We have a problem with the oracle optimizer at oracle 12c. It takes several executions of a sql statement until the sql is marked as IS_REOPTIMIZABLE=N.
Following output of the same statement and nearly the same data at oracle11g/oracle12c.
-- output of v$sql (oracle 12c)
SQL_ID CHILD_NUMBER IS_REOPTIMIZABLE IS_BIND_SENSITIVE ELAPSED_TIME IS_BIND_AWARE IS_SHAREABLE IS_OBSOLETE FETCHES EXECUTIONS OPTIMIZER_COST SQL_PLAN_BASELINE
0f83zdknhqsmj 1 Y N 12575247 N N N 1 1 35 SQL_PLAN_3b0ugvyu8w97a4132b007
0f83zdknhqsmj 2 Y N 78337268 N N N 1 1 35 SQL_PLAN_3b0ugvyu8w97a4132b007
0f83zdknhqsmj 3 Y N 6079189 N N N 1 1 35 SQL_PLAN_3b0ugvyu8w97a4132b007
0f83zdknhqsmj 4 Y N 6162748 N N N 1 1 35 SQL_PLAN_3b0ugvyu8w97a4132b007
0f83zdknhqsmj 5 Y N 6647007 N N N 1 1 35 SQL_PLAN_3b0ugvyu8w97a4132b007
0f83zdknhqsmj 6 N N 6939813 N Y N 3 3 35 SQL_PLAN_3b0ugvyu8w97a4132b007
-- output of v$sql (oracle 11g)
SQL_ID CHILD_NUMBER IS_BIND_SENSITIVE ELAPSED_TIME IS_BIND_AWARE IS_SHAREABLE IS_OBSOLETE FETCHES EXECUTIONS OPTIMIZER_COST SQL_PLAN_BASELINE
0f83zdknhqsmj 0 N 2630792 N Y N 2 2 35 SQL_PLAN_3b0ugvyu8w97a4132b007
As you can see
the elapsed time is quite bad on oracle 12c. Finally the execution plan of the baseline is always used, this plan is good enough. If the cursor is reused (execution>=7), the elapsed time is about 0,25 seconds
on oracle 11g the cursor is reused immediatly , on oracle 12c the optimizer needs 6 tries until it reuses the cursor and the elapsed time is acceptable. After a short while the optimizer retries to optimize the sql.
So the question is:
How can we force the optimizer to reuse the sql cursor and reduce its effort for reoptimization?
Here are some maybe necessary informations, if you need more let me know.
Thanks in advance!
-- optimization hints
select v.CHILD_NUMBER, v.HINT_ID, v.HINT_TEXT from V$SQL_REOPTIMIZATION_HINTS v where v.SQL_ID = '0f83zdknhqsmj';
CHILD_NUMBER HINT_ID HINT_TEXT
5 1 OPT_ESTIMATE (#"SEL$8" TABLE "HEFTFOLGE"#"SEL$8" MIN=132.000000 )
5 2 OPT_ESTIMATE (#"SEL$8" INDEX_FILTER "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=132.000000 )
5 3 OPT_ESTIMATE (#"SEL$8" INDEX_SCAN "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=132.000000 )
4 1 OPT_ESTIMATE (#"SEL$8" TABLE "HEFTFOLGE"#"SEL$8" MIN=578.000000 )
4 2 OPT_ESTIMATE (#"SEL$8" INDEX_FILTER "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=578.000000 )
4 3 OPT_ESTIMATE (#"SEL$8" INDEX_SCAN "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=578.000000 )
3 1 OPT_ESTIMATE (#"SEL$8" TABLE "HEFTFOLGE"#"SEL$8" MIN=75.000000 )
3 2 OPT_ESTIMATE (#"SEL$8" INDEX_FILTER "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=76.000000 )
3 3 OPT_ESTIMATE (#"SEL$8" INDEX_SCAN "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=76.000000 )
2 1 OPT_ESTIMATE (#"SEL$8" TABLE "HEFTFOLGE"#"SEL$8" MIN=730.000000 )
2 2 OPT_ESTIMATE (#"SEL$8" INDEX_FILTER "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=730.000000 )
2 3 OPT_ESTIMATE (#"SEL$8" INDEX_SCAN "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=730.000000 )
1 1 OPT_ESTIMATE (#"SEL$8" TABLE "HEFTFOLGE"#"SEL$8" MIN=1644.000000 )
1 2 OPT_ESTIMATE (#"SEL$8" INDEX_FILTER "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=1644.000000 )
1 3 OPT_ESTIMATE (#"SEL$8" INDEX_SCAN "HEFTFOLGE"#"SEL$8" "PS_CS_HEFTFOLGE_TB" MIN=1644.000000 )
-- Optimizer settings
NAME VALUE
plsql_optimize_level 2
optimizer_features_enable 12.1.0.2
optimizer_mode ALL_ROWS
_optimizer_max_permutations 50
optimizer_index_cost_adj 20
optimizer_index_caching 0
optimizer_dynamic_sampling 4
optimizer_secure_view_merging TRUE
optimizer_use_pending_statistics FALSE
optimizer_capture_sql_plan_baselines FALSE
optimizer_use_sql_plan_baselines TRUE
optimizer_use_invisible_indexes FALSE
optimizer_adaptive_reporting_only FALSE
optimizer_adaptive_features TRUE
optimizer_inmemory_aware TRUE
-- Execution plan
SQL_ID 0f83zdknhqsmj, child number 6
-------------------------------------
SELECT CS_AUFTRAG_ID, CS_AUFPOS_SEQ, CS_AUFLIEF_SEQ, CS_AUFUNT_SEQ,
CS_AUFUNT_SEQ_BEFR, CS_HEFTFOLGE_ID, SEQNO, CS_HEFTFOLGE,
TO_CHAR(ACTUAL_PUB_DATE,'YYYY-MM-DD'),
TO_CHAR(CS_VSSOLL_DT,'YYYY-MM-DD'), TO_CHAR(CS_VSIST_DT,'YYYY-MM-DD'),
CS_ANZAHL_GEL, CS_MINLIEF, CS_YESNO_WV, CS_YESNO_LIEFERN,
CS_BEFRIST_CD, CS_UNTERBR_CD, CS_UDGRUND_CD, CS_YESNO_LIEFEINST,
CS_VERSART_CD, CS_KONDITION, CS_LIEFERMENGE, CS_PREIS, CURRENCY_CD,
CS_YESNO_TERMADR, CS_KDNR_AS400, CS_ADR_LINE_1, CS_YESNO_NACHLIEF,
TO_CHAR(CS_VSIST2_DT,'YYYY-MM-DD'), CS_ZUSTELLTYP_CD, CS_YN_HORIZONT
FROM PS_CS_HEFTEREIT_VW WHERE CS_AUFTRAG_ID=:1 AND CS_AUFPOS_SEQ=:2 AND
CS_AUFLIEF_SEQ=:3 ORDER BY CS_AUFTRAG_ID, CS_AUFPOS_SEQ,
CS_AUFLIEF_SEQ, SEQNO
Plan hash value: 4191856942
-----------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | | | 35 (100)| |
| 1 | SORT AGGREGATE | | 1 | 43 | | |
|* 2 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFLIEF_AU | 1 | 43 | 1 (0)| 00:00:01 |
|* 3 | INDEX RANGE SCAN | PSACS_AUFLIEF_AU | 1 | | 1 (0)| 00:00:01 |
| 4 | SORT ORDER BY | | 1 | 916 | 35 (9)| 00:00:01 |
|* 5 | FILTER | | | | | |
| 6 | NESTED LOOPS OUTER | | 1 | 916 | 31 (7)| 00:00:01 |
| 7 | NESTED LOOPS OUTER | | 1 | 866 | 30 (7)| 00:00:01 |
| 8 | NESTED LOOPS OUTER | | 1 | 798 | 29 (7)| 00:00:01 |
| 9 | NESTED LOOPS | | 1 | 708 | 28 (8)| 00:00:01 |
| 10 | NESTED LOOPS | | 1 | 640 | 27 (8)| 00:00:01 |
| 11 | NESTED LOOPS OUTER | | 1 | 550 | 26 (8)| 00:00:01 |
| 12 | NESTED LOOPS OUTER | | 1 | 512 | 25 (8)| 00:00:01 |
| 13 | NESTED LOOPS OUTER | | 1 | 469 | 24 (9)| 00:00:01 |
| 14 | NESTED LOOPS OUTER | | 1 | 411 | 23 (9)| 00:00:01 |
| 15 | VIEW | | 1 | 346 | 22 (10)| 00:00:01 |
| 16 | NESTED LOOPS OUTER | | 1 | 443 | 22 (10)| 00:00:01 |
|* 17 | VIEW | | 1 | 386 | 21 (10)| 00:00:01 |
| 18 | WINDOW SORT | | 1 | 540 | 21 (10)| 00:00:01 |
| 19 | NESTED LOOPS OUTER | | 1 | 540 | 20 (5)| 00:00:01 |
| 20 | NESTED LOOPS OUTER | | 1 | 488 | 19 (6)| 00:00:01 |
| 21 | NESTED LOOPS OUTER | | 1 | 424 | 18 (6)| 00:00:01 |
| 22 | NESTED LOOPS OUTER | | 1 | 374 | 17 (6)| 00:00:01 |
| 23 | NESTED LOOPS OUTER | | 1 | 322 | 16 (7)| 00:00:01 |
| 24 | VIEW | | 1 | 264 | 15 (7)| 00:00:01 |
| 25 | WINDOW BUFFER | | 1 | 254 | 15 (7)| 00:00:01 |
| 26 | VIEW | | 1 | 254 | 15 (7)| 00:00:01 |
| 27 | WINDOW SORT | | 1 | 532 | 15 (7)| 00:00:01 |
| 28 | NESTED LOOPS OUTER | | 1 | 532 | 13 (0)| 00:00:01 |
| 29 | NESTED LOOPS | | 1 | 503 | 12 (0)| 00:00:01 |
| 30 | NESTED LOOPS OUTER | | 1 | 474 | 11 (0)| 00:00:01 |
| 31 | NESTED LOOPS OUTER | | 1 | 445 | 10 (0)| 00:00:01 |
| 32 | NESTED LOOPS | | 1 | 390 | 9 (0)| 00:00:01 |
| 33 | NESTED LOOPS OUTER | | 1 | 303 | 8 (0)| 00:00:01 |
| 34 | NESTED LOOPS | | 1 | 258 | 7 (0)| 00:00:01 |
| 35 | NESTED LOOPS | | 1 | 240 | 6 (0)| 00:00:01 |
| 36 | NESTED LOOPS | | 1 | 198 | 5 (0)| 00:00:01 |
| 37 | NESTED LOOPS | | 1 | 171 | 4 (0)| 00:00:01 |
| 38 | VIEW | | 1 | 143 | 3 (0)| 00:00:01 |
| 39 | NESTED LOOPS | | 1 | 179 | 3 (0)| 00:00:01 |
| 40 | NESTED LOOPS | | 1 | 92 | 2 (0)| 00:00:01 |
| 41 | ROWID TABLE ACCESS BY INDEX | PS_CS_AUFTRAG_TB | 1 | 41 | 1 (0)| 00:00:01 |
|* 42 | INDEX UNIQUE SCAN | PS_CS_AUFTRAG_TB | 1 | | 1 (0)| 00:00:01 |
| 43 | ROWID TABLE ACCESS BY INDEX | PS_CS_AUFPOS_TB | 1 | 51 | 1 (0)| 00:00:01 |
|* 44 | INDEX UNIQUE SCAN | PS_CS_AUFPOS_TB | 1 | | 1 (0)| 00:00:01 |
| 45 | OWID TABLE ACCESS BY INDEX R | PS_CS_AUFLIEF_TB | 1 | 87 | 1 (0)| 00:00:01 |
|* 46 | INDEX UNIQUE SCAN | PS_CS_AUFLIEF_TB | 1 | | 1 (0)| 00:00:01 |
| 47 | ID TABLE ACCESS BY INDEX ROW | PS_CS_ARTIKEL_TB | 1 | 28 | 1 (0)| 00:00:01 |
|* 48 | INDEX UNIQUE SCAN | PS_CS_ARTIKEL_TB | 1 | | 1 (0)| 00:00:01 |
| 49 | D TABLE ACCESS BY INDEX ROWI | PS_CS_OBJEINW_TB | 1 | 27 | 1 (0)| 00:00:01 |
|* 50 | INDEX UNIQUE SCAN | PS_CS_OBJEINW_TB | 1 | | 1 (0)| 00:00:01 |
| 51 | TABLE ACCESS BY INDEX ROWID | PS_CS_MANDOBJ_TB | 1 | 42 | 1 (0)| 00:00:01 |
|* 52 | INDEX UNIQUE SCAN | PS_CS_MANDOBJ_TB | 1 | | 1 (0)| 00:00:01 |
| 53 | TABLE ACCESS BY INDEX ROWID | PS_CS_OBJSTEUER_TB | 1 | 18 | 1 (0)| 00:00:01 |
|* 54 | INDEX RANGE SCAN | PS_CS_OBJSTEUER_TB | 1 | | 1 (0)| 00:00:01 |
| 55 | SORT AGGREGATE | | 1 | 12 | | |
| 56 | FIRST ROW | | 1 | 12 | 1 (0)| 00:00:01 |
|* 57 | X) INDEX RANGE SCAN (MIN/MA | PS_CS_OBJSTEUER_TB | 1 | 12 | 1 (0)| 00:00:01 |
