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[99.10.92.30]) by smtp.gmail.com with ESMTPSA id 94sm7351560otg.70.2019.11.19.05.49.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Nov 2019 05:49:25 -0800 (PST) From: Andrew Dunstan X-Google-Original-From: Andrew Dunstan Subject: Re: backup manifests To: Rushabh Lathia , Robert Haas , PostgreSQL Hackers Cc: Jeevan Chalke , vignesh C , David Steele References: <4b6244ea-4094-9055-080b-7afb274bf270@pgmasters.net> <146910fc-3df7-eeb4-ac5b-2f57a01f646f@pgmasters.net> Openpgp: preference=signencrypt Autocrypt: addr=andrew.dunstan@2ndQuadrant.com; prefer-encrypt=mutual; keydata= xsBNBE7KWFkBCAClridxur2AIc7eW2AR7izbfp3EnNefie2HbLF0izW5Ik5UjX2HBXBx4syI gY6b0ugohXrr274+baoAlvSbq6cAoQuEVrk5IZFzt20b1Xkx65FwGSEj526yiKLocqkJceSq Xr9xcA5SGY+FZv441chh5SU92v4q6z+6LPpoHOh97ptAVXZYNTtU0LevyvD5lja0TzbvJm6C eFXitJfnm1pLEr0DGJCR/iUOl/N62Kh4855zZC7NHIjQHPOvV5Stz/l5ilDhvGVk+xkXFPys SjZoUr1rXhYLpiyi5sR0X9FHXT0KnGuz1F5ERO7ZTLSSQ6fJwPj6gOk9K+vvoKvoeql5ABEB AAHNL0FuZHJldyBEdW5zdGFuIDxhbmRyZXcuZHVuc3RhbkAybmRRdWFkcmFudC5jb20+wsCY BBMBAgBCAhsDBgsJCAcDAgYVCAIJCgsEFgIDAQIeAQIXgAUJDyV6hBYhBOQ+WEYd/Hy/RGkV pZn6f8tZ/DuBBQJcH/EVAhkBAAoJEJn6f8tZ/DuB7BEH/iDWZEbVft2m2MT6SPjARzTupt/l xLLZ/Cl6n2US2hov5+fBbnR5xvECk/YCOfG9ICvKNlpFjceqNLRKStd8cmndnI+kDw91uNM2 hpL4aJMeW65XCHvqXlOLSwv5chBpXz9NG7FMaJ+q+59sWEWjcTNmjXgkEHn53y+1pc7nSLDe cr5ZI1aB3nGXRm1SoDY5PYZkUKMykW+YBZwgcs/Q5tRaE+siN7DKbz8E628+PerwAkmHPVXN MdJFD6gs4S0gDFA8IxcyIwZU2v4By+brzcJ9Se3FK5BYxBDHtaYZxgSrJAvOUOrLIZPQTQfL TtnVs3C3JTfrxCH1ceHtnA6dRuTOwE0ETspYWQEIANGc4zQULOxhbqO2dyD51YhqCNRmm9oK Waqf+wmW4tpDe/VVcxAnNizd4LWCHfzpb5cHAtGkOPePMfzWVf6nvdF7d3eglbtf59+zG7O7 llV0xSSoFiieQBsrGvqDInXYX/4mRRXMtyhM353/tixC9RWLs1oofyYmCPPXXY7h9R7en3B8 BoVrRFcdzlIY/NFNhFGW/9dkEiGjgna2Rk6e15kln4ZvFBWUg23p93w/pqXcxY6+k/8TEk+C 4R+M6w7o2PLGOjdZ+kPiUcw5H85zf/yZJwQXzisXaNduwWB6Vads9YC9dj6kPR1c4VGRqAaY L++LAEOqrlvm2TvqQqZRtnEAEQEAAcLAZQQYAQIADwIbDAUCXA6fpAUJDyV6xAAKCRCZ+n/L Wfw7geU4B/9vFFsVmWxerDWgNjyiK80zIPmlw/iwdUlU6FIu0JWLMg4093kvxBs7RMZV9hBq n3ekBvD4IvFsVLJrw9qzSI2FH3UeYy5WXpEs01Ppia60NOlvRDqXbryzuvfe+iYo6bVP3Ikr TPTNYL/BePUTD2DPvSI82SbGTyzuA7SJv6NRqqQDMIy1fU6KyQFLmQJp/QJyhKWzm9jWh8ee w8jVaoMY0Kbq5N7RqisEx1Lu/Iw646UphdYzQNymf+kbiU5Kf4I6DhzV8w9sie1Bo1juNj3I c5/fFJsmxljbnaDbXPcnFsur1Oo9mIHFakgWgOBMuxoWfjONiLjjLh/9+ZIqSSLX Message-ID: Date: Tue, 19 Nov 2019 08:49:24 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-MW List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On 11/19/19 5:00 AM, Rushabh Lathia wrote: > > > My colleague Suraj did testing and noticed the performance impact > with the checksums.   On further testing, he found that specifically with > sha its more of performance impact.   > > I admit I haven't been following along closely, but why do we need a cryptographic checksum here instead of, say, a CRC? Do we think that somehow the checksum might be forged? Use of cryptographic hashes as general purpose checksums has become far too common IMNSHO. cheers andrew -- Andrew Dunstan https://www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services