Selecting a column goes for a full table scan

Question

Hi,
Oracle version 10.2
I have the below query:
SELECT   c.companyid,
         c.contactid,
         c.contactlname
    FROM contact c,company ic
   WHERE UPPER((c.contactlname)) LIKE CASE
           WHEN 'test' IS NULL THEN
            UPPER((c.contactlname))
           ELSE DECODE(1,
                   1,
                   '%' || 'TEST' || '%',
                   2,
                   'TEST' || '%',
                   3,
                   '%' || 'TEST',
                   4,
                   'TEST')
         END
     AND c.activeflag = DECODE('Y', 'N', 'Y', c.activeflag)
     AND ic.companyid=c.companyidthis is using the index on table company.
Explain plan:
SELECT STATEMENT, GOAL = ALL_ROWS               68     3523     176150     
NESTED LOOPS               68     3523     176150     
  TABLE ACCESS FULL          CONTACT     65     3523     155012     
  INDEX UNIQUE SCAN          COMPANY_PK     0     1     6          Now if i include two more columns from the company table in the select statement the plan changes and it goes for a full table scan...
Query:
SELECT   ic.companyname,
         ic.companystatustypeid,
         c.companyid,
         c.contactid,
         c.contactlname
    FROM contact c,company ic
   WHERE UPPER((c.contactlname)) LIKE CASE
           WHEN 'test' IS NULL THEN
            UPPER((c.contactlname))
           ELSE DECODE(1,
                   1,
                   '%' || 'TEST' || '%',
                   2,
                   'TEST' || '%',
                   3,
                   '%' || 'TEST',
                   4,
                   'TEST')
         END
     AND c.activeflag = DECODE('Y', 'N', 'Y', c.activeflag)
     AND ic.companyid=c.companyidExplain Plan:
SELECT STATEMENT, GOAL = ALL_ROWS               2126     4121     403858     
HASH JOIN               2126     4121     403858     
  TABLE ACCESS FULL          CONTACT     108     4121     185445     
  PARTITION LIST ALL               1959     1031340     54661020     
   TABLE ACCESS FULL          COMPANY     1959     1031340     54661020     Any ideas why?

Answer 1

dont think so.
i tried removing the filters also:
Query:
SELECT  -- ic.companyname,
       --  ic.companystatustypeid,
c.companyid,
         c.contactid,
         c.contactlname,
         c.contactfname,
         c.contactpositionid,
         c.contactroledesc,
         c.updateddate
    FROM contact c,company ic
   WHERE ic.companyid=c.companyidplan:
SELECT STATEMENT, GOAL = ALL_ROWS               109     73346     3520608     
NESTED LOOPS               109     73346     3520608     
  TABLE ACCESS FULL          CONTACT     51     73346     3080532     
  INDEX UNIQUE SCAN          COMPANY_PK     0     1     6     Query:
SELECT   ic.companyname,
         ic.companystatustypeid,
c.companyid,
         c.contactid,
         c.contactlname,
         c.contactfname,
         c.contactpositionid,
         c.contactroledesc,
         c.updateddate
    FROM contact c,company ic
   WHERE ic.companyid=c.companyid
     Plan:
SELECT STATEMENT, GOAL = ALL_ROWS               2462     73346     6894524     
HASH JOIN               2462     73346     6894524     
  TABLE ACCESS FULL          CONTACT     51     73346     3080532     
  PARTITION LIST ALL               1348     973674     50631048     
   TABLE ACCESS FULL          COMPANY     1348     973674     50631048     Does the columns selected have an impact on the plan?? I thought the plan is derived on basis of the join conditions...