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 1rh6ob-009e8v-2p for pgsql-hackers@arkaria.postgresql.org; Mon, 04 Mar 2024 11:49:05 +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 1rh6oZ-00762h-JQ for pgsql-hackers@arkaria.postgresql.org; Mon, 04 Mar 2024 11:49:04 +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 1rh6oZ-00762X-A9 for pgsql-hackers@lists.postgresql.org; Mon, 04 Mar 2024 11:49:03 +0000 Received: from m16.mail.163.com ([117.135.210.5]) by magus.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1rh6oU-002iCw-Gt for pgsql-hackers@lists.postgresql.org; Mon, 04 Mar 2024 11:49:03 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-ID:MIME-Version: Content-Type; bh=LoTBf8/sAlV79ZWEI98KvlWEXhh6+l10TAFVs4BrC04=; b=cuEs3wWKOftVvDGxomd/X+M1owr/HQJ8z+f6Eh/BOSd2+qTqNzs+PLTtgHkHA3 7S4b2ok93o311HBMmXyWSL3Q3rCkQUqiLvFOWv6Ty8xQqghB0msS3zvK56TuqtVg Pv3no90bYPBeDRwnzpeYfoWJEiRS4Ea5q/yK5YmyBsyrU= Received: from 8235eee8a2a0 (unknown [140.205.118.119]) by gzga-smtp-mta-g1-1 (Coremail) with SMTP id _____wCXrwsateVlGJUsAQ--.27588S3; Mon, 04 Mar 2024 19:48:42 +0800 (CST) References: User-agent: mu4e 1.10.7; emacs 29.1 From: Andy Fan To: Richard Guo Cc: PostgreSQL-development , pgsql-hackers@lists.postgresql.org Subject: Re: Eager aggregation, take 3 Date: Mon, 04 Mar 2024 19:45:43 +0800 In-reply-to: Message-ID: <87il22cj51.fsf@163.com> MIME-Version: 1.0 Content-Type: text/plain X-CM-TRANSID:_____wCXrwsateVlGJUsAQ--.27588S3 X-Coremail-Antispam: 1Uf129KBjvdXoWrXr45Ar1rGFykCry7ZFWfGrg_yoWxWwc_ur yUtrWv9an0y3yfA3W0vwnxXF1fWay8Wr17J34rXr1xKayUJFZ3Ca1kKFyUJr4rtws3ur9x GrnIvw109r4IqjkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7xRqedU5UUUUU== X-Originating-IP: [140.205.118.119] X-CM-SenderInfo: x2klx3xlid0iqsrtqiywtou0bp/1tbiQBmXU2VOBuyG5wACs- List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk Richard Guo writes: > Hi All, > > Eager aggregation is a query optimization technique that partially > pushes a group-by past a join, and finalizes it once all the relations > are joined. Eager aggregation reduces the number of input rows to the > join and thus may result in a better overall plan. This technique is > thoroughly described in the 'Eager Aggregation and Lazy Aggregation' > paper [1]. This is a really helpful and not easy task, even I am not sure when I can spend time to study this, I want to say "Thanks for working on this!" first and hope we can really progress on this topic. Good luck! -- Best Regards Andy Fan