Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1szDVp-004sj9-I0 for pgsql-general@arkaria.postgresql.org; Fri, 11 Oct 2024 11:08:49 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1szDVn-001wc5-Ki for pgsql-general@arkaria.postgresql.org; Fri, 11 Oct 2024 11:08:47 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1szDVn-001wbw-8q for pgsql-general@lists.postgresql.org; Fri, 11 Oct 2024 11:08:47 +0000 Received: from mail-ej1-x632.google.com ([2a00:1450:4864:20::632]) by magus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1szDVg-000VLe-BK for pgsql-general@lists.postgresql.org; Fri, 11 Oct 2024 11:08:46 +0000 Received: by mail-ej1-x632.google.com with SMTP id a640c23a62f3a-a9951fba3b4so301064066b.1 for ; Fri, 11 Oct 2024 04:08:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1728644920; x=1729249720; darn=lists.postgresql.org; h=to:subject:message-id:date:from:mime-version:from:to:cc:subject :date:message-id:reply-to; bh=JnV9LK6fefqiN1jWJ466f6ngrPoNnSc9JHG4AN9MOME=; b=VjoqvQpHknnEROzH5ey0H2QNhSiGZ+tdXG6YELbH00LfwkVHbxdtMkCfcTbs3nKnjL IEMqfm4ZJDCqKfGOjL1MujGpmULEsFKSNi4u6G3f8CvT23ao/TYfcOVXlGklaxEJejH9 bhvKnRr7nWMhICMnBJco06keRDBJOl+JcUHqGpAdRpxT8AXX2w8qFq9f+eFmCA4ibThS KXIVwjBLeq1G7r8YDtexVr8xJnxFoogiZoE+aK0jUEzJpB3EgaSzNr1BxyFNpPduQjTC 6aO5CmuglDP7mnlnN64EyWj8VPHQMfEDvQRvI1hGc9sJ0LYjUaB3sKXvcEw1LchRdyRG XyKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728644920; x=1729249720; h=to:subject:message-id:date:from:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=JnV9LK6fefqiN1jWJ466f6ngrPoNnSc9JHG4AN9MOME=; b=Dkjg2VDruLytAzB/jNWHpvab8NxLLdGkdOHfz7tMQh/+DEQsWAvoTIE2p+/5C+kjan S8vMUXc7KxIgFdjULp2SQS8aiOjQw2CQVBNgDrnfsU1j+S4F0z/jy1C+jySCKtfNtRtt EzVcDqn3LflL7xU89ED2idVOQKe8q7ZtOvJG+vOZlOh98bVRTtVv0q+TqpfG9DgEwaCm AxB5DT/ZBknNb0SJ0DM2WgukDl+MJUoMzwQj22J1KHD9AJtqxgTWwrW5m0KQmt/c1Ms1 W52PDuIGWScQbRLugPCG5tq1ZagEMq1ZglNpboOgJ5Grqm+LpLI8G8TXQOFe1q0b/NOk j+Ew== X-Gm-Message-State: AOJu0YwvaFuInB0wJQDKVuT26X30fgj7K+YDp5ZNl3CYWb0IpXIhtmPa 8GVWV/xm46arWpg8Yy/LeoKG9ibrxy1ZXjJOBq8aJ49BsX+hgeVMPOxpNIwnyOFaifm1SZQFfyu SGxVWrO5T17yntLcOvbtK31DscybkWZFt X-Google-Smtp-Source: AGHT+IHntoxdMfTPtWr6KEx3aT9FltBZ1xNQ1WDtS56ObrnOH6zb1V5R7DSwvrfYGMAnEMrqyV6BQMH1HSbZDogzOjI= X-Received: by 2002:a17:907:e619:b0:a8d:5184:d94b with SMTP id a640c23a62f3a-a99b96ad1cbmr186193466b.49.1728644920071; Fri, 11 Oct 2024 04:08:40 -0700 (PDT) MIME-Version: 1.0 From: Koen De Groote Date: Fri, 11 Oct 2024 13:08:28 +0200 Message-ID: Subject: Foreign Data Wrapper behavior? To: PostgreSQL General Content-Type: multipart/alternative; boundary="000000000000675b6a06243182b9" List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk --000000000000675b6a06243182b9 Content-Type: text/plain; charset="UTF-8" In the release notes for postgres 17 I'm reading: > The PostgreSQL foreign data wrapper (postgres_fdw), used to execute queries on remote PostgreSQL instances, can now push EXISTS and IN subqueries to the remote server for more efficient processing. I'm confused as to what this means. In older versions, are parts of queries not sent to the foreign server? Or is this change meant to imply the sending of only the subqueries, the result of which is then directly used in pushing the entire query? Or am I still wrong as to what this means? I looked at the documentation and there doesn't seem to be any indication of particular queries not being pushed to the foreign server, so this wording that "can now push EXISTS and IN subqueries to the remote server" is confusing. What am I missing? Regards, Koen De Groote --000000000000675b6a06243182b9 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
In the release notes for postgres 17 I'm reading:=C2= =A0

> The PostgreSQL foreign data wrapper (postgres_fdw), = used to execute queries on remote PostgreSQL instances, can now push EXISTS= and IN subqueries to the remote server for more efficient processing.

I'm confused as to what this means. In older v= ersions, are parts of queries not sent to the foreign server? Or is this ch= ange meant to imply the sending of only the subqueries, the result of which= is then directly used in pushing the entire query?

=
Or am I still wrong as to what this means?

I looked at the documentation and there doesn't seem to be any indic= ation of particular queries not being pushed to the foreign server, so this= wording that "can now push EXISTS and IN subqueries to the remote ser= ver" is confusing.

What am I missing?

Regards,
Koen De Groote
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