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. 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/.
Tom Lane
authored
Not only is this implementation of secondary-split not better than the default implementation in gistsplit.c, it's actually worse. The gistsplit.c code at least looks to see if switching the left and right sides would make a better merge with the previously-split tuples, while this doesn't. In any case it's rather useless to support secondary split only in an edge case. There used to be more complete support for it here (in chooseLR()), but that was removed in commit 7f3bd868. It appears to me though that the chooseLR() code was really isomorphic to the default implementation, since it was still based on choosing the cheaper way of adding two sub-split vectors that had been chosen without regard to the primary split initially. I think an implementation of secondary split that could beat the default implementation would have to be pretty fully integrated into the split algorithm, not plastered on at the end. Back-patch to 9.2, but not further; previous branches have the chooseLR() code which I don't feel a great need to mess with. This is mainly so we just have two behaviors and not three among the various branches (IOW, this patch is cleanup for commit 7f3bd868's incomplete removal of secondary-split support).
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| README | ||
| README.git | ||
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| configure.in |