mirror of
https://github.com/postgres/postgres.git
synced 2025-04-29 13:56:47 +03:00
db76b1efbb
Previously we only allowed SetHintBits() to succeed if the commit LSN of the last transaction touching the page has already been flushed to disk. We can't generally change the LSN of the page, because we don't necessarily have the required locks on the page. But the required LSN interlock does not mean the commit record has to be flushed immediately, it just requires that the commit record will be flushed before the page is written out. Therefore if the buffer LSN is newer than the commit LSN, the hint bit can be safely set. In a number of scenarios (e.g. pgbench) this noticeably increases the number of hint bits are set. But more importantly it also keeps the success rate up when flushing WAL less frequently. That was the original reason for commit 4de82f7d7, which has negative performance consequences in a number of scenarios. This will allow a followup commit to reduce the flush rate. Discussion: 20160118163908.GW10941@awork2.anarazel.de
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: http://www.postgresql.org/download See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.