(1) Operation : SORT UNIQUE Cause : DISTINCT Clause, and IN sub-query where subquery is independent meand no co-relation with parenst query. If for IN subquery, there is an unique index on selected columns then SORT UNIQUE can be avoided. (2) Operation : SORT AGGREGATE Cause : Whenever u use group functions. It does not…
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select a.ksppinm “Parameter”, b.ksppstvl “Session Value”, c.ksppstvl “Instance Value” from x$ksppi a, x$ksppcv b, x$ksppsv c where a.indx = b.indx and a.indx = c.indx and substr(ksppinm,1,1)=’_’ order by a.ksppinm;
spool badsql5 set lines 132 set pages 300 col USR format a14 col PAR heading “Parsing ID” format 9999999 col ELA heading “ELP time(Sec)” format 9999999.0 col HASH heading “Hash Value” col USR heading “Parsing User” col T heading “SQL Text having Elapsed time > 1 sec” break on HASH on USR on ELA skip…
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Histograms ========== For uniformly distributed data, the cost-based approach makes fairly accurate guesses at the cost of executing a particular statement. However, when the data is not uniformly distributed, the optimizer cannot accurately estimate the selectivity of a query. Beginning in release 7.3, for columns which do not have uniform data distribution, Oracle will allow…
Note:102334.1 Subject: How to Automate Change Based Statistic Gathering – Monitoring Tables
select /*+ USE_NL(A,B) INDEX(a ATS_FLORIST_FITTYPE_I)*/ a.FIT_ID from ATS_FLORISTS a,ATS_FLORISTS_TRACKING b where b.FIN_PROC = ‘N’ AND b.OLD_FRESH_PAY = ‘Y’ and b.NEW_FRESH_PAY=’N’ and a.FIT_TYPE=’P’ and a.ID= b.fit_id
If your index is NONUNIQUE, you cant enforce Index Unique Scan.
One test case today i found with copy command. When we are using sqlplus copy command with “APPEND” clause, and if source table contains any NUMBER datatype without Precision and Scale, then COPY statement fails with error indicating “NUMERIC ERROR and Number data type precision is higher than 38 digit”.
