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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Hi Giusseppe,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Thanks for your reply. As I was told before, there is now a ticket opened for this (<a href="https://trac.osgeo.org/postgis/ticket/4802">https://trac.osgeo.org/postgis/ticket/4802</a>)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">The query is executed as a parameterized query from a client, but also testing from pgAdmin with the parameters substituted for constants
(for instance, as 0,0) gives the same result:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">select * from my_table<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">where st_contains(geometry, st_setsrid(st_point(0, 0), find_srid('public', 'my_table', 'geometry')));<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US">I’ve run ANALYZE on the table but the plan didn’t change.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Paco Calvo<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">De:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> postgis-users <postgis-users-bounces@lists.osgeo.org>
<b>En nombre de </b>Giuseppe Broccolo<br>
<b>Enviado el:</b> martes, 24 de noviembre de 2020 13:41<br>
<b>Para:</b> PostGIS Users Discussion <postgis-users@lists.osgeo.org><br>
<b>Asunto:</b> Re: [postgis-users] Spatial query not using the spatial index<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Paco,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">How is the query executed in the DB? Is it a prepared query, or are parameters (x, y) passed on the client side and then the resolved query is executed in the DB?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">In case of prepared query, the planner uses a "general" plan to execute the query: the plan is eventually corrected comparing the estimated costs in executing<o:p></o:p></p>
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<p class="MsoNormal">the query with the costs of the general plan, or used otherwise. The general plan is computed after the first 5 executions of the query, where execution plans are<o:p></o:p></p>
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<p class="MsoNormal">always estimated. From the 6th execution, the planner will try to use the general plan. Although the plan can be corrected basing on the passed parameters to<o:p></o:p></p>
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<p class="MsoNormal">the prepared statement, it can lead to odd behaviour since the correction is based on the costs, specially if the statistics related to the table are not properly<o:p></o:p></p>
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<p class="MsoNormal">updated.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">But please provide more details about how you execute the query.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Giuseppe.<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Il giorno mar 24 nov 2020 alle ore 10:23 Calvo Arias, Francisco <<a href="mailto:fcaa@tragsa.es">fcaa@tragsa.es</a>> ha scritto:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi all,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I’m having an issue with the planner using a sequential scan instead of the spatial index over a big table with several millions of geometries. My query is similar to this, where
the query parameters are the coordinates for a point:<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">select * from my table<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">where st_contains(geometry, st_setsrid(st_point(x, y), find_srid('public', 'my_table', 'geometry')))<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">This occurs with PostGIS 3.0 ('POSTGIS="3.0.3 3.0.3" [EXTENSION] PGSQL="110" GEOS="3.8.1-CAPI-1.13.3" PROJ="7.1.1" LIBXML="2.9.9" LIBJSON="0.12" LIBPROTOBUF="1.2.1" WAGYU="0.4.3
(Internal)"') on Potgres 11 and 9.6, both for Windows and fully patched. Works as expected on other instances with Postgres 10 and 12 and PostGIS 2.5.3 and 3.0.3, respectively.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Using other predicates as st_intersection instead of st_contains or reindexing and analyzing the table doesn’t work. Changing find_srid(…) for a constant value uses the expected
plan. As a workaround, I’ve extracted the construction of the second geometry (st_setsrid(…)) to a CTE, giving a plan similar to the expected one.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I’m thinking of a different configuration of the plannner in those instances with the problem, but I’m not really sure.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Any help is welcome.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks in advance,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Paco Calvo<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
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