| 58 | TABLE ACCESS BY INDEX ROWID | PS_CS_AKT_PROD_TB | 1 | 45 | 1 (0)| 00:00:01 |
|* 59 | INDEX UNIQUE SCAN | PS_CS_AKT_PROD_TB | 1 | | 1 (0)| 00:00:01 |
|* 60 | TABLE ACCESS BY INDEX ROWID | PS_CS_HEFTFOLGE_TB | 6 | 522 | 1 (0)| 00:00:01 |
|* 61 | INDEX RANGE SCAN | PS_CS_HEFTFOLGE_TB | 2 | | 1 (0)| 00:00:01 |
| 62 | TABLE ACCESS BY INDEX ROWID | PS_CS_HEFTFOLGE_TB | 1 | 55 | 1 (0)| 00:00:01 |
|* 63 | INDEX UNIQUE SCAN | PS_CS_HEFTFOLGE_TB | 1 | | 1 (0)| 00:00:01 |
| 64 | TABLE ACCESS BY INDEX ROWID | PS_CS_HEFTFOLGE_TB | 1 | 29 | 1 (0)| 00:00:01 |
|* 65 | INDEX RANGE SCAN | PS0CS_HEFTFOLGE_TB | 1 | | 1 (0)| 00:00:01 |
| 66 | TABLE ACCESS BY INDEX ROWID | PS_CS_HEFTFOLGE_TB | 1 | 29 | 1 (0)| 00:00:01 |
|* 67 | INDEX RANGE SCAN | PS0CS_HEFTFOLGE_TB | 1 | | 1 (0)| 00:00:01 |
| 68 | TABLE ACCESS BY INDEX ROWID | PS_CS_HEFTFOLGE_TB | 1 | 29 | 1 (0)| 00:00:01 |
|* 69 | INDEX RANGE SCAN | PS0CS_HEFTFOLGE_TB | 1 | | 1 (0)| 00:00:01 |
|* 70 | TABLE ACCESS BY INDEX ROWID | PS_CS_SRY_REKLA_TB | 1 | 58 | 1 (0)| 00:00:01 |
|* 71 | INDEX RANGE SCAN | PSCCS_SRY_REKLA_TB | 1 | | 1 (0)| 00:00:01 |
|* 72 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFUNT_TB | 1 | 52 | 1 (0)| 00:00:01 |
|* 73 | INDEX RANGE SCAN | PS_CS_AUFUNT_TB | 1 | | 1 (0)| 00:00:01 |
|* 74 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFUNT_TB | 1 | 50 | 1 (0)| 00:00:01 |
|* 75 | INDEX RANGE SCAN | PS_CS_AUFUNT_TB | 1 | | 1 (0)| 00:00:01 |
|* 76 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFUNT_TB | 1 | 64 | 1 (0)| 00:00:01 |
|* 77 | INDEX RANGE SCAN | PS_CS_AUFUNT_TB | 1 | | 1 (0)| 00:00:01 |
|* 78 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFUNT_TB | 1 | 52 | 1 (0)| 00:00:01 |
|* 79 | INDEX RANGE SCAN | PS_CS_AUFUNT_TB | 1 | | 1 (0)| 00:00:01 |
|* 80 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFVERS_TB | 1 | 57 | 1 (0)| 00:00:01 |
|* 81 | INDEX RANGE SCAN | PS_CS_AUFVERS_TB | 2 | | 1 (0)| 00:00:01 |
| 82 | TABLE ACCESS BY INDEX ROWID | PS_CS_WVS_HFOLG_TB | 1 | 65 | 1 (0)| 00:00:01 |
|* 83 | INDEX UNIQUE SCAN | PS_CS_WVS_HFOLG_TB | 1 | | 1 (0)| 00:00:01 |
| 84 | TABLE ACCESS BY INDEX ROWID | PS_CS_VERSTRACK_TB | 1 | 58 | 1 (0)| 00:00:01 |
|* 85 | INDEX RANGE SCAN | PS1CS_VERSTRACK_TB | 1 | | 1 (0)| 00:00:01 |
|* 86 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFPOS_TB | 1 | 43 | 1 (0)| 00:00:01 |
|* 87 | INDEX RANGE SCAN | PSBCS_AUFPOS_TB | 1 | | 1 (0)| 00:00:01 |
| 88 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFLIEF_TB | 1 | 38 | 1 (0)| 00:00:01 |
|* 89 | INDEX RANGE SCAN | PS_CS_AUFLIEF_TB | 1 | | 1 (0)| 00:00:01 |
| 90 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFADR_TB | 1 | 90 | 1 (0)| 00:00:01 |
|* 91 | INDEX UNIQUE SCAN | PS_CS_AUFADR_TB | 1 | | 1 (0)| 00:00:01 |
| 92 | SORT AGGREGATE | | 1 | 49 | | |
|* 93 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFADR_TB | 1 | 49 | 1 (0)| 00:00:01 |
|* 94 | INDEX RANGE SCAN | PS_CS_AUFADR_TB | 1 | | 1 (0)| 00:00:01 |
| 95 | TABLE ACCESS BY INDEX ROWID | PS_CS_ADRART_TB | 1 | 68 | 1 (0)| 00:00:01 |
|* 96 | INDEX RANGE SCAN | PS_CS_ADRART_TB | 1 | | 1 (0)| 00:00:01 |
| 97 | SORT AGGREGATE | | 1 | 70 | | |
|* 98 | TABLE ACCESS BY INDEX ROWID | PS_CS_ADRART_TB | 1 | 70 | 1 (0)| 00:00:01 |
|* 99 | INDEX RANGE SCAN | PS_CS_ADRART_TB | 1 | | 1 (0)| 00:00:01 |
| 100 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFADR_TB | 1 | 90 | 1 (0)| 00:00:01 |
|*101 | INDEX RANGE SCAN | PS_CS_AUFADR_TB | 1 | | 1 (0)| 00:00:01 |
| 102 | TABLE ACCESS BY INDEX ROWID | PS_CS_ADRART_TB | 1 | 68 | 1 (0)| 00:00:01 |
|*103 | INDEX RANGE SCAN | PS_CS_ADRART_TB | 1 | | 1 (0)| 00:00:01 |
| 104 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFLIEFDT_TB | 1 | 50 | 1 (0)| 00:00:01 |
|*105 | INDEX RANGE SCAN | PS_CS_AUFLIEFDT_TB | 1 | | 1 (0)| 00:00:01 |
| 106 | SORT AGGREGATE | | 1 | 36 | | |
| 107 | FIRST ROW | | 1 | 36 | 1 (0)| 00:00:01 |
|*108 | INDEX RANGE SCAN (MIN/MAX) | PS_CS_AUFLIEFDT_TB | 1 | 36 | 1 (0)| 00:00:01 |
| 109 | SORT AGGREGATE | | 1 | 49 | | |
|*110 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFADR_TB | 1 | 49 | 1 (0)| 00:00:01 |
|*111 | INDEX RANGE SCAN | PS_CS_AUFADR_TB | 1 | | 1 (0)| 00:00:01 |
| 112 | SORT AGGREGATE | | 1 | 70 | | |
|*113 | TABLE ACCESS BY INDEX ROWID | PS_CS_ADRART_TB | 1 | 70 | 1 (0)| 00:00:01 |
|*114 | INDEX RANGE SCAN | PS_CS_ADRART_TB | 1 | | 1 (0)| 00:00:01 |
| 115 | SORT AGGREGATE | | 1 | 43 | | |
|*116 | FILTER | | | | | |
|*117 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFPOS_TB | 1 | 43 | 1 (0)| 00:00:01 |
|*118 | INDEX RANGE SCAN | PSBCS_AUFPOS_TB | 1 | | 1 (0)| 00:00:01 |
| 119 | SORT AGGREGATE | | 1 | 39 | | |
|*120 | TABLE ACCESS BY INDEX ROWID | PS_CS_AUFPOS_TB | 1 | 39 | 1 (0)| 00:00:01 |
|*121 | INDEX RANGE SCAN | PSBCS_AUFPOS_TB | 1 | | 1 (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------------------------------
Note
-----
- dynamic statistics used: dynamic sampling (level=4)
- SQL plan baseline SQL_PLAN_3b0ugvyu8w97a4132b007 used for this statement
- statistics feedback used for this statement
In general, you can run this SQL:
select * from v$sql_shared_cursor
where sql_id = '0f83zdknhqsmj';
It will tell you why Oracle is not reusing the existing child cursors.
In your particular case, where you already seem to know that the reason for the non-reuse is that Oracle is re-optimizing the query because of cardinality mismatches, you can go right to this query:
select *
from V$SQL_REOPTIMIZATION_HINTS
where sql_id = '0f83zdknhqsmj';
That should give you insight into which plan step is involved in the cardinality mismatch.
Related
I am working to further optimize the following query. I have already had a lot of success optimizing the query up to this point, but now I am looking for help from others for ideas. I appreciate your help.
The following query takes over 200 seconds to complete yet the two individual WITH clause queries (receiving_1 and receiving_2) that make up the "UNION ALL" take less than 4 seconds each.
receiving_1 -- 58 recs in 3.4 secs; cost 295 (no UNION)
receiving_2 -- 0 recs in 3.8 secs; cost 295 (no UNION)
UNION ALL of 1+2 -- 58 recs in 203.1 secs; cost 300 (UNION ALL)
I was hoping "rownum" would help optimize the "UNION ALL", but it did not. This attempt was based on a note from AskTom --> Files --> SQLTechniques.zip (between 61 and 72)
When you have two queries that run light speed separately
But not so together
Generally a mixed “CBO/RBO” problem
Use of RBO with a feature that kicks in the CBO
Rownum can be a temporary fix till all things are CBO
NOTE: One optimization that avoids this issue is embedded replacement parameters or cursor parameters that greatly reduce the rows at key points in the query. However, because I need to run this query through a database link against a read-only database, the following options are not available for this query.
dbms_sql over database link: query is too long; dbs_sql does not accept a lob over database link; also DBAs don't allow the running of any PL/SQL in the read-only database.
pipelined function: pipelined function has known bug over database link between 19c and 11g so fails
sys_refcursor via PL/SQL: cursors are not supported over database links
set parameter values in PL/SQL package and use them in view: not allowed to execute any code in read-only database (I am still bugging the DBAs to allow this. This might be my best hope if I am not able to optimize the below query to run as a view.)
NOTE: In an attempt at providing a good test case with as little code as possible, the below SQL (4,584 chars, 88 line breaks) is a greatly simplified version of the actual SQL (93,683 chars, 2,014 line breaks) I am developing. The original SQL has already gone through several rounds of optimizations to bring the runtime down from over an hour to under 10 seconds. This latest challenge is that the SQL has to be rewritten as a view as opposed to a SQL file with embedded substitution parameters. The substitution parameters were key to the optimizations up to now. I am now refactoring the SQL to work as a view in Oracle 11gR2 to be called via a database link from Oracle 19c. A view has no parameters, obviously. The driving parameters (ledger, OU, period) will be WHERE clause conditions when querying the view.
