqctdrvTD-cleanup: transform(in-use=0, alloc=0) :
    call(in-use=2896, alloc=16344), compile(in-use=135792, alloc=153744), execution(in-use=182240, alloc=183416)

kkqctdrvTD-end:
    call(in-use=2896, alloc=16344), compile(in-use=136112, alloc=153744), execution(in-use=182240, alloc=183416)

TE: Checking validity of table expansion for query block SEL$51F12574 (#1)
TE: Bypassed: No partitioned table in query block.
ST: Query in kkqstardrv:******* UNPARSED QUERY IS *******
SELECT "T"."N2" "N2",COUNT(*) "COUNT(*)" FROM "CHRIS"."T" "T" GROUP BY "T"."N2"
ST: not valid since star transformation parameter is FALSE
kkqctdrvTD-start on query block SEL$51F12574 (#1)
kkqctdrvTD-start: :
    call(in-use=2896, alloc=16344), compile(in-use=136112, alloc=153744), execution(in-use=182240, alloc=183416)

JF: Checking validity of join factorization for query block SEL$51F12574 (#1)
JF: Bypassed: not a UNION or UNION-ALL query block.
kkqctdrvTD-cleanup: transform(in-use=0, alloc=0) :
    call(in-use=2896, alloc=16344), compile(in-use=136720, alloc=153744), execution(in-use=182240, alloc=183416)

kkqctdrvTD-end:
    call(in-use=2896, alloc=16344), compile(in-use=137040, alloc=153744), execution(in-use=182240, alloc=183416)

JPPD:  Considering Cost-based predicate pushdown from query block SEL$51F12574 (#1)
************************************
Cost-based predicate pushdown (JPPD)
************************************
kkqctdrvTD-start on query block SEL$51F12574 (#1)
kkqctdrvTD-start: :
    call(in-use=2896, alloc=16344), compile(in-use=137040, alloc=153744), execution(in-use=182240, alloc=183416)

kkqctdrvTD-cleanup: transform(in-use=0, alloc=0) :
    call(in-use=2896, alloc=16344), compile(in-use=137648, alloc=153744), execution(in-use=182240, alloc=183416)

kkqctdrvTD-end:
    call(in-use=2896, alloc=16344), compile(in-use=137968, alloc=153744), execution(in-use=182240, alloc=183416)

JPPD: Applying transformation directives
query block SEL$51F12574 (#1) unchanged
FPD: Considering simple filter push in query block SEL$51F12574 (#1)
 ??
Final query after transformations:******* UNPARSED QUERY IS *******
SELECT "T"."N2" "N2",COUNT(*) "COUNT(*)" FROM "CHRIS"."T" "T" GROUP BY "T"."N2"
kkoqbc: optimizing query block SEL$51F12574 (#1)

        :
    call(in-use=2896, alloc=16344), compile(in-use=138936, alloc=153744), execution(in-use=182240, alloc=183416)

kkoqbc-subheap (create addr=0x7f4f408e56d0)
****************
QUERY BLOCK TEXT
****************
SELECT n2, count(*) FROM (SELECT n1, n2 FROM t ORDER BY n1) GROUP BY n2