请教高手关于query_plan的问题
<p>有没有高手知道：</p><p>IQ生成的query_plan中， <strong><font size="2">Condition 1 Usefulness 和 Condition 1 Selectivity</font></strong></p><p><strong><font size="2">是什么意思。</font></strong></p><p><strong><font size="2">另外我有一个SQL</font></strong></p><p>select * from a where <br/>date > '2006-02-02' and date < '2007-02-02' and <br/>org = '110999' （在date上有一个LF索引）</p><p>我单独执行</p><p>select * from a where <br/>date > '2006-02-02' and date < '2007-02-02' </p><p>比执行</p><p>select * from a where <br/>date > '2006-02-02' and date < '2007-02-02' and <br/>org = '110999'</p><p>要快，是怎么回事？</p>
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