Обсуждение: Multikey Index GISt

<div class="Section1"><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">I need to implement a new GisT index that use multikey (i.e. tree columns).</span></font><p
class="MsoNormal"><fontface="Arial" size="2"><span style="font-size:10.0pt; 
font-family:Arial">I need to storage in the entry index the three transformed columns alltogether.</span></font><p
class="MsoNormal"><fontface="Arial" size="2"><span style="font-size:10.0pt; 
font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">If a use “create index anIndex on tablename using ( atr1   atr1_ops,  atr2  atr2_ops,  atr3  
atr3_ops)“, </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; 
font-family:Arial">I will obtain three separated invocation of “compress” function (one for each XXX_ops). I need to
receivethem in only one invocation. How can I do it using GIsT?</span></font><p class="MsoNormal"><font face="Arial"
size="2"><spanstyle="font-size:10.0pt; 
font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">I am using PostgreSQL8.2.3. How does it work the multikey GIsT announced in the latest version of
PosgreSQL?</span></font><pclass="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt; 
font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Thanks a lot,</span></font><p class="MsoNormal"><font face="Arial" size="2"><span
style="font-size:10.0pt;
font-family:Arial">Leticia</span></font></div>

"Leticia" <lgomez@itba.edu.ar> writes:
> If a use "create index anIndex on tablename using ( atr1   atr1_ops,  atr2
> atr2_ops,  atr3   atr3_ops) ", 

> I will obtain three separated invocation of "compress" function (one for
> each XXX_ops). I need to receive them in only one invocation.

You can't.  The fact that you want to means that you don't actually have
three independent operator classes there.  Perhaps what you really need
is a functional index on some function of the three columns?
        regards, tom lane