title: low performance by DBINFO('sqlca.sqlerrd1') of Informix 9.40
body: <p>After a row was inserted I read the serial of inserted row with  DBINFO('sqlca.sqlerrd1'). The select proccess takes a lot of time ( 5 - 10 sec ).
  For the analyse I switch on the sqexplain before the insert command</p>
  
  <pre><code>set explain on;
  load from x  insert into  transaction;
  SELECT distinct dbinfo('sqlca.sqlerrd1') FROM transaction;
  </code></pre>
  
  <p>The output :</p>
  
  <pre><code>QUERY:
          ------
          SELECT distinct dbinfo('sqlca.sqlerrd1') FROM transaction
  
          Estimated Cost: 353490
          Estimated # of Rows Returned: 10
  
            1) cms.transaction: SEQUENTIAL SCAN
  </code></pre>
  
  <p>I perform the update statistics:</p>
  
  <pre><code>update statistics medium for table transaction;
  </code></pre>
  
  <p>but this didn't help. Why the SQL-Engine perform the sequential scan?
  If I search with :</p>
  
  <pre><code>SELECT MAX (sernr ) from transaction;
  </code></pre>
  
  <p>(where sernr is serial field ) the SQL-Engine search with index.
  Here the output:</p>
  
  <pre><code>QUERY:
          ------
          SELECT MAX (sernr ) from transaction
  
          Estimated Cost: 4
          Estimated # of Rows Returned: 1
  
             1) cms.transaction: INDEX PATH
  
             (1) Index Keys: sernr   (Key-Only)  (Aggregate)  (Serial, fragments: ALL)
  </code></pre>
  
  <p>What I should to do for increase of performance? </p>