0b78106cd4
expandRTE() and get_rte_attribute_type() reported the exprType() and exprTypmod() values of the expressions in the first row of the VALUES as being the column type/typmod returned by the VALUES RTE. That's fine for the data type, since we coerce all expressions in a column to have the same common type. But we don't coerce them to have a common typmod, so it was possible for rows after the first one to return values that violate the claimed column typmod. This leads to the incorrect result seen in bug #14448 from Hassan Mahmood, as well as some other corner-case misbehaviors. The desired behavior is the same as we use in other type-unification cases: report the common typmod if there is one, but otherwise return -1 indicating no particular constraint. It's cheap for transformValuesClause to determine the common typmod while transforming a multi-row VALUES, but it'd be less cheap for expandRTE() and get_rte_attribute_type() to re-determine that info every time they're asked --- possibly a lot less cheap, if the VALUES has many rows. Therefore, the best fix is to record the common typmods explicitly in a list in the VALUES RTE, as we were already doing for column collations. This looks quite a bit like what we're doing for CTE RTEs, so we can save a little bit of space and code by unifying the representation for those two RTE types. They both now share coltypes/coltypmods/colcollations fields. (At some point it might seem desirable to populate those fields for all RTE types; but right now it looks like constructing them for other RTE types would add more code and cycles than it would save.) The RTE change requires a catversion bump, so this fix is only usable in HEAD. If we fix this at all in the back branches, the patch will need to look quite different. Report: https://postgr.es/m/20161205143037.4377.60754@wrigleys.postgresql.org Discussion: https://postgr.es/m/27429.1480968538@sss.pgh.pa.us |
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README
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/.