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1d352325b8
The code for raising a NUMERIC value to an integer power wasn't very careful about large powers. It got an outright wrong answer for an exponent of INT_MIN, due to failure to consider overflow of the Abs(exp) operation; which is fixable by using an unsigned rather than signed exponent value after that point. Also, even though the number of iterations of the power-computation loop is pretty limited, it's easy for the repeated squarings to result in ridiculously enormous intermediate values, which can take unreasonable amounts of time/memory to process, or even overflow the internal "weight" field and so produce a wrong answer. We can forestall misbehaviors of that sort by bailing out as soon as the weight value exceeds what will fit in int16, since then the final answer must overflow (if exp > 0) or underflow (if exp < 0) the packed numeric format. Per off-list report from Pavel Stehule. Back-patch to all supported branches. |
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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/.