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Many situations where the offset is infinity were not handled sanely. We should generally allow the val versus base +/- offset comparison to proceed according to the normal rules of IEEE arithmetic; however, we must do something special for the corner cases where base +/- offset would produce NaN due to subtracting two like-signed infinities. That corresponds to asking which values infinitely precede +inf or infinitely follow -inf, which should certainly be true of any finite value or of the opposite-signed infinity. After some discussion it seems that the best decision is to make it true of the same-signed infinity as well, ie, just return constant TRUE if the calculation would produce a NaN. (We could write this with a bit less code by subtracting anyway, and then checking for a NaN result. However, I prefer this formulation because it'll be easier to transpose into numeric.c.) Although this seems like clearly a bug fix with respect to finite values, it is less obviously correct for infinite values. Between that and the fact that the whole issue only arises for very strange window specifications (e.g. RANGE BETWEEN 'inf' PRECEDING AND 'inf' PRECEDING), I'll desist from back-patching. Noted by Dean Rasheed. Discussion: https://postgr.es/m/3393130.1594925893@sss.pgh.pa.us
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: https://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 https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.