Big picture: The actual SQL under development is an amalgamation of 6 report queries that share a lot of duplicated code. My work is to convert all six source report queries into an efficient extract for importing into a new database schema for reconciliation purposes.
with
gccs as (
select
gcc.code_combination_id
from apps.gl_code_combinations gcc
where 1=1
AND regexp_like(gcc.segment1,'^[0-9]{4}$') -- only include 4-digit numbers
AND gcc.segment1 BETWEEN to_char('1500') and to_char('1504')
AND regexp_like(gcc.segment3,'^[0-9]{4}$') -- only include 4-digit numbers
AND ( gcc.segment3 BETWEEN to_char('5000') and to_char('5999')
OR gcc.segment3 in ('6000','6002','6003','6004','6005','6006','6007','6008','6009','6010','6011','6012','6013','6014','6017','6018','6019','6020','6021','6022','6023','6024','6025','6026','6027','6028','6029','6030','6031','6032',
'6033','6034','6035','6036','6037','6038','6039','6040','6041','6042','6043','6044','6045','6046','6047','6048','6049','6050','6051','6052','6053','6054','6055','6056','6058','6060','6061','6062','6063','6064',
'6065','6066','6067','6068','6069','6070','6071','6072','6073','6074','6075','6076','6077','6084','6085','6086','6087','6088','6089','6090','6091','6092','6093','6094','6095','6096','6097','6098','6099','6100',
'6101','6102','6103','6104','6105','6106','6120','6121','6130','6131','6140','6150','6151','6155','6158','6162','6990','6991','6992','6993','6994','6995','6996','6997','6998'))
AND regexp_like(gcc.segment6,'^[0-9]{4}$') -- only include 4-digit numbers
AND gcc.segment6 BETWEEN to_char('3000') and to_char('4999')
) -- select count(*) code_combination_id from gccs;
,
base_query as (
SELECT
gl.LEDGER_ID,
hou.organization_id,
gper.PERIOD_NAME,
XAL.AE_HEADER_ID,
XAL.AE_LINE_NUM,
GJB.STATUS BATCH_STATUS,
GJH.JE_CATEGORY,
XAL.ACCOUNTING_CLASS_CODE,
GJH.JE_SOURCE,
GJH.JE_HEADER_ID,
GJL.JE_LINE_NUM
FROM apps.gl_ledgers gl
join apps.hr_operating_units hou
on hou.set_of_books_id = gl.ledger_id
join APPS.GL_JE_LINES GJL
on exists (select null from gccs where gccs.CODE_COMBINATION_ID = GJL.CODE_COMBINATION_ID)
AND (nvl(gjl.stat_amount,0) <> 0 OR (NVL (gjl.accounted_dr, 0) - NVL (gjl.accounted_cr, 0)) <> 0)
join APPS.GL_PERIODS gper
on GJL.PERIOD_NAME = gper.PERIOD_NAME
join APPS.GL_JE_HEADERS GJH
on GJH.JE_HEADER_ID = GJL.JE_HEADER_ID
AND GJH.PERIOD_NAME = gper.PERIOD_NAME
AND GJH.LEDGER_ID = gl.ledger_id
AND GJH.JE_SOURCE = 'Cost Management'
join APPS.GL_JE_BATCHES GJB
on GJB.JE_BATCH_ID = GJH.JE_BATCH_ID
join APPS.GL_IMPORT_REFERENCES GIR
on GIR.JE_HEADER_ID = GJL.JE_HEADER_ID
AND GIR.JE_LINE_NUM = GJL.JE_LINE_NUM
join APPS.XLA_AE_LINES XAL
on XAL.GL_SL_LINK_TABLE = GIR.GL_SL_LINK_TABLE
AND XAL.GL_SL_LINK_ID = GIR.GL_SL_LINK_ID
AND XAL.LEDGER_ID = gl.LEDGER_ID
),
receiving_1 as (
select distinct
bq.LEDGER_ID,
bq.organization_id,
bq.period_name,
bq.AE_HEADER_ID,
bq.AE_LINE_NUM
FROM base_query bq
WHERE bq.BATCH_STATUS = 'P'
AND UPPER(bq.JE_CATEGORY) = UPPER('Receiving')
),
receiving_2 as (
select distinct
bq.LEDGER_ID,
bq.organization_id,
bq.period_name,
bq.AE_HEADER_ID,
bq.AE_LINE_NUM
FROM base_query bq
WHERE bq.ACCOUNTING_CLASS_CODE = 'INTRA'
AND bq.BATCH_STATUS = 'P'
AND UPPER(bq.JE_CATEGORY) = UPPER('Receiving')
),
receiving_all as (
-- the use of "rownum" below sometimes helps to optimize "union all", but does not help in this query
select rownum, x.* from receiving_1 x -- 58 recs in 3.4 secs cost 295 (no UNION)
union all -- 58 recs in 203.1 secs cost 300 (UNION ALL)
select rownum, x.* from receiving_2 x -- 0 recs in 3.8 secs cost 295 (no UNION)
)
select count(*)
from receiving_all
where ledger_id = 2021
and organization_id = 82
and period_name = 'SEP-2020';
AUTOTRACE for receiving_1 part of query"
COUNT(*)
----------
58
Execution Plan
----------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Pstart| Pstop |
-------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 35 | 295 (1)| | |
| 1 | SORT AGGREGATE | | 1 | 35 | | | |
| 2 | VIEW | | 1 | 35 | 295 (1)| | |
| 3 | COUNT | | | | | | |
| 4 | VIEW | | 1 | 35 | 295 (1)| | |
| 5 | HASH UNIQUE | | 1 | 266 | 295 (1)| | |
| 6 | NESTED LOOPS | | 1 | 266 | 294 (1)| | |
| 7 | NESTED LOOPS | | 1 | 266 | 294 (1)| | |
| 8 | NESTED LOOPS | | 1 | 237 | 236 (1)| | |
| 9 | NESTED LOOPS | | 1 | 214 | 178 (1)| | |
| 10 | NESTED LOOPS | | 1 | 207 | 176 (1)| | |
| 11 | NESTED LOOPS | | 1 | 183 | 176 (1)| | |
| 12 | NESTED LOOPS | | 1 | 152 | 173 (1)| | |
| 13 | NESTED LOOPS | | 1 | 148 | 173 (1)| | |
| 14 | NESTED LOOPS | | 1 | 123 | 172 (1)| | |
| 15 | NESTED LOOPS | | 1 | 101 | 169 (1)| | |
| 16 | NESTED LOOPS | | 1 | 97 | 169 (1)| | |
| 17 | NESTED LOOPS | | 1 | 53 | 167 (1)| | |
| 18 | SORT UNIQUE | | 1 | 21 | 22 (0)| | |
| 19 | TABLE ACCESS BY INDEX ROWID| GL_CODE_COMBINATIONS | 1 | 21 | 22 (0)| | |
| 20 | INDEX RANGE SCAN | GL_CODE_COMBINATIONS_N1 | 117 | | 8 (0)| | |
| 21 | TABLE ACCESS BY INDEX ROWID | GL_JE_LINES | 16 | 512 | 144 (0)| | |
| 22 | INDEX RANGE SCAN | GL_JE_LINES_N1 | 319 | | 4 (0)| | |
| 23 | TABLE ACCESS BY INDEX ROWID | GL_JE_HEADERS | 1 | 44 | 2 (0)| | |
| 24 | INDEX UNIQUE SCAN | GL_JE_HEADERS_U1 | 1 | | 1 (0)| | |
| 25 | INDEX UNIQUE SCAN | GL_LEDGERS_U2 | 1 | 4 | 0 (0)| | |
| 26 | TABLE ACCESS BY INDEX ROWID | HR_ORGANIZATION_INFORMATION | 1 | 22 | 3 (0)| | |
| 27 | INDEX RANGE SCAN | HR_ORGANIZATION_INFORMATIO_FK1 | 30 | | 1 (0)| | |
| 28 | INDEX RANGE SCAN | GL_PERIODS_U1 | 1 | 25 | 1 (0)| | |
| 29 | INDEX UNIQUE SCAN | HR_ORGANIZATION_UNITS_PK | 1 | 4 | 0 (0)| | |
| 30 | TABLE ACCESS BY INDEX ROWID | HR_ORGANIZATION_INFORMATION | 1 | 31 | 3 (0)| | |
| 31 | INDEX RANGE SCAN | HR_ORGANIZATION_INFORMATIO_FK2 | 2 | | 1 (0)| | |
| 32 | INDEX UNIQUE SCAN | HR_ALL_ORGANIZATION_UNTS_TL_PK | 1 | 24 | 0 (0)| | |
| 33 | TABLE ACCESS BY INDEX ROWID | GL_JE_BATCHES | 1 | 7 | 2 (0)| | |
| 34 | INDEX UNIQUE SCAN | GL_JE_BATCHES_U1 | 1 | | 1 (0)| | |
| 35 | TABLE ACCESS BY INDEX ROWID | GL_IMPORT_REFERENCES | 105 | 2415 | 58 (0)| | |
| 36 | INDEX RANGE SCAN | GL_IMPORT_REFERENCES_N1 | 105 | | 3 (0)| | |
| 37 | PARTITION LIST ALL | | 1 | | 57 (0)| 1 | 19 |
| 38 | INDEX RANGE SCAN | XLA_AE_LINES_N4 | 1 | | 57 (0)| 1 | 19 |
| 39 | TABLE ACCESS BY LOCAL INDEX ROWID | XLA_AE_LINES | 1 | 29 | 58 (0)| 1 | 1 |
-------------------------------------------------------------------------------------------------------------------------------------
Note
-----
- 'PLAN_TABLE' is old version
Statistics
----------------------------------------------------------
99 recursive calls
0 db block gets
3500320 consistent gets
0 physical reads
116 redo size
346 bytes sent via SQL*Net to client
4388 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
1 rows processed
AUTOTRACE for receiving_2 part of query:
COUNT(*)
----------
0
Execution Plan
----------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Pstart| Pstop |
-------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 35 | 295 (1)| | |
| 1 | SORT AGGREGATE | | 1 | 35 | | | |
| 2 | VIEW | | 1 | 35 | 295 (1)| | |
| 3 | COUNT | | | | | | |
| 4 | VIEW | | 1 | 35 | 295 (1)| | |
| 5 | HASH UNIQUE | | 1 | 279 | 295 (1)| | |
| 6 | NESTED LOOPS | | 1 | 279 | 294 (1)| | |
| 7 | NESTED LOOPS | | 1 | 279 | 294 (1)| | |
| 8 | NESTED LOOPS | | 1 | 272 | 292 (1)| | |
| 9 | NESTED LOOPS | | 1 | 230 | 234 (1)| | |
| 10 | NESTED LOOPS | | 1 | 207 | 176 (1)| | |
| 11 | NESTED LOOPS | | 1 | 183 | 176 (1)| | |
| 12 | NESTED LOOPS | | 1 | 152 | 173 (1)| | |
| 13 | NESTED LOOPS | | 1 | 148 | 173 (1)| | |
| 14 | NESTED LOOPS | | 1 | 126 | 170 (1)| | |
| 15 | NESTED LOOPS | | 1 | 122 | 170 (1)| | |
| 16 | NESTED LOOPS | | 1 | 97 | 169 (1)| | |
| 17 | NESTED LOOPS | | 1 | 53 | 167 (1)| | |
| 18 | SORT UNIQUE | | 1 | 21 | 22 (0)| | |
| 19 | TABLE ACCESS BY INDEX ROWID| GL_CODE_COMBINATIONS | 1 | 21 | 22 (0)| | |
| 20 | INDEX RANGE SCAN | GL_CODE_COMBINATIONS_N1 | 117 | | 8 (0)| | |
