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14bdb023cc
are all in new-in-8.2 logic associated with indexability of ScalarArrayOpExpr (IN-clauses) or amortization of indexscan costs across repeated indexscans on the inside of a nestloop. In particular: Fix some logic errors in the estimation for multiple scans induced by a ScalarArrayOpExpr indexqual. Include a small cost component in bitmap index scans to reflect the costs of manipulating the bitmap itself; this is mainly to prevent a bitmap scan from appearing to have the same cost as a plain indexscan for fetching a single tuple. Also add a per-index-scan-startup CPU cost component; while prior releases were clearly too pessimistic about the cost of repeated indexscans, the original 8.2 coding allowed the cost of an indexscan to effectively go to zero if repeated often enough, which is overly optimistic. Pay some attention to index correlation when estimating costs for a nestloop inner indexscan: this is significant when the plan fetches multiple heap tuples per iteration, since high correlation means those tuples are probably on the same or adjacent heap pages. |
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| contrib | ||
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| aclocal.m4 | ||
| configure | ||
| configure.in | ||
| COPYRIGHT | ||
| GNUmakefile.in | ||
| Makefile | ||
| README | ||
| README.CVS | ||
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 including some of the more common listed below: C++ - http://thaiopensource.org/development/libpqxx/ JDBC - http://jdbc.postgresql.org ODBC - http://odbc.postgresql.org Perl - http://search.cpan.org/~dbdpg/ PHP - http://www.php.net Python - http://www.initd.org/ Ruby - http://ruby.scripting.ca/postgres/ Other language binding are available from a variety of contributing parties. PostgreSQL also has a great number of procedural languages available, a short but not complete list is below: PL/pgSQL - included in PostgreSQL source distribution PL/Perl - included in PostgreSQL source distribution PL/PHP - http://projects.commandprompt.com/projects/public/plphp PL/Python - included in PostgreSQL source distribution PL/Java - http://gborg.postgresql.org/project/pljava/projdisplay.php PL/Tcl - included in PostgreSQL source distribution 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. Changes between all PostgreSQL releases are recorded in the file HISTORY. 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/.