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Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <21BC916B-80A1-43BF-8650-3363CCDAE09C@postgrespro.ru> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On 5/1/18 12:27, Stas Kelvich wrote: > Clock-SI is described in [5] and here I provide a small overview, which > supposedly should be enough to catch the idea. Assume that each node runs Commit > Sequence Number (CSN) based visibility: database tracks one counter for each > transaction start (xid) and another counter for each transaction commit (csn). > In such setting, a snapshot is just a single number -- a copy of current CSN at > the moment when the snapshot was taken. Visibility rules are boiled down to > checking whether current tuple's CSN is less than our snapshot's csn. Also it > worth of mentioning that for the last 5 years there is an active proposal to > switch Postgres to CSN-based visibility [6]. But that proposal has so far not succeeded. How are you overcoming the reasons for that? -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services