forked from docs/doc-exports
Lu, Huayi
e6fa411af0
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: Lu, Huayi <luhuayi@huawei.com> Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
62 lines
6.3 KiB
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62 lines
6.3 KiB
HTML
<a name="EN-US_TOPIC_0000001233708693"></a><a name="EN-US_TOPIC_0000001233708693"></a>
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<h1 class="topictitle1">Handling TSQuery</h1>
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<div id="body8662426"><p id="EN-US_TOPIC_0000001233708693__en-us_topic_0059778915_p69403371739"><span id="EN-US_TOPIC_0000001233708693__text1319044884">GaussDB(DWS)</span> provides functions and operators that can be used to manipulate queries that are already in tsquery type.</p>
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<ul id="EN-US_TOPIC_0000001233708693__u4c919f43d42f4beea2f3292184942ca6"><li id="EN-US_TOPIC_0000001233708693__leafaf5daeb814940aacff1885a68eefb">tsquery && tsquery<p id="EN-US_TOPIC_0000001233708693__a784ed11254ef4ee0aaff14ca760f025f"><a name="EN-US_TOPIC_0000001233708693__leafaf5daeb814940aacff1885a68eefb"></a><a name="leafaf5daeb814940aacff1885a68eefb"></a>Returns the AND-combination of the two given tsqueries.</p>
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</li></ul>
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<ul id="EN-US_TOPIC_0000001233708693__u0e25397606464519ab49f2de6c14a371"><li id="EN-US_TOPIC_0000001233708693__ld4c06a45aaa44316ae75ab1b376cfec0">tsquery || tsquery<p id="EN-US_TOPIC_0000001233708693__a20f0c2f8dc6f45a4b39d41a672c7a47a"><a name="EN-US_TOPIC_0000001233708693__ld4c06a45aaa44316ae75ab1b376cfec0"></a><a name="ld4c06a45aaa44316ae75ab1b376cfec0"></a>Returns the OR-combination of the two given tsqueries.</p>
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</li></ul>
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<ul id="EN-US_TOPIC_0000001233708693__u1e640263f88b43e1b5171886418de8d2"><li id="EN-US_TOPIC_0000001233708693__l50982ec8fef945178bcc9dd754d311ee">!! tsquery<p id="EN-US_TOPIC_0000001233708693__a534b1b18c36f4db1a6c7076002e25629"><a name="EN-US_TOPIC_0000001233708693__l50982ec8fef945178bcc9dd754d311ee"></a><a name="l50982ec8fef945178bcc9dd754d311ee"></a>Returns the negation (NOT) of the given tsquery.</p>
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</li></ul>
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<ul id="EN-US_TOPIC_0000001233708693__u00ebafb5ade14624bf90ab24cceabb7a"><li id="EN-US_TOPIC_0000001233708693__l19a82742d6c14f2794a4f18815aab33a">numnode(query tsquery) returns integer<p id="EN-US_TOPIC_0000001233708693__aa52ee5e95258445cad0a2f3ccb1cd40c"><a name="EN-US_TOPIC_0000001233708693__l19a82742d6c14f2794a4f18815aab33a"></a><a name="l19a82742d6c14f2794a4f18815aab33a"></a>Returns the number of nodes (lexemes plus operators) in a <strong id="EN-US_TOPIC_0000001233708693__b842352706161334">tsquery</strong>. This function is useful to determine if the query is meaningful (returns > 0), or contains only stop words (returns 0). For example:</p>
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<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001233708693__sbd4cbdd2901d4322812a5c7406f66dcf"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal"> 1</span>
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<span class="normal"> 2</span>
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<span class="normal"> 3</span>
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<span class="normal"> 4</span>
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<span class="normal"> 5</span>
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<span class="normal"> 6</span>
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<span class="normal"> 7</span>
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<span class="normal"> 8</span>
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<span class="normal"> 9</span>
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<span class="normal">10</span>
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<span class="normal">11</span>
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<span class="normal">12</span>
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<span class="normal">13</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">numnode</span><span class="p">(</span><span class="n">plainto_tsquery</span><span class="p">(</span><span class="s1">'the any'</span><span class="p">));</span>
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<span class="n">NOTICE</span><span class="p">:</span><span class="w"> </span><span class="nb">text</span><span class="o">-</span><span class="k">search</span><span class="w"> </span><span class="n">query</span><span class="w"> </span><span class="k">contains</span><span class="w"> </span><span class="k">only</span><span class="w"> </span><span class="n">stop</span><span class="w"> </span><span class="n">words</span><span class="w"> </span><span class="k">or</span><span class="w"> </span><span class="n">doesn</span><span class="s1">'t contain lexemes, ignored</span>
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<span class="s1">CONTEXT: referenced column: numnode</span>
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<span class="s1"> numnode </span>
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<span class="s1">---------</span>
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<span class="s1"> 0</span>
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<span class="s1">(1 row)</span>
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<span class="s1">SELECT numnode('</span><span class="n">foo</span><span class="w"> </span><span class="o">&</span><span class="w"> </span><span class="n">bar</span><span class="err">'</span><span class="p">::</span><span class="n">tsquery</span><span class="p">);</span>
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<span class="w"> </span><span class="n">numnode</span>
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<span class="c1">---------</span>
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<span class="w"> </span><span class="mi">3</span>
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<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
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</pre></div></td></tr></table></div>
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</div>
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</li></ul>
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<ul id="EN-US_TOPIC_0000001233708693__uc6c54b0a2b404fc8b85636f8ba1febe7"><li id="EN-US_TOPIC_0000001233708693__lff41ad967fd24bbaa1b54dc13ac2411a">querytree(query tsquery) returns text<p id="EN-US_TOPIC_0000001233708693__a18484ea3c94d46b9b1b6611ee1a50d4c"><a name="EN-US_TOPIC_0000001233708693__lff41ad967fd24bbaa1b54dc13ac2411a"></a><a name="lff41ad967fd24bbaa1b54dc13ac2411a"></a>Returns the portion of a <strong id="EN-US_TOPIC_0000001233708693__b842352706161356">tsquery</strong> that can be used for searching an index. This function is useful for detecting unindexable queries, for example those containing only stop words or only negated terms. For example:</p>
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<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001233708693__s4d17c3fb54164daa823cb25529caec27"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
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<span class="normal">2</span>
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<span class="normal">3</span>
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<span class="normal">4</span>
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<span class="normal">5</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">querytree</span><span class="p">(</span><span class="n">to_tsquery</span><span class="p">(</span><span class="s1">'!defined'</span><span class="p">));</span>
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<span class="w"> </span><span class="n">querytree</span><span class="w"> </span>
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<span class="c1">-----------</span>
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<span class="w"> </span><span class="n">T</span>
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<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
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</pre></div></td></tr></table></div>
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</div>
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</li></ul>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_06_0096.html">Additional Features</a></div>
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</div>
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</div>
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