| 21 | TABLE ACCESS BY INDEX ROWID | GL_JE_LINES | 16 | 512 | 144 (0)| | |
| 22 | INDEX RANGE SCAN | GL_JE_LINES_N1 | 319 | | 4 (0)| | |
| 23 | TABLE ACCESS BY INDEX ROWID | GL_JE_HEADERS | 1 | 44 | 2 (0)| | |
| 24 | INDEX UNIQUE SCAN | GL_JE_HEADERS_U1 | 1 | | 1 (0)| | |
| 25 | INDEX RANGE SCAN | GL_PERIODS_U1 | 1 | 25 | 1 (0)| | |
| 26 | INDEX UNIQUE SCAN | GL_LEDGERS_U2 | 1 | 4 | 0 (0)| | |
| 27 | TABLE ACCESS BY INDEX ROWID | HR_ORGANIZATION_INFORMATION | 1 | 22 | 3 (0)| | |
| 28 | INDEX RANGE SCAN | HR_ORGANIZATION_INFORMATIO_FK1 | 30 | | 1 (0)| | |
| 29 | INDEX UNIQUE SCAN | HR_ORGANIZATION_UNITS_PK | 1 | 4 | 0 (0)| | |
| 30 | TABLE ACCESS BY INDEX ROWID | HR_ORGANIZATION_INFORMATION | 1 | 31 | 3 (0)| | |
| 31 | INDEX RANGE SCAN | HR_ORGANIZATION_INFORMATIO_FK2 | 2 | | 1 (0)| | |
| 32 | INDEX UNIQUE SCAN | HR_ALL_ORGANIZATION_UNTS_TL_PK | 1 | 24 | 0 (0)| | |
| 33 | TABLE ACCESS BY INDEX ROWID | GL_IMPORT_REFERENCES | 105 | 2415 | 58 (0)| | |
| 34 | INDEX RANGE SCAN | GL_IMPORT_REFERENCES_N1 | 105 | | 3 (0)| | |
| 35 | PARTITION LIST ALL | | 1 | 42 | 58 (0)| 1 | 19 |
| 36 | TABLE ACCESS BY LOCAL INDEX ROWID | XLA_AE_LINES | 1 | 42 | 58 (0)| 1 | 19 |
| 37 | INDEX RANGE SCAN | XLA_AE_LINES_N4 | 1 | | 57 (0)| 1 | 19 |
| 38 | INDEX UNIQUE SCAN | GL_JE_BATCHES_U1 | 1 | | 1 (0)| | |
| 39 | TABLE ACCESS BY INDEX ROWID | GL_JE_BATCHES | 1 | 7 | 2 (0)| | |
-------------------------------------------------------------------------------------------------------------------------------------
Note
-----
- 'PLAN_TABLE' is old version
Statistics
----------------------------------------------------------
99 recursive calls
0 db block gets
3451912 consistent gets
0 physical reads
0 redo size
345 bytes sent via SQL*Net to client
4385 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
1 rows processed
AUTOTRACE for UNION ALL of full query that includes both request_1 and request_2
COUNT(*)
----------
58
Execution Plan
----------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Pstart| Pstop |
----------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 35 | 300 (1)| | |
| 1 | TEMP TABLE TRANSFORMATION | | | | | | |
| 2 | LOAD AS SELECT | SYS_TEMP_0FD9D6767_FC3F7B00 | | | | | |
| 3 | NESTED LOOPS | | 1 | 279 | 294 (1)| | |
| 4 | NESTED LOOPS | | 1 | 279 | 294 (1)| | |
| 5 | NESTED LOOPS | | 1 | 237 | 236 (1)| | |
| 6 | NESTED LOOPS | | 1 | 214 | 178 (1)| | |
| 7 | NESTED LOOPS | | 1 | 207 | 176 (1)| | |
| 8 | NESTED LOOPS | | 1 | 183 | 176 (1)| | |
| 9 | NESTED LOOPS | | 1 | 152 | 173 (1)| | |
| 10 | NESTED LOOPS | | 1 | 148 | 173 (1)| | |
| 11 | NESTED LOOPS | | 1 | 126 | 170 (1)| | |
| 12 | NESTED LOOPS | | 1 | 122 | 170 (1)| | |
| 13 | NESTED LOOPS | | 1 | 78 | 168 (1)| | |
| 14 | NESTED LOOPS | | 1 | 53 | 167 (1)| | |
| 15 | SORT UNIQUE | | 1 | 21 | 22 (0)| | |
| 16 | TABLE ACCESS BY INDEX ROWID| GL_CODE_COMBINATIONS | 1 | 21 | 22 (0)| | |
| 17 | INDEX RANGE SCAN | GL_CODE_COMBINATIONS_N1 | 117 | | 8 (0)| | |
| 18 | TABLE ACCESS BY INDEX ROWID | GL_JE_LINES | 16 | 512 | 144 (0)| | |
| 19 | INDEX RANGE SCAN | GL_JE_LINES_N1 | 319 | | 4 (0)| | |
| 20 | INDEX RANGE SCAN | GL_PERIODS_U1 | 1 | 25 | 1 (0)| | |
| 21 | TABLE ACCESS BY INDEX ROWID | GL_JE_HEADERS | 1 | 44 | 2 (0)| | |
| 22 | INDEX UNIQUE SCAN | GL_JE_HEADERS_U1 | 1 | | 1 (0)| | |
| 23 | INDEX UNIQUE SCAN | GL_LEDGERS_U2 | 1 | 4 | 0 (0)| | |
| 24 | TABLE ACCESS BY INDEX ROWID | HR_ORGANIZATION_INFORMATION | 1 | 22 | 3 (0)| | |
| 25 | INDEX RANGE SCAN | HR_ORGANIZATION_INFORMATIO_FK1 | 30 | | 1 (0)| | |
| 26 | INDEX UNIQUE SCAN | HR_ORGANIZATION_UNITS_PK | 1 | 4 | 0 (0)| | |
| 27 | TABLE ACCESS BY INDEX ROWID | HR_ORGANIZATION_INFORMATION | 1 | 31 | 3 (0)| | |
| 28 | INDEX RANGE SCAN | HR_ORGANIZATION_INFORMATIO_FK2 | 2 | | 1 (0)| | |
| 29 | INDEX UNIQUE SCAN | HR_ALL_ORGANIZATION_UNTS_TL_PK | 1 | 24 | 0 (0)| | |
| 30 | TABLE ACCESS BY INDEX ROWID | GL_JE_BATCHES | 1 | 7 | 2 (0)| | |
| 31 | INDEX UNIQUE SCAN | GL_JE_BATCHES_U1 | 1 | | 1 (0)| | |
| 32 | TABLE ACCESS BY INDEX ROWID | GL_IMPORT_REFERENCES | 105 | 2415 | 58 (0)| | |
| 33 | INDEX RANGE SCAN | GL_IMPORT_REFERENCES_N1 | 105 | | 3 (0)| | |
| 34 | PARTITION LIST ALL | | 1 | | 57 (0)| 1 | 19 |
| 35 | INDEX RANGE SCAN | XLA_AE_LINES_N4 | 1 | | 57 (0)| 1 | 19 |
| 36 | TABLE ACCESS BY LOCAL INDEX ROWID | XLA_AE_LINES | 1 | 42 | 58 (0)| 1 | 1 |
| 37 | SORT AGGREGATE | | 1 | 35 | | | |
| 38 | VIEW | | 2 | 70 | 6 (34)| | |
| 39 | UNION-ALL | | | | | | |
| 40 | COUNT | | | | | | |
| 41 | VIEW | | 1 | 35 | 3 (34)| | |
| 42 | HASH UNIQUE | | 1 | 44 | 3 (34)| | |
| 43 | VIEW | | 1 | 44 | 2 (0)| | |
| 44 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6767_FC3F7B00 | 1 | 74 | 2 (0)| | |
| 45 | COUNT | | | | | | |
| 46 | VIEW | | 1 | 35 | 3 (34)| | |
| 47 | HASH UNIQUE | | 1 | 61 | 3 (34)| | |
| 48 | VIEW | | 1 | 61 | 2 (0)| | |
| 49 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6767_FC3F7B00 | 1 | 74 | 2 (0)| | |
----------------------------------------------------------------------------------------------------------------------------------
Note
-----
- 'PLAN_TABLE' is old version
Statistics
----------------------------------------------------------
766 recursive calls
83076 db block gets
270487689 consistent gets
81660 physical reads
676 redo size
346 bytes sent via SQL*Net to client
4582 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
1 rows processed
As I don't know the underlying tables, their structure and their data, I can only guess. Having said that, I'd try the following things (not knowing if any of the steps are helpful or not!):
remove the rownum from receiving_all
add the where clause from the main query to each of the subqueries in receiving_all. The optimizer might be able to infer this, but I am not sure.
change union all to union in receiving_all and remove the distinct from receiving_1 and receiving_2
receiving_2 seems to be included in receiving_2?
If 4. is not the case, I would combine both into a single query with WHERE UPPER(bq.JE_CATEGORY) = UPPER('Receiving') AND ( (<conditions for 1>) OR (<conditions for 2>) )
I would try if UPPER(bq.JE_CATEGORY) can be avoided. Functions prevent index access.
In case you can create tables, I'd unroll the values of gccs into two tables, one for segment_1, and another table for segment_2.
If 7. is not an option, I'd add the hint select /*+ materialize */ gcc.code_combination_id to gcc.
I'm very curious to see which suggestion has any positive impact...
I need to get data from an oracle DB to paint some sort of matrix in an html table. The query I needed turned out to be very complex and slow, so I decided to implement pagination.
I followed many articles and posts, but the one I liked the most was this one: On rownum and limiting results
But it doesn't seem to work, the execution takes as long time as if there was no rows restriction, sometimes it even takes longer.
Please keep in mind than I'm new with oracle, I'm used to recent versions of MS SQL
Here's a brief example of what my query looks like:
SELECT * FROM (
SELECT /*+ FIRST_ROWS(n) */ a.*, ROWNUM rnum FROM (
WITH T1 AS (
SELECT ... FROM VIEW_1
INNER JOIN ...
WHERE ...
GROUP BY ...
),
T2 AS (
SELECT ... FROM VIEW_2
INNER JOIN ...
WHERE ...
GROUP BY ...
),
T3 AS (
SELECT ... FROM VIEW_3
LEFT JOIN ...
WHERE ...
GROUP BY ...
)
SELECT
T1.LVL,
T1.CRSE,
T2.ID,
T3.GRADE
FROM T1
INNER JOIN T2 ON ...
LEFT JOIN T3 ON ...
ORDER BY T2.ID DESC, T1.LVL, T1.CRSE) a
WHERE ROWNUM <= (PAGE * 50))
WHERE rnum >= ((PAGE-1) * 50);
My actual query is quite larger, and I mostly use views I don't have access to.
I don't know if the /*+ FIRST_ROWS(n) */ works like that... and also don't think I can set a variable there...
I was expecting the execution time to be much lower that without the ROWNUM check, but it just doesn't work, and I've read its because of the GROUP BY usage. Can someone please help me make my pagination faster?
