716ea626a8
If construct_array() or construct_md_array() were given a dimension of zero, they'd produce an array that contains no elements but has positive dimension. This violates a general expectation that empty arrays should have ndims = 0; in particular, while arrays like this print as empty, they don't compare equal to other empty arrays. Up to now we've expected callers to avoid making such calls and instead be careful to call construct_empty_array() if there would be no elements. But this has always been an easily missed case, and we've repeatedly had to fix callers to do it right. In bug #14826, Erwin Brandstetter pointed out yet another such oversight, in ts_lexize(); and a bit of examination of other call sites found at least two more with similar issues. So let's fix the problem centrally and permanently by changing these two functions to construct a proper zero-D empty array whenever the array would be empty. This renders a few explicit calls of construct_empty_array() redundant, but the only such place I found that really seemed worth changing was in ExecEvalArrayExpr(). Although this fixes some very old bugs, no back-patch: the problem is pretty minor and the risk of changing behavior seems to outweigh the benefit in stable branches. Discussion: https://postgr.es/m/20170923125723.1448.39412@wrigleys.postgresql.org Discussion: https://postgr.es/m/20570.1506198383@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/.