RE: indexes

From: Kirsh, Gary <gary.kirsh_at_gs.com>
Date: Tue, 9 May 2000 11:16:33 -0400
Message-Id: <10492.105243@fatcity.com>

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Valerie,

I believe it can use the A column of the index, but not the C column, so depending on how selective A is, this may or may not be a good thing.

Gary

Gary Kirsh
Next Extent, Inc.

-----Original Message-----
From: Webber Valerie H [mailto:Valerie.H.Webber_at_irs.gov] Sent: Tuesday, May 09, 2000 11:10 AM
To: Multiple recipients of list ORACLE-L Subject: indexes

I know this issue has been discussed before but I can't find the answer in my list archives.

If you have a composite index on a table consisting of columns A,B,C in that order, will the index be used if I have a query/where clause on columns A and C?

I know that it will if I query on A alone or A,B or A,B,C but I can't find documentation about A and C (no B)

Thanks in advance!
Val

Valerie H. Webber
Management Systems Designers, Inc
Valerie.H.Webber_at_m1.irs.gov
704-569-1002 x107

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<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=582241415-09052000>Valerie,</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=582241415-09052000></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=582241415-09052000>I
believe it can use the A column of the index, but not the C column, so depending on how selective A is, this may or may not be a good thing.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=582241415-09052000></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=582241415-09052000>Gary</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=582241415-09052000></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=582241415-09052000>Gary
Kirsh</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff face=Arial size=2><SPAN class=582241415-09052000>Next
Extent, Inc.</SPAN></FONT></DIV>
<BLOCKQUOTE>

<DIV align=left class=OutlookMessageHeader dir=ltr><FONT face=Tahoma size=2>-----Original Message-----<BR><B>From:</B> Webber Valerie H [mailto:Valerie.H.Webber_at_irs.gov]<BR><B>Sent:</B> Tuesday, May 09, 2000 11:10 AM<BR><B>To:</B> Multiple recipients of list ORACLE-L<BR><B>Subject:</B> indexes<BR><BR></DIV></FONT>
<P><FONT color=#800000 face="Bookman Old Style">I know this issue has been discussed before but I can't find the answer in my list archives.</FONT> </P> <P><FONT color=#800000 face="Bookman Old Style">If you have a composite index on a table consisting of columns A,B,C in that order, will the index be used if I have a query/where clause on columns A and C?</FONT></P> <P><FONT color=#800000 face="Bookman Old Style">I know that it will if I query on A alone or A,B or A,B,C but I can't find documentation about A and C (no B)</FONT> </P>

  <P><FONT color=#800000 face="Bookman Old Style">Thanks in advance!</FONT> 
  <BR><FONT color=#800000 face="Bookman Old Style">Val</FONT> </P>
  <P><B><I><FONT color=#000080 face="Bookman Old Style">Valerie H.

Webber</FONT></I></B><I></I><FONT color=#000000 face=Arial><BR></FONT><FONT color=#000080 face="Comic Sans MS" size=1>Management Systems Designers, Inc</FONT><FONT color=#000000 face=Arial><BR></FONT><FONT color=#000080 face="Comic Sans MS" size=1>Valerie.H.Webber_at_m1.irs.gov</FONT><FONT color=#000000 face=Arial><BR></FONT><FONT color=#000080 face="Comic Sans MS" size=1>704-569-1002 x107</FONT><FONT color=#000000 face=Arial> Received on Tue May 09 2000 - 10:16:33 CDT