EDIT:
Here's the EXPLAIN PLAN from my query, I hope it helps:
Plan hash value: 3394899150
-----------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 3950 | 648K| | 17918 (1)| 00:03:36 |
|* 1 | VIEW | | 3950 | 648K| | 17918 (1)| 00:03:36 |
|* 2 | COUNT STOPKEY | | | | | | |
| 3 | VIEW | | 8424 | 1275K| | 17918 (1)| 00:03:36 |
| 4 | TEMP TABLE TRANSFORMATION | | | | | | |
| 5 | LOAD AS SELECT | SYS_TEMP_0FD9D6FD2_17D15EA9 | | | | | |
| 6 | HASH UNIQUE | | 36 | 2052 | | 250 (1)| 00:00:03 |
| 7 | VIEW | PS_UAG_ISBI_MAT_VW | 36 | 2052 | | 249 (1)| 00:00:03 |
|* 8 | HASH JOIN | | 36 | 3744 | | 249 (1)| 00:00:03 |
| 9 | NESTED LOOPS | | 34 | 2312 | | 14 (0)| 00:00:01 |
| 10 | NESTED LOOPS | | 44 | 2312 | | 14 (0)| 00:00:01 |
| 11 | NESTED LOOPS | | 1 | 46 | | 5 (0)| 00:00:01 |
| 12 | TABLE ACCESS BY INDEX ROWID | PS_ACAD_PROG_TBL | 1 | 29 | | 4 (0)| 00:00:01 |
|* 13 | INDEX SKIP SCAN | PS1ACAD_PROG_TBL | 1 | | | 3 (0)| 00:00:01 |
|* 14 | INDEX RANGE SCAN | PS1ACAD_ORG_TBL | 1 | 17 | | 1 (0)| 00:00:01 |
|* 15 | INDEX RANGE SCAN | PS2CRSE_OFFER | 44 | | | 1 (0)| 00:00:01 |
|* 16 | TABLE ACCESS BY INDEX ROWID | PS_CRSE_OFFER | 33 | 726 | | 9 (0)| 00:00:01 |
| 17 | VIEW | | 12227 | 429K| | 235 (1)| 00:00:03 |
|* 18 | HASH JOIN RIGHT OUTER | | 12227 | 573K| | 235 (1)| 00:00:03 |
|* 19 | INDEX FAST FULL SCAN | PS_CRSE_ATTRIBUTES | 7690 | 135K| | 98 (0)| 00:00:02 |
| 20 | TABLE ACCESS FULL | PS_CRSE_CATALOG | 12227 | 358K| | 136 (0)| 00:00:02 |
| 21 | LOAD AS SELECT | SYS_TEMP_0FD9D6FD3_17D15EA9 | | | | | |
| 22 | VIEW | | 682 | 36146 | | 1091 (1)| 00:00:14 |
|* 23 | HASH JOIN | | 682 | 41602 | | 1091 (1)| 00:00:14 |
|* 24 | TABLE ACCESS FULL | TYM_TRAYECTORIA | 682 | 17050 | | 513 (1)| 00:00:07 |
| 25 | INDEX FAST FULL SCAN | PS0PERSONAL_DATA | 255K| 8985K| | 577 (1)| 00:00:07 |
| 26 | LOAD AS SELECT | SYS_TEMP_0FD9D6FD4_17D15EA9 | | | | | |
| 27 | HASH GROUP BY | | 107 | 1605 | | 16164 (1)| 00:03:14 |
| 28 | VIEW | | 107 | 1605 | | 16163 (1)| 00:03:14 |
|* 29 | HASH JOIN | | 107 | 2461 | | 16163 (1)| 00:03:14 |
| 30 | VIEW | | 682 | 5456 | | 3 (0)| 00:00:01 |
| 31 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6FD3_17D15EA9 | 682 | 36146 | | 3 (0)| 00:00:01 |
| 32 | VIEW | PS_UAG_ISBI_CAL_VW | 6411 | 96165 | | 16160 (1)| 00:03:14 |
| 33 | SORT UNIQUE | | 6411 | 7004K| 1960K| 16160 (1)| 00:03:14 |
| 34 | UNION-ALL | | | | | | |
|* 35 | HASH JOIN | | 6342 | 1839K| | 15289 (1)| 00:03:04 |
|* 36 | INDEX FAST FULL SCAN | PS_CRSE_ATTRIBUTES | 7690 | 135K| | 98 (0)| 00:00:02 |
|* 37 | HASH JOIN | | 4943 | 1346K| | 15191 (1)| 00:03:03 |
|* 38 | HASH JOIN | | 4943 | 1168K| | 10790 (1)| 00:02:10 |
| 39 | INDEX FAST FULL SCAN | PS1TERM_TBL | 1256 | 31400 | | 4 (0)| 00:00:01 |
|* 40 | HASH JOIN | | 4943 | 1047K| | 10786 (1)| 00:02:10 |
| 41 | INDEX FAST FULL SCAN | PS0CRSE_CATALOG | 12227 | 358K| | 31 (0)| 00:00:01 |
|* 42 | HASH JOIN | | 4985 | 910K| | 10755 (1)| 00:02:10 |
| 43 | TABLE ACCESS FULL | PS_ACAD_ORG_TBL | 549 | 23058 | | 7 (0)| 00:00:01 |
|* 44 | HASH JOIN | | 5297 | 750K| 2856K| 10748 (1)| 00:02:09 |
| 45 | TABLE ACCESS FULL | PS_CLASS_TBL | 52112 | 2239K| | 650 (1)| 00:00:08 |
|* 46 | HASH JOIN | | 100K| 9893K| | 9422 (1)| 00:01:54 |
| 47 | TABLE ACCESS FULL | PS_ACAD_PROG_TBL | 313 | 18467 | | 5 (0)| 00:00:01 |
|* 48 | TABLE ACCESS FULL | PS_STDNT_ENRL | 986K| 39M| | 9414 (1)| 00:01:53 |
| 49 | TABLE ACCESS FULL | PS_PERSONAL_DATA | 255K| 9235K| | 4400 (1)| 00:00:53 |
| 50 | NESTED LOOPS | | 69 | 19596 | | 462 (1)| 00:00:06 |
| 51 | NESTED LOOPS | | 69 | 19596 | | 462 (1)| 00:00:06 |
|* 52 | HASH JOIN | | 69 | 17043 | | 324 (1)| 00:00:04 |
|* 53 | HASH JOIN | | 69 | 15318 | | 320 (1)| 00:00:04 |
|* 54 | HASH JOIN | | 105 | 21420 | | 222 (1)| 00:00:03 |
|* 55 | HASH JOIN | | 101 | 17574 | | 191 (1)| 00:00:03 |
|* 56 | HASH JOIN | | 101 | 14443 | | 88 (0)| 00:00:02 |
|* 57 | HASH JOIN | | 314 | 31714 | | 12 (0)| 00:00:01 |
| 58 | TABLE ACCESS FULL | PS_ACAD_PROG_TBL | 313 | 18467 | | 5 (0)| 00:00:01 |
| 59 | TABLE ACCESS FULL | PS_ACAD_ORG_TBL | 549 | 23058 | | 7 (0)| 00:00:01 |
| 60 | VIEW | | 7540 | 309K| | 76 (0)| 00:00:01 |
|* 61 | HASH JOIN | | 7540 | 493K| | 76 (0)| 00:00:01 |
| 62 | TABLE ACCESS FULL | PS_TRNS_CRSE_SCH | 597 | 16119 | | 6 (0)| 00:00:01 |
| 63 | TABLE ACCESS FULL | PS_TRNS_CRSE_DTL | 7540 | 294K| | 70 (0)| 00:00:01 |
| 64 | TABLE ACCESS FULL | PS_CRSE_OFFER | 12227 | 370K| | 102 (0)| 00:00:02 |
| 65 | INDEX FAST FULL SCAN | PS0CRSE_CATALOG | 12227 | 358K| | 31 (0)| 00:00:01 |
|* 66 | INDEX FAST FULL SCAN | PS_CRSE_ATTRIBUTES | 7690 | 135K| | 98 (0)| 00:00:02 |
| 67 | INDEX FAST FULL SCAN | PS1TERM_TBL | 1256 | 31400 | | 4 (0)| 00:00:01 |
|* 68 | INDEX UNIQUE SCAN | PS_PERSONAL_DATA | 1 | | | 1 (0)| 00:00:01 |
| 69 | TABLE ACCESS BY INDEX ROWID | PS_PERSONAL_DATA | 1 | 37 | | 2 (0)| 00:00:01 |
|* 70 | SORT ORDER BY STOPKEY | | 8424 | 1628K| 1736K| 413 (1)| 00:00:05 |
|* 71 | HASH JOIN RIGHT OUTER | | 8424 | 1628K| | 46 (5)| 00:00:01 |
| 72 | VIEW | | 108 | 2700 | | 2 (0)| 00:00:01 |
| 73 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6FD4_17D15EA9 | 108 | 1620 | | 2 (0)| 00:00:01 |
|* 74 | HASH JOIN RIGHT OUTER | | 78 | 13494 | | 44 (5)| 00:00:01 |
| 75 | VIEW | | 26 | 390 | | 24 (5)| 00:00:01 |
| 76 | HASH GROUP BY | | 26 | 702 | | 24 (5)| 00:00:01 |
| 77 | VIEW | | 47 | 1269 | | 24 (5)| 00:00:01 |
| 78 | HASH GROUP BY | | 47 | 2256 | | 24 (5)| 00:00:01 |
|* 79 | HASH JOIN OUTER | | 47 | 2256 | | 23 (0)| 00:00:01 |
|* 80 | HASH JOIN OUTER | | 47 | 1081 | | 21 (0)| 00:00:01 |
| 81 | VIEW | | 36 | 360 | | 2 (0)| 00:00:01 |
| 82 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6FD2_17D15EA9 | 36 | 2052 | | 2 (0)| 00:00:01 |
| 83 | TABLE ACCESS FULL | PS_RQ_GRP_DETL_TBL | 2702 | 35126 | | 19 (0)| 00:00:01 |
| 84 | VIEW | | 108 | 2700 | | 2 (0)| 00:00:01 |
| 85 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6FD4_17D15EA9 | 108 | 1620 | | 2 (0)| 00:00:01 |
|* 86 | HASH JOIN RIGHT OUTER | | 78 | 12324 | | 20 (5)| 00:00:01 |
| 87 | TABLE ACCESS FULL | PS_UAG_PRECARG_SUBJECT | 12 | 168 | | 3 (0)| 00:00:01 |
|* 88 | HASH JOIN RIGHT OUTER | | 78 | 11232 | | 17 (6)| 00:00:01 |
| 89 | VIEW | | 1 | 20 | | 12 (9)| 00:00:01 |
| 90 | HASH GROUP BY | | 1 | 30 | | 12 (9)| 00:00:01 |
| 91 | VIEW | PS_UAG_OFERCRSE_VW | 1 | 30 | | 12 (9)| 00:00:01 |
| 92 | HASH UNIQUE | | 1 | 213 | | 12 (9)| 00:00:01 |
| 93 | NESTED LOOPS OUTER | | 1 | 213 | | 11 (0)| 00:00:01 |
| 94 | NESTED LOOPS OUTER | | 1 | 177 | | 9 (0)| 00:00:01 |
| 95 | NESTED LOOPS OUTER | | 1 | 139 | | 6 (0)| 00:00:01 |
|* 96 | TABLE ACCESS BY INDEX ROWID| PS_CLASS_TBL | 1 | 69 | | 4 (0)| 00:00:01 |
|* 97 | INDEX RANGE SCAN | PSDCLASS_TBL | 1 | | | 3 (0)| 00:00:01 |
| 98 | TABLE ACCESS BY INDEX ROWID| PS_CLASS_MTG_PAT | 1 | 70 | | 2 (0)| 00:00:01 |
|* 99 | INDEX RANGE SCAN | PS_CLASS_MTG_PAT | 1 | | | 1 (0)| 00:00:01 |
| 100 | TABLE ACCESS BY INDEX ROWID | PS_CLASS_INSTR | 1 | 38 | | 3 (0)| 00:00:01 |
|*101 | INDEX RANGE SCAN | PS_CLASS_INSTR | 1 | | | 2 (0)| 00:00:01 |
| 102 | TABLE ACCESS BY INDEX ROWID | PS_PERSONAL_DATA | 1 | 36 | | 2 (0)| 00:00:01 |
|*103 | INDEX UNIQUE SCAN | PS_PERSONAL_DATA | 1 | | | 1 (0)| 00:00:01 |
| 104 | VIEW | | 78 | 9672 | | 5 (0)| 00:00:01 |
|*105 | HASH JOIN | | 78 | 10140 | | 5 (0)| 00:00:01 |
| 106 | VIEW | | 36 | 2988 | | 2 (0)| 00:00:01 |
| 107 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6FD2_17D15EA9 | 36 | 2052 | | 2 (0)| 00:00:01 |
| 108 | VIEW | | 682 | 32054 | | 3 (0)| 00:00:01 |
| 109 | TABLE ACCESS FULL | SYS_TEMP_0FD9D6FD3_17D15EA9 | 682 | 36146 | | 3 (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter("RNUM">=0)
2 - filter(ROWNUM<=3950)
8 - access("D"."CRSE_ID"="C"."CRSE_ID")
13 - access("A"."ACAD_PROG"='LMC09')
filter("A"."ACAD_PROG"='LMC09')
14 - access("B"."INSTITUTION"="A"."INSTITUTION" AND "B"."ACAD_ORG"="A"."ACAD_ORG")
15 - access("C"."SUBJECT"="A"."ACAD_PLAN")
16 - filter("C"."INSTITUTION"="A"."INSTITUTION")
18 - access("E"."CRSE_ID"(+)="D"."CRSE_ID")
19 - filter("E"."CRSE_ATTR"(+)='0003')
23 - access("PERS"."EMPLID"="TRA"."EMPLID")
24 - filter("TRA"."STRM"='1835' AND "TRA"."ACAD_PLAN"='LMC09')
29 - access("A2"."EMPLID"="CAL"."EMPLID")
35 - access("F"."CRSE_ID"="E"."CRSE_ID")
36 - filter("F"."CRSE_ATTR"='0003')
37 - access("B"."EMPLID"="A"."EMPLID")
38 - access("H"."INSTITUTION"="A"."INSTITUTION" AND "H"."ACAD_CAREER"="A"."ACAD_CAREER" AND "H"."STRM"="A"."STRM")
40 - access("E"."CRSE_ID"="C"."CRSE_ID")
42 - access("G"."INSTITUTION"="A"."INSTITUTION" AND "G"."ACAD_ORG"="D"."ACAD_ORG")
44 - access("C"."INSTITUTION"="A"."INSTITUTION" AND "C"."ACAD_CAREER"="A"."ACAD_CAREER" AND "C"."STRM"="A"."STRM" AND
"C"."CLASS_NBR"="A"."CLASS_NBR" AND "C"."SESSION_CODE"="A"."SESSION_CODE")
46 - access("D"."INSTITUTION"="A"."INSTITUTION" AND "D"."ACAD_CAREER"="A"."ACAD_CAREER" AND
"D"."ACAD_PROG"="A"."ACAD_PROG")
48 - filter("A"."STDNT_ENRL_STATUS"='E')
52 - access("H"."INSTITUTION"="A"."INSTITUTION" AND "H"."ACAD_CAREER"="A"."ACAD_CAREER" AND
"H"."STRM"="A"."ARTICULATION_TERM")
53 - access("F"."CRSE_ID"="E"."CRSE_ID")
54 - access("E"."CRSE_ID"="C"."CRSE_ID")
55 - access("C"."INSTITUTION"="A"."INSTITUTION" AND "C"."ACAD_CAREER"="A"."ACAD_CAREER" AND "C"."CRSE_ID"="A"."CRSE_ID")
56 - access("D"."INSTITUTION"="A"."INSTITUTION" AND "D"."ACAD_CAREER"="A"."ACAD_CAREER" AND
"D"."ACAD_PROG"="A"."ACAD_PROG" AND "G"."INSTITUTION"="A"."INSTITUTION")
57 - access("G"."ACAD_ORG"="D"."ACAD_ORG")
61 - access("B"."EMPLID"="A"."EMPLID" AND "B"."ACAD_CAREER"="A"."ACAD_CAREER" AND "B"."INSTITUTION"="A"."INSTITUTION"
AND "B"."MODEL_NBR"="A"."MODEL_NBR")
66 - filter("F"."CRSE_ATTR"='0003')
68 - access("B"."EMPLID"="A"."EMPLID")
70 - filter(ROWNUM<=3950)
71 - access("C3"."CRSE_ID"(+)="from$_subquery$_019"."CRSE_ID" AND "C3"."EMPLID"(+)="from$_subquery$_019"."EMPLID")
74 - access("R3"."EMPLID"(+)="from$_subquery$_019"."EMPLID" AND
"R3"."RQRMNT_GROUP"(+)="from$_subquery$_019"."RQRMNT_GROUP")
filter("from$_subquery$_019"."RQRMNT_GROUP"<>CASE WHEN ("R3"."RQRMNT_GROUP"(+) IS NOT NULL) THEN ' ' ELSE ' ' END )
79 - access("REQ"."CRSE_ID"="C2"."CRSE_ID"(+))
80 - access("REQ"."RQRMNT_GROUP"(+)="M2"."RQRMNT_GROUP")
filter("M2"."RQRMNT_GROUP"<>CASE WHEN ("REQ"."RQRMNT_GROUP"(+) IS NOT NULL) THEN ' ' ELSE ' ' END )
86 - access("DTL"."CRSE_ID"(+)="M3"."CRSE_ID" AND "A3"."IDTRAYECTORIA"=TO_NUMBER("DTL"."ID_TRAYECTORIA"(+)))
88 - access("H3"."CRSE_ID"(+)="from$_subquery$_019"."CRSE_ID")
96 - filter("A"."SESSION_CODE"='ORD' AND "A"."CLASS_STAT"='A')
97 - access("A"."SUBJECT"='LMC09' AND "A"."STRM"='1853')
99 - access("B"."CRSE_ID"(+)="A"."CRSE_ID" AND "B"."CRSE_OFFER_NBR"(+)="A"."CRSE_OFFER_NBR" AND "B"."STRM"(+)='1853' AND
"B"."SESSION_CODE"(+)='ORD' AND "B"."CLASS_SECTION"(+)="A"."CLASS_SECTION")
101 - access("C"."CRSE_ID"(+)="B"."CRSE_ID" AND "C"."CRSE_OFFER_NBR"(+)="B"."CRSE_OFFER_NBR" AND "C"."STRM"(+)="B"."STRM"
AND "C"."SESSION_CODE"(+)="B"."SESSION_CODE" AND "C"."CLASS_SECTION"(+)="B"."CLASS_SECTION" AND
"C"."CLASS_MTG_NBR"(+)="B"."CLASS_MTG_NBR")
103 - access("D"."EMPLID"(+)="C"."EMPLID")
105 - access("M3"."ACAD_PLAN"="A3"."ACAD_PLAN")
EDIT 2, SOLUTION:
I Managed to find the indexes already configured for the table 'PS_STDNT_ENRL' using the following query:
SELECT
index_owner, index_name, table_name, column_name, column_position
FROM DBA_IND_COLUMNS
WHERE table_name = 'PS_STDNT_ENRL'
ORDER BY
index_owner,
table_name,
index_name,
column_position;
And found the columns needed on my WHERE clause so that the index works.
