operator class

<div class="Section1"><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Hello </span></font><p class="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">I have just started with postgreSQL. </span></font><p class="MsoNormal"><font face="Arial"
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font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">I have a file with the following commands :</span></font><p class="MsoNormal"><font face="Arial"
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font-family:"Courier New"">CREATE TYPE t_cod_t_activ AS (</span></font><p class="MsoNormal"><font face="Courier New"
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font-family:"Courier New"">      cod_t_activ       CHAR(10)</span></font><p class="MsoNormal"><font face="Courier New"
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font-family:"Courier New"">      );</span></font><p class="MsoNormal"><font face="Times New Roman" size="3"><span
style="font-size:
12.0pt"> </span></font><p class="MsoNormal"><font face="Courier New" size="2"><span style="font-size:10.0pt;
font-family:"Courier New"">CREATE TABLE tip_activ (</span></font><p class="MsoNormal"><font face="Courier New"
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font-family:"Courier New"">      id_tip_activ            t_cod_t_activ,</span></font><p class="MsoNormal"><font
face="CourierNew" size="2"><span style="font-size:10.0pt; 
font-family:"Courier New"">      des_t_activ             t_des_t_activ</span></font><p class="MsoNormal"><font
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font-family:"Courier New"">      );</span></font><p class="MsoNormal"><font face="Courier New" size="2"><span
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font-family:"Courier New""> </span></font><p class="MsoNormal"><font face="Courier New" size="2"><span
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font-family:"Courier New"">CREATE INDEX i_tip_activ ON tip_activ (id_tip_activ bpchar_pattern_ops);</span></font><p
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font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">When the CREATE INDEX is executed, this error shows:</span></font><p class="MsoNormal"><font
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12.0pt">ERROR:  operator class "bpchar_pattern_ops" does not accept data type t_cod_t_activ</span></font><p
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font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Does it mean that I cannot create an index on a field wich is of a type defined by the
user?</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">I need that id_tip_activ be PRIMARY KEY.</span></font><p class="MsoNormal"><font face="Arial"
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font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Thanks and best regards</span></font><p class="MsoNormal"><font face="Arial" size="2"><span
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font-family:Arial"> </span></font><p class="MsoNormal"><font face="Arial" size="2"><span style="font-size:10.0pt;
font-family:Arial">Miguel Ibáñez</span></font><p class="MsoNormal"><font face="Arial" size="2"><span
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font-family:Arial"> </span></font></div>