Btmap Index

From: Krishna Prasad <krishna_at_nehanet.com>
Date: Mon, 8 Jan 2001 14:44:59 -0800
Message-Id: <10735.126066@fatcity.com>

This is a multi-part message in MIME format.

------=_NextPart_000_0034_01C07981.936F2250 Content-Type: text/plain;

charset="iso-8859-1"
Content-Transfer-Encoding: 8bit

RE: Date comparison questionHi,

Is there any init.ora parameter that needs to be turned to activate bitmap indexes?
I have a bitmap index on one column C1, but when i examine the explain pan of the
query: " select C1, b, c from table TT where C1 in ('dd','ff')" , it looks like it is not using
the index but doing a full table scan...

thanks
-krishna
  -----Original Message-----
  From: root_at_fatcity.com [mailto:root_at_fatcity.com]On Behalf Of Jacques Kilchoer
  Sent: Monday, January 08, 2001 2:01 PM   To: Multiple recipients of list ORACLE-L   Subject: RE: Date comparison question

> -----Original Message-----
> From: Lisa Yates [mailto:cosnit_at_creighton.edu]
> Sent: lundi, 8. janvier 2001 11:27
>
> Why doesn't this query ever return...
>
> where run_date = to_date('01-03-2001 16:34:59','mm-dd-yyyy
> hh24:mi:ss')
>
> but this query does....
>
> where to_char(run_date) = to_char(to_date('01-03-2001
> 16:34:59','mm-dd-yyyy hh24:mi:ss'))
>
> and so does this query....
>
> where to_char(run_date,'mm-dd-yyyy hh24:mi:ss') = '01-03-2001
> 16:34:59'

Well, I guess my suggestion that run_date may contain a "BCE" (before common era) date was not the answer to your problem. Maybe I misunderstood the issue. When you say "why doesn't the query ever return", do you mean it returns zero rows, or do you mean that the query is taking an abnormally long time? If it's taking an abnormally long time, an explain plan on the two queries may reveal the cause.

  Jacques R. Kilchoër
  (949) 754-8816
  Quest Software, Inc.

  8001 Irvine Center Drive
  Irvine, California 92618
  U.S.A.
  http://www.quest.com

------=_NextPart_000_0034_01C07981.936F2250 Content-Type: text/html;

charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD><TITLE>RE: Date comparison question</TITLE>
<META content=3D"text/html; charset=3Diso-8859-1" =

http-equiv=3DContent-Type>

<META content=3D"MSHTML 5.00.2920.0" name=3DGENERATOR></HEAD>
<BODY>
<DIV><FONT color=3D#0000ff face=3DArial size=3D2><SPAN=20

class=3D953563822-08012001>Hi,</DIV> <DIV><SPAN=20 class=3D953563822-08012001> </DIV> <DIV>Is=20
there any init.ora parameter that needs to be turned to activate bitmap=20 indexes?</DIV>
<DIV>I have=20
a bitmap index on one column C1, but when i examine the explain pan = of the=20
</DIV>
<DIV>query:=20
" select C1, b, c from table TT where C1 in ('dd','ff')" , it = looks=20
like it is not using</DIV> <DIV>the=20
index but doing a full table scan...</DIV> <DIV><SPAN=20 class=3D953563822-08012001> </DIV> <DIV><SPAN=20 class=3D953563822-08012001>thanks</DIV> <DIV><SPAN=20 class=3D953563822-08012001>-krishna</DIV> <BLOCKQUOTE style=3D"MARGIN-RIGHT: 0px"> <DIV align=3Dleft class=3DOutlookMessageHeader dir=3Dltr>-----Original Message----- From: root_at_fatcity.com=20 [mailto:root_at_fatcity.com]On Behalf Of Jacques = Kilchoer Sent:=20
 Monday, January 08, 2001 2:01 PM To: Multiple recipients of = list=20
 ORACLE-L Subject: RE: Date comparison = question </DIV>
 > -----Original Message----- >=20
 From: Lisa Yates [<A=20
 =
href=3D"mailto:cosnit_at_creighton.edu">mailto:cosnit_at_creighton.edu</A>]</FO= NT>=20
 > Sent: lundi, 8. janvier 2001 11:27 = <FONT=20
 size=3D2>> > Why doesn't this query = ever=20
 return... > > where=20
 run_date =3D to_date('01-03-2001 16:34:59','mm-dd-yyyy =

</FONT><BR><FONT=20
  size=3D2>&gt; hh24:mi:ss')</FONT> <BR><FONT size=3D2>&gt; =
</FONT><BR><FONT=20
  size=3D2>&gt; but this query does....</FONT> <BR><FONT size=3D2>&gt;=20

> where to_char(run_date) =3D=20 to_char(to_date('01-03-2001 > = 16:34:59','mm-dd-yyyy=20
 hh24:mi:ss')) > > and so=20
 does this query.... > >=20
 where to_char(run_date,'mm-dd-yyyy hh24:mi:ss') =3D '01-03-2001 = <FONT=20
 size=3D2>> 16:34:59' 
 Well, I guess my suggestion that run_date may = contain a "BCE"=20
 (before common era) date was not the answer to your problem. Maybe I=20 misunderstood the issue. When you say "why doesn't the query ever = return", do=20
 you mean it returns zero rows, or do you mean that the query is taking = an=20
 abnormally long time? If it's taking an abnormally long time, an = explain plan=20
 on the two queries may reveal the cause. Jacques R. Kilcho=EBr (949)=20
 754-8816 Quest Software, Inc. 8001 Irvine Center Drive Irvine,=20
 California 92618 U.S.A. <A=20
 href=3D"http://www.quest.com" = Received on Mon Jan 08 2001 - 16:44:59 CST