I modified my query and now its very fast.
ROWNUM only limits the number of rows presented AFTER the query runs and returns ALL rows. So it is still doing all of the work.
If t1.id is numeric, you can use MOD() to reduce the amount of work up front and easily chunk-up your results into as many sections as you desire. By way of example, MOD() of 5 against t1.id would allow you to break the results up into 5 sections corresponding to MOD() results of 0,1,2,3,4.
SELECT MOD(/*t1.id*/1000,5) FROM dual;
In this manner you reduce the number of rows considered in your driving table (t1) so there is less data to be managed after the other tables are joined in.
It would look something like this:
AND MOD(t1.id,5) =
00 -- Partition 1
-- 01 -- Partition 2
-- 02 -- Partition 3
-- 03 -- Partition 4
-- 04 -- Partition 5
I need help forcing Oracle to always use table access by index row id on table "r_rapport" (~60k rows) to subsequently avoid full table scans on "r_attributfeld" (~8m rows) . I have a query resulting in the following plan:
---------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time |
---------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 101 | 22220 | | 63518 (2)| 00:12:43 |
|* 1 | COUNT STOPKEY | | | | | | |
| 2 | VIEW | | 2870 | 616K| | 63518 (2)| 00:12:43 |
|* 3 | SORT ORDER BY STOPKEY | | 2870 | 313K| 696K| 63518 (2)| 00:12:43 |
|* 4 | FILTER | | | | | | |
|* 5 | HASH JOIN SEMI | | 2871 | 314K| | 51920 (2)| 00:10:24 |
|* 6 | HASH JOIN RIGHT SEMI | | 2871 | 299K| | 26084 (2)| 00:05:14 |
| 7 | VIEW | VW_NSO_1 | 214 | 1070 | | 5 (20)| 00:00:01 |
|* 8 | HASH JOIN | | 214 | 5350 | | 5 (20)| 00:00:01 |
|* 9 | INDEX RANGE SCAN | TEST7 | 141 | 1269 | | 2 (0)| 00:00:01 |
|* 10 | INDEX RANGE SCAN | TEST8 | 228 | 3648 | | 2 (0)| 00:00:01 |
|* 11 | HASH JOIN SEMI | | 5848 | 582K| | 26079 (2)| 00:05:13 |
|* 12 | HASH JOIN | | 6547 | 620K| | 243 (2)| 00:00:03 |
|* 13 | INDEX RANGE SCAN | TEST5 | 47 | 470 | | 2 (0)| 00:00:01 |
| 14 | TABLE ACCESS FULL | R_RAPPORT | 60730 | 5159K| | 240 (1)| 00:00:03 |
| 15 | VIEW | VW_SQ_3 | 334K| 1633K| | 25834 (2)| 00:05:11 |
|* 16 | HASH JOIN | | 334K| 14M| 10M| 25834 (2)| 00:05:11 |
| 17 | INDEX FAST FULL SCAN | TEST4 | 476K| 4656K| | 368 (2)| 00:00:05 |
|* 18 | HASH JOIN | | 343K| 11M| 11M| 24214 (2)| 00:04:51 |
|* 19 | TABLE ACCESS FULL | R_ATTRIBUTFELD | 343K| 7722K| | 20483 (2)| 00:04:06 |
| 20 | INDEX FAST FULL SCAN| TEST3 | 1670K| 17M| | 1324 (1)| 00:00:16 |
| 21 | VIEW | VW_SQ_2 | 334K| 1633K| | 25834 (2)| 00:05:11 |
|* 22 | HASH JOIN | | 334K| 14M| 10M| 25834 (2)| 00:05:11 |
| 23 | INDEX FAST FULL SCAN | TEST4 | 476K| 4656K| | 368 (2)| 00:00:05 |
|* 24 | HASH JOIN | | 343K| 11M| 11M| 24214 (2)| 00:04:51 |
|* 25 | TABLE ACCESS FULL | R_ATTRIBUTFELD | 343K| 7722K| | 20483 (2)| 00:04:06 |
| 26 | INDEX FAST FULL SCAN | TEST3 | 1670K| 17M| | 1324 (1)| 00:00:16 |
|* 27 | INDEX RANGE SCAN | TEST6 | 1 | 8 | | 8 (0)| 00:00:01 |
---------------------------------------------------------------------------------------------------------
By adding a FIRST_ROWS(1) hint, this changes to the much more desired plan:
----------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 220 | 96 (0)| 00:00:02 |
|* 1 | COUNT STOPKEY | | | | | |
| 2 | VIEW | | 1 | 220 | 96 (0)| 00:00:02 |
|* 3 | FILTER | | | | | |
| 4 | NESTED LOOPS | | 1 | 97 | 16 (0)| 00:00:01 |
| 5 | TABLE ACCESS BY INDEX ROWID | R_RAPPORT | 60730 | 5159K| 6 (0)| 00:00:01 |
| 6 | INDEX FULL SCAN DESCENDING | IDX_R_RAPPORT_3 | 10 | | 2 (0)| 00:00:01 |
|* 7 | INDEX RANGE SCAN | TEST5 | 1 | 10 | 1 (0)| 00:00:01 |
| 8 | NESTED LOOPS | | 1 | 25 | 2 (0)| 00:00:01 |
|* 9 | INDEX RANGE SCAN | TEST7 | 141 | 1269 | 2 (0)| 00:00:01 |
|* 10 | INDEX UNIQUE SCAN | TEST8 | 1 | 16 | 0 (0)| 00:00:01 |
|* 11 | TABLE ACCESS BY INDEX ROWID | R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 12 | NESTED LOOPS | | 2 | 88 | 35 (0)| 00:00:01 |
| 13 | NESTED LOOPS | | 10 | 210 | 7 (0)| 00:00:01 |
|* 14 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 15 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 16 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 17 | TABLE ACCESS BY INDEX ROWID| R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 18 | NESTED LOOPS | | 2 | 88 | 35 (0)| 00:00:01 |
| 19 | NESTED LOOPS | | 10 | 210 | 7 (0)| 00:00:01 |
|* 20 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 21 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 22 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 23 | INDEX RANGE SCAN | TEST6 | 1 | 8 | 8 (0)| 00:00:01 |
----------------------------------------------------------------------------------------------------------
Unfortunately this query is composed at runtime, and should there be three subrequests instead of the two here, it will ignore the FIRST_ROWS hint and again do multiple full table scans on 8 million rows. With the given data distribution access by rowid will always be faster (almost instant) while the plan Oracle prefers takes several seconds.
I tried using ROWID hints on both tables, before discovering those have been deprecated.
Any pointers will be appreciated.
