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Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: luhuayi <luhuayi@huawei.com> Co-committed-by: luhuayi <luhuayi@huawei.com>
25 lines
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25 lines
4.1 KiB
HTML
<a name="EN-US_TOPIC_0000002125650482"></a><a name="EN-US_TOPIC_0000002125650482"></a>
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<h1 class="topictitle1">GaussDB(DWS) Foreign Table Function Development Specifications</h1>
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<div id="body8662426"><div class="section" id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_section7984144034412"><h4 class="sectiontitle">Rule 4.1 Deploying GDS on an Independent Server Outside the GaussDB(DWS) Cluster</h4><div class="note" id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_note1893311844614"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p1418881295812"><strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b1963863015016">Impact of rule violation:</strong></p>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p0738165017216">If GDS is deployed in a GaussDB(DWS) cluster, it contends for resources with CNs or DNs in the cluster, which leads to a decline in the performance of both GDS and CNs or DNs.</p>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p10188141245817"><strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b7519124332017">Solution:</strong></p>
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<ul id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_ul1173125635215"><li id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_li77841258105210">Deploy GDS on an independent server outside the GaussDB(DWS) cluster.</li><li id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_li138341507506">Ensure that the disk capacity of the GDS server and the network bandwidth between the GDS server and the GaussDB(DWS) cluster are planned according to the requirements.</li></ul>
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</div></div>
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</div>
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<div class="section" id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_section171861828194514"><h4 class="sectiontitle">Rule 4.2 Avoiding Concurrent Access to Multiple Collaborative Analysis Foreign Tables Across Clusters</h4><div class="note" id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_note319293211509"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p4608437155020"><strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b199031941205312">Principle description</strong>: When cluster A accesses data in cluster B through collaborative analysis, all DNs in cluster A establish connections and active sessions with the CNs in cluster B.</p>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p181920321503"><strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b106133351773">Impact of rule violation:</strong></p>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p81642546215">The CNs in cluster B are overloaded. As a result, the number of connections and active sessions exceeds the threshold, and the access is abnormal.</p>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p219293265013"><strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b319253245017">Solution:</strong></p>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p768125532113">Use foreign tables to access a single table instead of performing concurrent queries on multiple foreign tables. If it is not possible to avoid concurrent queries, calculate and limit the number of concurrent queries based on the number of DNs in cluster A and the normal service volume of cluster B. Additionally, increasing the values of <strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b297124619276">max_active_statements</strong> and <strong id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_b1350118582271">max_connections</strong> can help solve the problem.</p>
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</div></div>
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<p id="EN-US_TOPIC_0000002125650482__en-us_topic_0000002160959045_p41831541101620"></p>
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</div>
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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_04_0074.html">GaussDB(DWS) Development Design Proposal</a></div>
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</div>
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</div>
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