Optimize long running select query against Oracle database - sql

Question

I'm not an DBA expert, we have an existing Oracle query to extract data for a particular day , the problem we've is if the business volume for a day is extremly large, the query takes 8+ hours and timedout. We cannot do optimization inside the database itself, then how do we usually handle extreme case like this? I've pasted the query below with content masked to show the SQL structure, looking for advises on how to optimizae this query or any alternative way to avoid timeout.
WHENEVER SQLERROR EXIT 1
SET LINESIZE 9999
SET ECHO OFF
SET FEEDBACK OFF
SET PAGESIZE 0
SET HEADING OFF
SET TRIMSPOOL ON
SET COLSEP ","
SELECT co.cid
|| ',' || DECODE(co.cid,'xxxxx','xxxx',null,'N/A','xxxxx')
|| ',' || d.name
|| ',' || ti.rc
|| ',' || DECODE(cf.side_id,1,'x',2,'xx',5,'xx','')
|| ',' || cf.Quantity
|| ',' || cf.price
|| ',' || TO_CHAR(time,'YYYY-mm-dd hh24:mi:ss')
|| ',' || DECODE(co.capacity_id,1,'xxxx',2,'xxxx','')
|| ',' || co.type
|| ',' || cf.id
|| ',' || CASE
WHEN (cf.account_id = xxx OR cf.account_id = xxx) THEN SUBSTR(cf.tag, 1, INSTR(cf.tag, '.')-1) || '_' || ti.ric || '_' || DECODE(cf.side_id,1,'xx',2,'xx',5,'xx','')
WHEN INSTR(cf.clientorder_id, '#') > 0 THEN SUBSTR(cf.clientorder_id, 1, INSTR(cf.clientorder_id, '#')-1)
ELSE cf.clientorder_id
END
|| ',' || co.tag
|| ',' || t.description
|| ',' || CASE
WHEN cf.id = xxx THEN 'xxxx'
ELSE (SELECT t.name FROM taccount t WHERE t.account_id = cf.account_id)
END as Account
FROM clientf cf, tins ti, thistory co, tdk d, tra t
WHERE cf.sessiondate = TO_DATE('xxxxxx','YYYYMMDD')
AND cf.orderhistory_id = co.orderhistory_id
AND cf.reporttype_id = 1
AND ti.inst_id = cf.inst_id
AND (ti.rc LIKE '%.xx' or ti.rc LIKE '%.xx' or ti.rc LIKE '%.xx' )
AND d.de_id = t.de_id
AND t.tr_id = co.tr_id
AND nvl(co.type_id,0) <> 3
AND cf.trid not in (SELECT v2.pid FROM port v2 WHERE v2.sessiondate = cf.sessiondate AND v2.exec_id = 4)
ORDER BY co.cid, time, cf.quantity;

Answer 1

I would firstly talk to the people who need the output of this query and ask them about the report and each individual column. Sometimes, some columns are not needed any more, sometimes the whole report. 8+ hours runtime is a good bargaining point ;-)
Next, I would put the original query to one side and start build an test query from scratch, bit by bit, for instance starting with clientf, taking all it's columns in the WHERE clause:
SELECT *
FROM clientf SAMPLE (0.1) cf
WHERE cf.sessiondate = TO_DATE('xxxxxx','YYYYMMDD')
AND cf.reporttype_id = 1;
If that's ok, I'd increase the sample size until 99%. If the runtime is already to long, you might suggest an index on clientf.sessiondate (or may be on clientf.reporttype_id, but that's unlikely helpful as it looks like to have too few distinct values).
Once that is done, I'd join the first table:
SELECT *
FROM clientf SAMPLE (0.1) cf
WHERE cf.sessiondate = TO_DATE('xxxxxx','YYYYMMDD')
AND cf.reporttype_id = 1
AND cf.trid NOT IN (SELECT v2.pid
FROM port v2
WHERE v2.sessiondate = cf.sessiondate
AND v2.exec_id = 4);
I'd compare NOT IN and WHERE NOT EXISTS, not expecting much differences.
Then I'd join the next table (prefering personally ANSI syntax), again starting with a small sample, again adding it's columns to the where clause:
SELECT *
FROM clientf SAMPLE (0.1) cf
FROM thistory co
ON cf.orderhistory_id = co.orderhistory_id
WHERE cf.sessiondate = TO_DATE('xxxxxx','YYYYMMDD')
AND cf.reporttype_id = 1
AND nvl(co.type_id,0) <> 3
AND cf.trid NOT IN (SELECT v2.pid
FROM port v2
WHERE v2.sessiondate = cf.sessiondate
AND v2.exec_id = 4);
I'd play around replacing nvl(co.type_id,0)<>3 with (co.type_id <>3 OR co.type_id IS NULL), monitoring carefully that the result is logically the same.
And so on...