=edit=
USE_NL & new Index
-----------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 101 | 22220 | 3994 (1)| 00:00:48 |
|* 1 | COUNT STOPKEY | | | | | |
| 2 | VIEW | | 102 | 22440 | 3994 (1)| 00:00:48 |
| 3 | NESTED LOOPS SEMI | | 1 | 102 | 16 (7)| 00:00:01 |
| 4 | NESTED LOOPS | | 1 | 97 | 11 (0)| 00:00:01 |
| 5 | TABLE ACCESS BY INDEX ROWID | R_RAPPORT | 58985 | 5011K| 10 (0)| 00:00:01 |
|* 6 | INDEX FULL SCAN DESCENDING | TEST12 | 1 | | 9 (0)| 00:00:01 |
|* 7 | TABLE ACCESS BY INDEX ROWID | R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 8 | NESTED LOOPS | | 2 | 88 | 35 (0)| 00:00:01 |
| 9 | NESTED LOOPS | | 10 | 210 | 7 (0)| 00:00:01 |
|* 10 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 11 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 12 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 13 | TABLE ACCESS BY INDEX ROWID| R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 14 | NESTED LOOPS | | 2 | 88 | 35 (0)| 00:00:01 |
| 15 | NESTED LOOPS | | 10 | 210 | 7 (0)| 00:00:01 |
|* 16 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 17 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 18 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 19 | INDEX RANGE SCAN | TEST6 | 1 | 8 | 8 (0)| 00:00:01 |
|* 20 | INDEX RANGE SCAN | TEST5 | 1 | 10 | 1 (0)| 00:00:01 |
|* 21 | VIEW | VW_NSO_1 | 105 | 525 | 5 (20)| 00:00:01 |
|* 22 | HASH JOIN | | 214 | 5350 | 5 (20)| 00:00:01 |
|* 23 | INDEX RANGE SCAN | TEST7 | 141 | 1269 | 2 (0)| 00:00:01 |
|* 24 | INDEX RANGE SCAN | TEST8 | 228 | 3648 | 2 (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------
SQL:
select /*+ FIRST_ROWS */ * from (
select *
from r_rapport a
where rb_id in (
select obj_id from obj_recht where obj_typ = 20 and obj_pid = 10065 and maske_id in (
select distinct maske_id
from obj_rechtmaske
where subj_pid = 10065
) )
and rb_id in (
select id from rb_buch where pid = 10065
)
and exists (
select /*+ USE_NL( c d ) */ 1
from r_teilanlage b, r_attribut c, r_attributfeld d
where a.id = b.r_id
and b.id = c.r_teilanlage_id
and c.id = d.r_attribut_id
and d.attributfeld_typ not in ( 20, 25, 40, 78, 79, 90, 92, 123, 124, 125, 126, 127 )
and lower( d.wert ) like lower( '%ä%' )
)
and exists (
select /*+ USE_NL( c d ) */ 1
from r_teilanlage b, r_attribut c, r_attributfeld d
where a.id = b.r_id
and b.id = c.r_teilanlage_id
and c.id = d.r_attribut_id
and d.attributfeld_typ not in ( 20, 25, 40, 78, 79, 90, 92, 123, 124, 125, 126, 127 )
and lower( d.wert ) like lower( '%ö%' )
)
and exists (
select /*+ USE_NL( c d ) */ 1
from r_teilanlage b, r_attribut c, r_attributfeld d
where a.id = b.r_id
and b.id = c.r_teilanlage_id
and c.id = d.r_attribut_id
and d.attributfeld_typ not in ( 20, 25, 40, 78, 79, 90, 92, 123, 124, 125, 126, 127 )
and lower( d.wert ) like lower( '%ä%' )
)
and exists (
select /*+ USE_NL( c d ) */ 1
from r_teilanlage b, r_attribut c, r_attributfeld d
where a.id = b.r_id
and b.id = c.r_teilanlage_id
and c.id = d.r_attribut_id
and d.attributfeld_typ not in ( 20, 25, 40, 78, 79, 90, 92, 123, 124, 125, 126, 127 )
and lower( d.wert ) like lower( '%ö%' )
)
and a.id not in (
select r_id from r_gelesen where ma_id = 144
)
order by a.open_stamp desc
) where rownum <= 101;
and its plan:
----------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 220 | 1195K (1)| 03:59:08 |
|* 1 | COUNT STOPKEY | | | | | |
| 2 | VIEW | | 1 | 220 | 1195K (1)| 03:59:08 |
|* 3 | FILTER | | | | | |
| 4 | NESTED LOOPS SEMI | | 3213 | 320K| 1018K (1)| 03:23:47 |
| 5 | NESTED LOOPS | | 6547 | 620K| 82249 (1)| 00:16:27 |
| 6 | TABLE ACCESS BY INDEX ROWID | R_RAPPORT | 60730 | 5159K| 21493 (1)| 00:04:18 |
| 7 | INDEX FULL SCAN DESCENDING | IDX_R_RAPPORT_3 | 60730 | | 152 (1)| 00:00:02 |
|* 8 | INDEX RANGE SCAN | TEST5 | 1 | 10 | 1 (0)| 00:00:01 |
|* 9 | VIEW | VW_NSO_1 | 105 | 525 | 143 (0)| 00:00:02 |
| 10 | NESTED LOOPS | | 214 | 5350 | 143 (0)| 00:00:02 |
|* 11 | INDEX RANGE SCAN | TEST7 | 141 | 1269 | 2 (0)| 00:00:01 |
|* 12 | INDEX RANGE SCAN | TEST8 | 2 | 32 | 1 (0)| 00:00:01 |
|* 13 | TABLE ACCESS BY INDEX ROWID | R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 14 | NESTED LOOPS | | 6 | 264 | 97 (0)| 00:00:02 |
| 15 | NESTED LOOPS | | 30 | 630 | 13 (0)| 00:00:01 |
|* 16 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 17 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 18 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 19 | TABLE ACCESS BY INDEX ROWID | R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 20 | NESTED LOOPS | | 6 | 264 | 97 (0)| 00:00:02 |
| 21 | NESTED LOOPS | | 30 | 630 | 13 (0)| 00:00:01 |
|* 22 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 23 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 24 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 25 | TABLE ACCESS BY INDEX ROWID | R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 26 | NESTED LOOPS | | 6 | 264 | 97 (0)| 00:00:02 |
| 27 | NESTED LOOPS | | 30 | 630 | 13 (0)| 00:00:01 |
|* 28 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 29 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 30 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 31 | TABLE ACCESS BY INDEX ROWID| R_ATTRIBUTFELD | 1 | 23 | 3 (0)| 00:00:01 |
| 32 | NESTED LOOPS | | 6 | 264 | 97 (0)| 00:00:02 |
| 33 | NESTED LOOPS | | 30 | 630 | 13 (0)| 00:00:01 |
|* 34 | INDEX RANGE SCAN | TEST4 | 9 | 90 | 3 (0)| 00:00:01 |
|* 35 | INDEX RANGE SCAN | TEST3 | 3 | 33 | 2 (0)| 00:00:01 |
|* 36 | INDEX RANGE SCAN | IDX_R_ATTRIBUTFELD_1 | 6 | | 2 (0)| 00:00:01 |
|* 37 | INDEX RANGE SCAN | TEST6 | 1 | 8 | 8 (0)| 00:00:01 |
----------------------------------------------------------------------------------------------------------
A horrible, horrible cost estimate as this query completes instantly.
If you want to avoid table access full on r_attributfeld, you should try a nested loop on this table.
Maybe you'll have to had a leading(r_rapport r_attributfeld) (or ordered hint) if Oracle "don't understand" what you want
Not always what you think is better plan is realy better plan. To return you first rows fast is right way to use nested loops and rowid acces. But if you want return all result set fast it is more efficient to use hash join even if you are joining by rowid("select * from tab where rowid in (...)" or "... join tab on tab.rowid = ...'). So I think Oracle picked right plan for you.
we are facing issue with one of query which joins between few tables.
even though there are few hundreds of records in the table the plan is going to Merge join thinking only one record in the table, please find the below plan.
when the Merge sort plan is used the query fails with temp space issue.
oracle choose Merge plan only when job loaded to newly created partition. but the rest of old partitions it is choosing Hash Join where we get results in few seconds.
for information. All the joined table has same volume.
could you please explain why this is happening?
Merg join( query hung)
-----------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
-----------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 712 | 36 (3)| 00:00:01 | | |
|* 1 | HASH JOIN | | 1 | 712 | 36 (3)| 00:00:01 | | |
| 2 | MERGE JOIN CARTESIAN | | 1 | 679 | 28 (0)| 00:00:01 | | |
| 3 | MERGE JOIN CARTESIAN | | 1 | 615 | 21 (0)| 00:00:01 | | |
| 4 | MERGE JOIN CARTESIAN | | 1 | 388 | 14 (0)| 00:00:01 | | |
| 5 | PARTITION RANGE SINGLE | | 1 | 105 | 7 (0)| 00:00:01 | 4 | 4 |
|* 6 | TABLE ACCESS FULL | PCA_DCM_CLNT_BSPKE_REFS_M_LND | 1 | 105 | 7 (0)| 00:00:01 | 4 | 4 |
| 7 | BUFFER SORT | | 1 | 283 | 7 (0)| 00:00:01 | | |
| 8 | PARTITION RANGE SINGLE| | 1 | 283 | 7 (0)| 00:00:01 | 4 | 4 |
|* 9 | TABLE ACCESS FULL | PCA_DCM_INDBTDNS_BLK_M_LND | 1 | 283 | 7 (0)| 00:00:01 | 4 | 4 |
| 10 | BUFFER SORT | | 1 | 227 | 14 (0)| 00:00:01 | | |
| 11 | PARTITION RANGE SINGLE | | 1 | 227 | 7 (0)| 00:00:01 | 4 | 4 |
|* 12 | TABLE ACCESS FULL | PCA_DCM_DELPHI_BLK_M_LND | 1 | 227 | 7 (0)| 00:00:01 | 4 | 4 |
| 13 | BUFFER SORT | | 1 | 64 | 21 (0)| 00:00:01 | | |
| 14 | PARTITION RANGE SINGLE | | 1 | 64 | 7 (0)| 00:00:01 | 4 | 4 |
|* 15 | TABLE ACCESS FULL | PCA_DCM_APACS_BLK_M_LND | 1 | 64 | 7 (0)| 00:00:01 | 4 | 4 |
| 16 | PARTITION RANGE SINGLE | | 1 | 33 | 7 (0)| 00:00:01 | 4 | 4 |
|* 17 | TABLE ACCESS FULL | PCA_DCM_SCORE_BLK_M_LND | 1 | 33 | 7 (0)| 00:00:01 | 4 | 4 |
-----------------------------------------------------------------------------------------------------------------------------
Hash join(Few seconds we get the results)
----------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
----------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 491 | 341K| 74 (3)| 00:00:01 | | |
|* 1 | HASH JOIN | | 491 | 341K| 74 (3)| 00:00:01 | | |
| 2 | PARTITION RANGE SINGLE | | 493 | 109K| 14 (0)| 00:00:01 | 3 | 3 |
|* 3 | TABLE ACCESS FULL | PCA_DCM_DELPHI_BLK_M_LND | 493 | 109K| 14 (0)| 00:00:01 | 3 | 3 |
|* 4 | HASH JOIN | | 491 | 232K| 60 (4)| 00:00:01 | | |
|* 5 | HASH JOIN | | 492 | 99384 | 45 (3)| 00:00:01 | | |
|* 6 | HASH JOIN | | 492 | 47724 | 31 (4)| 00:00:01 | | |
| 7 | PARTITION RANGE SINGLE| | 493 | 16269 | 14 (0)| 00:00:01 | 3 | 3 |
|* 8 | TABLE ACCESS FULL | PCA_DCM_SCORE_BLK_M_LND | 493 | 16269 | 14 (0)| 00:00:01 | 3 | 3 |
| 9 | PARTITION RANGE SINGLE| | 493 | 31552 | 16 (0)| 00:00:01 | 3 | 3 |
|* 10 | TABLE ACCESS FULL | PCA_DCM_APACS_BLK_M_LND | 493 | 31552 | 16 (0)| 00:00:01 | 3 | 3 |
| 11 | PARTITION RANGE SINGLE | | 493 | 51765 | 14 (0)| 00:00:01 | 3 | 3 |
|* 12 | TABLE ACCESS FULL | PCA_DCM_CLNT_BSPKE_REFS_M_LND | 493 | 51765 | 14 (0)| 00:00:01 | 3 | 3 |
| 13 | PARTITION RANGE SINGLE | | 493 | 136K| 14 (0)| 00:00:01 | 3 | 3 |
|* 14 | TABLE ACCESS FULL | PCA_DCM_INDBTDNS_BLK_M_LND | 493 | 136K| 14 (0)| 00:00:01 | 3 | 3 |
----------------------------------------------------------------------------------------------------------------------------
Please find the query
SELECT
substr(BLK.ACC_NUM,1,14) AS ACCOUNT_NUMBER,
CASE WHEN SUBSTR(BLK.ACC_NUM,20,1) = '1' THEN 'F1'
WHEN SUBSTR(BLK.ACC_NUM,20,1) = ' ' THEN 'F1'
WHEN SUBSTR(BLK.ACC_NUM,20,1) = '0' THEN 'F1'
WHEN SUBSTR(BLK.ACC_NUM,20,1) = '2' THEN 'F2'
END FLTR,
DELPHI.ND_SPA_CII_SPA
FROM
BUR_LND.PCA_DCM_SCORE_BLK_M_LND BLK
INNER JOIN BUR_LND.PCA_DCM_CLNT_BSPKE_REFS_M_LND REFFS
ON BLK.ACC_NUM= REFFS.ACC_NUM
INNER JOIN BUR_LND.PCA_DCM_INDBTDNS_BLK_M_LND IND
ON BLK.ACC_NUM= IND.ACC_NUM
INNER JOIN BUR_LND.PCA_DCM_DELPHI_BLK_M_LND DELPHI
ON BLK.ACC_NUM= DELPHI.ACC_NUM
INNER JOIN BUR_LND.PCA_DCM_APACS_BLK_M_LND APACS
ON BLK.ACC_NUM= APACS.ACC_NUM
WHERE
BLK.EFF_DT=TO_DATE('2013-10-30','YYYY-MM-DD')
AND REFFS.EFF_DT=TO_DATE('2013-10-30','YYYY-MM-DD')
AND IND.EFF_DT=TO_DATE('2013-10-30','YYYY-MM-DD')
AND DELPHI.EFF_DT=TO_DATE('2013-10-30','YYYY-MM-DD')
AND APACS.EFF_DT=TO_DATE('2013-10-30','YYYY-MM-DD')
Thanks in advance for help.
Thanks
arkesh
The plans are bad because the new partition is missing statistics. Statistics should be updated after partition changes, ideally using incremental statistics. If that's not possible then a hint like /*+ dynamic_sampling(4) */ can help.
