Response Time of a query in 2 different enviroment

Question

Hi guys Luca speaking, sorry for the bad written english
the questions is:
The same query on the same table, for definition, number of rows, defined on the same kind of tablespace, the tables are analized
*) I have a query in Benchmark with good results in execution time, the execution plan is really good
*) in Production the execution plan is not so good, the response time isn't comparable (hours vs seconds)
#### The Execution Plan are different ####
#### The stats are the same ####
this a table storico.FLUSSO_ASTCM_INC A with this stats in benchmark
chk Owner Name Partition Subpartition Tablespace NumRows Blocks EmptyBlocks AvgSpace ChainCnt AvgRowLen AvgSpaceFLBlocks NumFLBlocks UserStats GlobalStats LastAnalyzed SampleSize Monitoring Status
True STORICO FLUSSO_ASTCM_INC TBS_DATA 2861719 32025 0 0 0 74 NO YES 10/01/2006 15.53.43 2861719 NO Normal, Successful Completion: 10/01/2006 16.26.05
in Production the stas are the same
the other one is an external_table
the only differences that I noticed at the moment is about the tablespace used to defined the table on:
Production
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 512K
Benchmark
EXTENT MANAGEMENT LOCAL AUTOALLOCATE
I'm studing on at the moment
What I have to check to obtain the same execution plan (without change the query)
This is the query:
SELECT
'test query',
sysdate,
storico.tc_scarti_seq.NEXTVAL,
NULL, --ROW_ID
-- A.AZIONE,
'I',
A.CODE_PREF_TCN,
A.CODE_NUM_TCN,
'ADSL non presente su CRM' ,
-- a.AZIONE
'I'
|| ';' || a.CODE_PREF_TCN
|| ';' || a.CODE_NUM_TCN
|| ';' || a.DATA_ATVZ_CMM
|| ';' || a.CODE_PREF_DSR
|| ';' || a.CODE_NUM_TFN
|| ';' || a.DATA_CSSZ_CMM
|| ';' || a.TIPO_EVENTO
|| ';' || a.INVARIANTE_FONIA
|| ';' || a.CODE_TIPO_ADSL
|| ';' || a.TIPO_RICHIESTA_ATTIVAZIONE
|| ';' || a.TIPO_RICHIESTA_CESSAZIONE
|| ';' || a.ROW_ID_ATTIVAZIONE
|| ';' || a.ROW_ID_CESSAZIONE
FROM storico.FLUSSO_ASTCM_INC A
WHERE NOT EXISTS (SELECT 1 FROM storico.EXT_CRM_X_ADSL B
WHERE A.CODE_PREF_DSR = B.CODE_PREF_DSR
AND A.CODE_NUM_TFN = B.CODE_NUM_TFN
AND A.INVARIANTE_FONIA = B.INVARIANTE_FONIA
AND B.NOME_SERVIZIO NOT IN ('ADSL SMART AGGREGATORE','ADSL SMART TWIN','ALICE IMPRESA TWIN',
'SERVIZIO ADSL PER VIDEOLOTTERY','WI - FI') )
Esito di set autotrace traceonly explain ESERCIZIO
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=144985 Card=143086 B
1 0 SEQUENCE OF 'TC_SCARTI_SEQ'
2 1 FILTER
3 2 TABLE ACCESS (FULL) OF 'FLUSSO_ASTCM_INC' (Cost=1899 C
4 2 EXTERNAL TABLE ACCESS* (FULL) OF 'EXT_CRM_X_ADSL' (Cos :Q370300
4 PARALLEL_TO_SERIAL SELECT /*+ NO_EXPAND FULL(A1) */ A1."CODE_PR
Esito di set autotrace traceonly explain BENCHMARK
Execution Plan
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=3084 Card=2861719 By
tes=291895338)
1 0 SEQUENCE OF 'TC_SCARTI_SEQ'
2 1 HASH JOIN* (ANTI) (Cost=3084 Card=2861719 Bytes=29189533 :Q810002
8)
3 2 TABLE ACCESS* (FULL) OF 'FLUSSO_ASTCM_INC' (Cost=3082 :Q810000
Card=2861719 Bytes=183150016)
4 2 EXTERNAL TABLE ACCESS* (FULL) OF 'EXT_CRM_X_ADSL' (Cos :Q810001
t=2 Card=1 Bytes=38)
2 PARALLEL_TO_SERIAL SELECT /*+ ORDERED NO_EXPAND USE_HASH(A2) US
E_ANTI(A2) */ A1.C0,A1.C1,A1.C2,A1.C
3 PARALLEL_FROM_SERIAL
4 PARALLEL_TO_PARALLEL SELECT /*+ NO_EXPAND FULL(A1) */ A1."CODE_PR
EF_DSR" C0,A1."CODE_NUM_TFN" C1,A1."
The differences on the InitOra are on these parameters:
Could they influence the Optimizer, and the execution plan are so different
background_dump_dest
cpu_count
db_file_multiblock_read_count
db_files
db_32k_cache_size
dml_locks
enqueue_resources
event
fast_start_mttr_target
fast_start_parallel_rollback
hash_area_size
log_buffer
log_parallelism
max_rollback_segments
open_cursors
open_links
parallel_execution_message_size
parallel_max_servers
processes
query_rewrite_enabled
remote_login_passwordfile
session_cached_cursors
sessions
sga_max_size
shared_pool_reserved_size
sort_area_retained_size
sort_area_size
star_transformation_enabled
transactions
undo_retention
user_dump_dest
utl_file_dir
Please Help me
Thanks a lot Luca

Answer 1

Hi Luca,
test and production system are nearly identicall (same OS, same HW Plattform, same software version, same release)
you're using external tables. Are the speed of these drives are identically?
have you analyzed the schema with the same statement? Could you send me the statement?
have you system statistics?
have you testet the statement in an environment which is nearly like the production? concurrent user etc.
Could you send me the top 5 wait events from the statspack report.
Are the data from production and test identical? No data changed. No Index drop? No additional Index? All tables and indexes are analyzed
Regards
Marc