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/.
Robert Haas
authored
This commit extends the SortSupport infrastructure to allow operator classes the option to provide abbreviated representations of Datums; in the case of text, we abbreviate by taking the first few characters of the strxfrm() blob. If the abbreviated comparison is insufficent to resolve the comparison, we fall back on the normal comparator. This can be much faster than the old way of doing sorting if the first few bytes of the string are usually sufficient to resolve the comparison. There is the potential for a performance regression if all of the strings to be sorted are identical for the first 8+ characters and differ only in later positions; therefore, the SortSupport machinery now provides an infrastructure to abort the use of abbreviation if it appears that abbreviation is producing comparatively few distinct keys. HyperLogLog, a streaming cardinality estimator, is included in this commit and used to make that determination for text. Peter Geoghegan, reviewed by me.
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| COPYRIGHT | ||
| GNUmakefile.in | ||
| HISTORY | ||
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| README | ||
| README.git | ||
| aclocal.m4 | ||
| configure | ||
| configure.in |