Statistics can be accurate, inaccurate, or missing. Missing statistics are generally not a huge problem because of dynamic sampling. With the default dynamic sampling level, 2, Oracle will automatically gather statistics if a statement includes tables without statistics.
Unfortunately for this case, Oracle only considers missing statistics per table, not per partition. (That would be a good feature request, but that won't help you right now.) With the literals in the SQL statement Oracle appears to know exactly which partition to look in. Since there are no statistics for that partition it assumes there are no rows, leading to the bad plans.
Example
Create a sample partitioned table with 1000 rows but no gathered statistics.
create table partition_test
(
a number,
b number
)
partition by range (a)
(
partition p1 values less than (2)
);
insert into partition_test select 1, level from dual connect by level <= 1000;
When there are no statistics Oracle will use dynamic sampling automatically and get a good row count. You can't see it in this simple plan, but normally this would lead to better access methods and better join operations.
explain plan for select * from partition_test where a = 1 and b <= 1000;
select * from table(dbms_xplan.display);
Plan hash value: 4097357352
---------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
---------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1000 | 26000 | 16 (0)| 00:00:01 | | |
| 1 | PARTITION RANGE SINGLE| | 1000 | 26000 | 16 (0)| 00:00:01 | 1 | 1 |
|* 2 | TABLE ACCESS FULL | PARTITION_TEST | 1000 | 26000 | 16 (0)| 00:00:01 | 1 | 1 |
---------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("A"=1 AND "B"<=1000)
Note
-----
- dynamic statistics used: dynamic sampling (level=2)
Gather stats, then create a new partition with data. Although that partition has 1000 rows and no stats, Oracle does not know that and just assumes it's empty.
begin
dbms_stats.gather_table_stats(user, 'partition_test');
end;
/
alter table partition_test add partition p2 values less than (3);
insert into partition_test select 2, level from dual connect by level <= 1000;
explain plan for select * from partition_test where a = 2 and b <= 1000;
select * from table(dbms_xplan.display);
Plan hash value: 4097357352
---------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
---------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 7 | 9 (0)| 00:00:01 | | |
| 1 | PARTITION RANGE SINGLE| | 1 | 7 | 9 (0)| 00:00:01 | 2 | 2 |
|* 2 | TABLE ACCESS FULL | PARTITION_TEST | 1 | 7 | 9 (0)| 00:00:01 | 2 | 2 |
---------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("A"=2 AND "B"<=1000)
Explicitly requesting dynamic sampling will fix the cardinality estimates, which would likely solve your execution plan problems.
explain plan for select /*+ dynamic_sampling(4) */ * from partition_test where a = 2 and b <= 1000;
select * from table(dbms_xplan.display);
Plan hash value: 4097357352
---------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop |
---------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1000 | 7000 | 9 (0)| 00:00:01 | | |
| 1 | PARTITION RANGE SINGLE| | 1000 | 7000 | 9 (0)| 00:00:01 | 2 | 2 |
|* 2 | TABLE ACCESS FULL | PARTITION_TEST | 1000 | 7000 | 9 (0)| 00:00:01 | 2 | 2 |
---------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - filter("A"=2 AND "B"<=1000)
Note
-----
- dynamic statistics used: dynamic sampling (level=4)
Sorry for my English.
I have so big DB on Oracle 10g.
And I have queries, which executed so slow. For example, I have query :
115559 rows – 102 seconds
Execution plan:
Plan hash value: 3664903106
------------------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |
------------------------------------------------------------------------------------------------------------------------------------------------
| 1 | SORT ORDER BY | | 1 | 30503 | 50 |00:00:09.33 | 3989 | 33M| 2065K| 29M (0)|
|* 2 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:05.71 | 3989 | 862K| 862K| 1186K (0)|
| 3 | INDEX FAST FULL SCAN | IX2_SLCND | 1 | 1387 | 1387 |00:00:00.01 | 17 | | | |
|* 4 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:05.47 | 3972 | 785K| 785K| 1145K (0)|
| 5 | TABLE ACCESS FULL | DISC | 1 | 90 | 90 |00:00:00.01 | 7 | | | |
|* 6 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:05.24 | 3965 | 776K| 776K| 403K (0)|
| 7 | VIEW | index$_join$_030 | 1 | 2 | 2 |00:00:00.01 | 6 | | | |
|* 8 | HASH JOIN | | 1 | | 2 |00:00:00.01 | 6 | 760K| 760K| 464K (0)|
| 9 | INDEX FAST FULL SCAN | IX_CMP_NAME | 1 | 2 | 2 |00:00:00.01 | 3 | | | |
| 10 | INDEX FAST FULL SCAN | PK_CMP | 1 | 2 | 2 |00:00:00.01 | 3 | | | |
|* 11 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:05.01 | 3959 | 756K| 756K| 1066K (0)|
| 12 | TABLE ACCESS FULL | TTYPE | 1 | 26 | 27 |00:00:00.01 | 7 | | | |
|* 13 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:04.78 | 3952 | 767K| 767K| 416K (0)|
| 14 | TABLE ACCESS FULL | COMMTCOMP | 1 | 2 | 2 |00:00:00.01 | 7 | | | |
|* 15 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:04.54 | 3945 | 760K| 760K| 1037K (0)|
| 16 | TABLE ACCESS FULL | TTYPE | 1 | 26 | 27 |00:00:00.01 | 7 | | | |
|* 17 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:04.31 | 3938 | 842K| 842K| 1267K (0)|
| 18 | TABLE ACCESS FULL | SLRSSEASONTC | 1 | 2885 | 2974 |00:00:00.01 | 53 | | | |
|* 19 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:04.07 | 3885 | 909K| 909K| 1178K (0)|
| 20 | TABLE ACCESS FULL | CAR | 1 | 976 | 976 |00:00:00.01 | 16 | | | |
|* 21 | HASH JOIN RIGHT OUTER | | 1 | 30503 | 115K|00:00:03.84 | 3869 | 1036K| 1036K| 1169K (0)|
| 22 | INDEX FULL SCAN | PK_STP | 1 | 258 | 258 |00:00:00.01 | 1 | | | |
|* 23 | HASH JOIN | | 1 | 30503 | 115K|00:00:03.60 | 3868 | 778K| 778K| 1165K (0)|
| 24 | TABLE ACCESS FULL | WKST | 1 | 83 | 83 |00:00:00.01 | 7 | | | |
|* 25 | HASH JOIN | | 1 | 61027 | 115K|00:00:03.37 | 3861 | 804K| 804K| 924K (0)|
| 26 | VIEW | index$_join$_014 | 1 | 12 | 12 |00:00:00.01 | 6 | | | |
|* 27 | HASH JOIN | | 1 | | 12 |00:00:00.01 | 6 | 783K| 783K| 919K (0)|
| 28 | INDEX FAST FULL SCAN | IX_BRANCH_NAME | 1 | 12 | 12 |00:00:00.01 | 3 | | | |
| 29 | INDEX FAST FULL SCAN | PK_BRANCH | 1 | 12 | 12 |00:00:00.01 | 3 | | | |
|* 30 | HASH JOIN | | 1 | 61027 | 115K|00:00:03.13 | 3855 | 808K| 808K| 1166K (0)|
| 31 | TABLE ACCESS FULL | USERS | 1 | 96 | 96 |00:00:00.01 | 16 | | | |
| 32 | MERGE JOIN | | 1 | 115K| 115K|00:00:02.90 | 3839 | | | |
|* 33 | HASH JOIN RIGHT OUTER| | 1 | 115K| 115K|00:00:02.32 | 3838 | 848K| 848K| 1169K (0)|
| 34 | TABLE ACCESS FULL | STP | 1 | 258 | 258 |00:00:00.01 | 7 | | | |
|* 35 | HASH JOIN | | 1 | 115K| 115K|00:00:01.95 | 3831 | 848K| 848K| 1169K (0)|
| 36 | TABLE ACCESS FULL | STP | 1 | 258 | 258 |00:00:00.01 | 7 | | | |
|* 37 | HASH JOIN | | 1 | 115K| 115K|00:00:01.52 | 3824 | 848K| 848K| 1169K (0)|
| 38 | TABLE ACCESS FULL | STP | 1 | 258 | 258 |00:00:00.01 | 7 | | | |
|* 39 | HASH JOIN | | 1 | 115K| 115K|00:00:01.09 | 3817 | 10M| 1956K| 12M (0)|
|* 40 | TABLE ACCESS FULL| SL | 1 | 116K| 120K|00:00:00.01 | 2115 | | | |
|* 41 | TABLE ACCESS FULL| SLTC | 1 | 114K| 115K|00:00:00.19 | 1702 | | | |
|* 42 | SORT JOIN | | 115K| 1 | 115K|00:00:00.27 | 1 | 73728 | 73728 | |
|* 43 | INDEX UNIQUE SCAN | PK_CMP | 1 | 1 | 1 |00:00:00.01 | 1 | | | |
------------------------------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
2 - access("SLCND"."ID"="SL"."ID")
4 - access("SL"."DISC_ID"="DISC"."ID")
6 - access("CARI"."ID"="SLTC"."CARI_ID")
8 - access(ROWID=ROWID)
11 - access("TTYPE"."ID"="SLTC"."TTYPE_ID")
13 - access("CTC"."ID"="SLRSSEASONTC "."ID_COMMTCOMP")
15 - access("RS"."ID"="SLRSSEASONTC "."COMMTTYPE_ID")
17 - access("SLRSSEASONTC "."ID"="SLTC"."ID")
19 - access("CAR"."ID"="SLTC"."CAR_ID")
21 - access("STP"."ID"="WKST"."DEF_STP_ID")
23 - access("SL"."POS_WKST_ID"="WKST"."ID")
25 - access("USERS"."BRANCH_ID"="BRANCH"."ID")
27 - access(ROWID=ROWID)
30 - access("SL"."USR_CAS_ID"="USERS"."ID")
33 - access("SLTC"."THSTP_ID"="THSTP"."ID")
35 - access("SLTC"."TSTP_ID"="TSTP"."ID")
37 - access("SLTC"."FSTP_ID"="FSTP"."ID")
39 - access("SLTC"."ID"="SL"."ID")
40 - filter(("SL"."WHEN_DATE">=TO_DATE('2001-10-29 00:00:00', 'yyyy-mm-dd hh24:mi:ss') AND "SL"."SCOMP_ID"=1 AND
"SL"."WHEN_DATE"<=TO_DATE('2013-10-29 23:59:59', 'yyyy-mm-dd hh24:mi:ss')))
41 - filter("SLTC"."MANUAL"='N')
42 - access("SL"."SCOMP_ID"="CMP"."ID")
filter("SL"."SCOMP_ID"="CMP"."ID")
43 - access("CMP"."ID"=1)
I need ideas to make db faster.
Thanks You!
p.s.
I’m new in databases
So yeah, a you have a pretty horrible execution plan there.
To optimise the query, we would need the query as well, but I'll try to give you a few hints using just your exection plan output.
See all the TABLE ACCESS FULL? This is what usually takes time! Try using indexes on your tables, it seems that there are too few indexes used here (probably because no other indexes exist). Based on the execution plan, here are some simple indexes that might work, you may try them out:
CREATE INDEX ix_sltc_id ON sltc(ID);
CREATE INDEX ix_sl_id ON sl(ID);
CREATE INDEX ix_sltc_manual ON sltc(manual);
CREATE INDEX ix_sl_scomp_id ON sl(SCOMP_ID);
CREATE INDEX ix_sl_pos_wkst_id ON sl(POS_WKST_ID);
CREATE INDEX ix_sltc_thstp_id ON sltc(THSTP_ID)
CREATE INDEX ix_sltc_thstp_id ON sltc(THSTP_ID);
CREATE INDEX ix_sltc_tstp_id ON sltc(TSTP_ID);
CREATE INDEX ix_sltc_fstp_id ON sltc(FSTP_ID);
Without the query itself, we are quite limited here and probably missing most of the picture. Using the query, we could then try to create composite indexes, that are much more efficient.
More importantly, it seems that you do not use PRIMARY KEYs on your tables, because there are a lot of TABLE ACCESS FULL operations on tables with the predicate "ID". Make sure all your "ID" columns are indexed as well (or defined as PRIMARY KEY if that is indeed the primary key).
Also, we see that the optimizer does not have correct statistics, try to manually refresh the statistics for your schema:
EXEC DBMS_STATS.delete_schema_stats('SCOTT');
And as a sidenote: Whoever designed this schema, educate this person on database design!
Another sidenote for the more advanced readers: While TABLE ACCESS FULL is not always bad (there are quite a few cases where a full table scan is faster than access via indexes), it often indicates missing indexes. So setting the indexes and refreshing the statistics should provide a performance gain here.