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The planner can sometimes compute very large values for numGroups, and in cases where we have no alternative to building a hashtable, such a value will get fed directly to BuildTupleHashTable as its nbuckets parameter. There were two ways in which that could go bad. First, BuildTupleHashTable declared the parameter as "int" but most callers were passing "long"s, so on 64-bit machines undetected overflow could occur leading to a bogus negative value. The obvious fix for that is to change the parameter to "long", which is what I've done in HEAD. In the back branches that seems a bit risky, though, since third-party code might be calling this function. So for them, just put in a kluge to treat negative inputs as INT_MAX. Second, hash_create can go nuts with extremely large requested table sizes (notably, my_log2 becomes an infinite loop for inputs larger than LONG_MAX/2). What seems most appropriate to avoid that is to bound the initial table size request to work_mem. This fixes bug #6035 reported by Daniel Schreiber. Although the reported case only occurs back to 8.4 since it involves WITH RECURSIVE, I think it's a good idea to install the defenses in all supported branches.
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/.