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| 18 | <html> |
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| 19 | <head> |
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| 20 | <title>Min Number Should Match Specification Format</title> |
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| 21 | </head> |
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| 22 | |
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| 23 | <body> |
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| 24 | <h1>Min Number Should Match Specification Format</h1> |
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| 25 | |
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| 26 | <blockquote> |
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| 27 | This document explains the format used for specifying the |
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| 28 | "Min Number Should Match" criteria of the BooleanQuery objects built by the |
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| 29 | DisMaxRequestHandler. |
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| 30 | </blockquote> |
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| 31 | |
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| 32 | |
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| 33 | <h2>Explaination of Concept: "Min Number Should Match"</h2> |
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| 34 | <div> |
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| 35 | :TODO: |
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| 36 | </div> |
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| 37 | |
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| 38 | |
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| 39 | <h2>Specification Format</h2> |
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| 40 | <div> |
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| 41 | |
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| 42 | <p>Specification strings may have the following formats...</p> |
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| 43 | |
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| 44 | <dl> |
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| 45 | |
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| 46 | <dt><code>3</code></dt> |
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| 47 | <dd>A positive integer, indicating a fixed value regardless of the |
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| 48 | number of optional clauses. |
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| 49 | </dd> |
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| 50 | |
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| 51 | <dt><code>-2</code></dt> |
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| 52 | <dd>A negative integer, indicating that the total number of optional clauses, |
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| 53 | minus this number should be mandatory. |
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| 54 | </dd> |
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| 55 | |
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| 56 | <dt><code>75%</code></dt> |
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| 57 | <dd>A percentage, indicating that this percent of the total number of |
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| 58 | optional clauses are neccessary. The number computed from the |
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| 59 | percentage is rounded down and used as the minimum. |
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| 60 | </dd> |
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| 61 | |
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| 62 | <dt><code>-25%</code></dt> |
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| 63 | <dd>A negative percentage, indicating that this percent of the total |
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| 64 | number of optional clauses can be missing. The number computed from the |
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| 65 | percentage is rounded down, before being subtracted from the total |
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| 66 | to determine the minimum. |
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| 67 | </dd> |
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| 68 | |
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| 69 | <dt><code>3<90%</code></dt> |
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| 70 | <dd>A positive integer, followed by the less-than symbol, followed |
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| 71 | by any of the previously mentioned specifiers is a conditional |
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| 72 | specification. It indicates that if the number of optional clauses is |
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| 73 | equal to (or less than) the integer, they are all required, but |
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| 74 | if it's greater then the integer, the specification applies. |
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| 75 | In this example: if there are 1 to 3 clauses they are all required, |
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| 76 | but for 4 or more clauses only 90% are required. |
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| 77 | </dd> |
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| 78 | |
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| 79 | <dt><code>2<-25% 9<-3</code></dt> |
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| 80 | <dd>Multiple conditional specifications can be seperated by spaces, |
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| 81 | each one only being valid for numbers greater then the one before it. |
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| 82 | In this example: if there are 1 or 2 clauses both are required, |
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| 83 | if there are 3-9 clauses all but 25% are requred, and if there |
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| 84 | are more then 9 clauses, all but three are required. |
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| 85 | </dd> |
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| 86 | </dl> |
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| 87 | |
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| 88 | <p> |
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| 89 | A few important notes... |
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| 90 | </p> |
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| 91 | |
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| 92 | <ul> |
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| 93 | <li> |
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| 94 | When dealing with percentages, negative values can be used to get |
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| 95 | different behavior in edge cases. 75% and -25% mean the same thing |
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| 96 | when dealing with 4 clauses, but when dealing with 5 clauses 75% means |
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| 97 | 3 are required, but -25% means 4 are required. |
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| 98 | </li> |
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| 99 | <li> |
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| 100 | If the calculations based on the specification determine that no |
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| 101 | optional clauses are needed, the usual rules about BooleanQueries |
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| 102 | still apply at search time (a BooleanQuery containing no required |
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| 103 | clauses must still match at least one optional clause) |
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| 104 | </li> |
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| 105 | <li> |
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| 106 | No matter what number the calculation arrives at, |
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| 107 | a value greater then the number of optional clauses, or a value less then |
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| 108 | 1 will never be used. (ie: no matter how low or how high the result of the |
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| 109 | calculation result is, the minimum number of required matches will never |
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| 110 | be lower then 1 or greatered then the number of clauses. |
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| 111 | </li> |
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| 112 | </ul> |
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| 113 | |
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| 114 | |
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| 115 | </div> |
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| 116 | |
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| 117 | |
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| 118 | |
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| 119 | |
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| 120 | <hr> |
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| 121 | <pre> |
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| 122 | $Id: min-should-match.html 1144761 2011-07-09 23:01:53Z sarowe $ |
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| 123 | $Source:$ |
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| 124 | </pre> |
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| 125 | |
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| 126 | </body> </html> |
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