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Lu, Huayi ef0ada5a59 DWS DEV 20240716 version 
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>
2024-11-02 09:07:47 +00:00

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<a name="EN-US_TOPIC_0000001460721168"></a><a name="EN-US_TOPIC_0000001460721168"></a>
<h1 class="topictitle1">Configuration Settings Functions</h1>
<div id="body8662426"><p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_a4b0663665bdc490fb89c9fc38be999ae">Configuration setting functions are used for querying and modifying configuration parameters during running.</p>
<div class="section" id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_section1352018015210"><h4 class="sectiontitle">current_setting(setting_name)</h4><p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_p978716125319">Description: Specifies the current setting.</p>
<p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_p178717121330">Return type: text</p>
<p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_p157877128316">Note: <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_b175441214125810">current_setting</strong> obtains the current setting of <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_b1545114135812">setting_name</strong> by query. It is equivalent to the <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_b84235270617917">SHOW</strong> statement. For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_screen27871612432"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">current_setting</span><span class="p">(</span><span class="s1">'datestyle'</span><span class="p">);</span>
<span class="w"> </span><span class="n">current_setting</span>
<span class="c1">-----------------</span>
<span class="w"> </span><span class="n">ISO</span><span class="p">,</span><span class="w"> </span><span class="n">MDY</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="section" id="EN-US_TOPIC_0000001460721168__section102551916663"><h4 class="sectiontitle">read_global_var(global_setting_name)</h4><p id="EN-US_TOPIC_0000001460721168__p11255141613617">Description: Reads the current value of a global variable.</p>
<p id="EN-US_TOPIC_0000001460721168__p132559165620">Return type: text</p>
<p id="EN-US_TOPIC_0000001460721168__p825518161661">Note: <strong id="EN-US_TOPIC_0000001460721168__b1369993813294">read_global_var</strong> is used query the current value of <strong id="EN-US_TOPIC_0000001460721168__b397412223014">global_setting_name</strong>. It is equivalent to the <strong id="EN-US_TOPIC_0000001460721168__b1854992478">SHOW</strong> statement.</p>
<p id="EN-US_TOPIC_0000001460721168__p20730390282">Example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001460721168__screen12255816567"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SET</span><span class="w"> </span><span class="n">my</span><span class="p">.</span><span class="n">var</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="mi">1000</span><span class="p">;</span>
<span class="k">SELECT</span><span class="w"> </span><span class="n">read_global_var</span><span class="p">(</span><span class="s1">'my.var'</span><span class="p">);</span>
<span class="w"> </span><span class="n">read_global_var</span>
<span class="c1">-----------------</span>
<span class="w"> </span><span class="mi">1000</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
</div>
<div class="note" id="EN-US_TOPIC_0000001460721168__note19240125681013"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000001460721168__p22401856191016"><strong id="EN-US_TOPIC_0000001460721168__b5446431163011">global_setting_name</strong> indicates a variable similar to <strong id="EN-US_TOPIC_0000001460721168__b1551038173019">my.var</strong>. The variable name contains decimal points and the left and right sides of the decimal points are not empty. Variables of this type are called global variables.</p>
<p id="EN-US_TOPIC_0000001460721168__p431515351138">Global variables can be set only by running the <strong id="EN-US_TOPIC_0000001460721168__b231491113417">SET</strong> command. Methods such as <strong id="EN-US_TOPIC_0000001460721168__b129413183349">gs_guc</strong>, <strong id="EN-US_TOPIC_0000001460721168__b993143011343">ALTER DATABASE dbname SET paraname TO value</strong>, and <strong id="EN-US_TOPIC_0000001460721168__b144230388343">ALTER USER username SET paraname TO value</strong> are not supported. Global variables are visible to all users.</p>
</div></div>
<div class="section" id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_section153618515220"><h4 class="sectiontitle">set_config(setting_name, new_value, is_local)</h4><p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_p928815101522">Description: Sets the parameter and returns a new value.</p>
<p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_p142887101528">Return type: text</p>
<p id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_p8288610725">Note: <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b842352706173541">set_config</strong> sets the parameter <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b842352706173549">setting_name</strong> to <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b842352706173558">new_value</strong>. If <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b84235270617367">is_local</strong> is <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b842352706173614">true</strong>, the new value will only apply to the current transaction. If you want the new value to apply for the current session, use <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b84235270617378">false</strong> instead. The function corresponds to the <strong id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_en-us_topic_0058965547_b842352706173713">SET</strong> statement. For example:</p>
<div class="codecoloring" codetype="Sql" id="EN-US_TOPIC_0000001460721168__en-us_topic_0000001188110548_screen1288010523"><div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span class="normal">1</span>
<span class="normal">2</span>
<span class="normal">3</span>
<span class="normal">4</span>
<span class="normal">5</span>
<span class="normal">6</span></pre></div></td><td class="code"><div><pre><span></span><span class="k">SELECT</span><span class="w"> </span><span class="n">set_config</span><span class="p">(</span><span class="s1">'log_statement_stats'</span><span class="p">,</span><span class="w"> </span><span class="s1">'off'</span><span class="p">,</span><span class="w"> </span><span class="k">false</span><span class="p">);</span>
<span class="w"> </span><span class="n">set_config</span>
<span class="c1">------------</span>
<span class="w"> </span><span class="k">off</span>
<span class="p">(</span><span class="mi">1</span><span class="w"> </span><span class="k">row</span><span class="p">)</span>
</pre></div></td></tr></table></div>
</div>
<div class="caution" id="EN-US_TOPIC_0000001460721168__note178311515266"><span class="cautiontitle"><img src="public_sys-resources/caution_3.0-en-us.png"> </span><div class="cautionbody"><p id="EN-US_TOPIC_0000001460721168__p883111162618">If <strong id="EN-US_TOPIC_0000001460721168__b72128541343">behavior_compat_options</strong> is set to <strong id="EN-US_TOPIC_0000001460721168__b2989757133410">DISABLE_SET_GLOBAL_VAR_ON_DATANODE</strong>, you cannot use this function to set global variables on DNs.</p>
</div></div>
</div>
</div>
<div>
<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_06_0052.html">System Administration Functions</a></div>
</div>
</div>
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