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Base de données relationnelle
65ce07e020
In particular, make it possible to prove/refute "x IS NULL" and "x IS NOT NULL" predicates from a clause involving a ScalarArrayOpExpr even when we are unable or unwilling to deconstruct the expression into an AND/OR tree. This avoids a former unexpected degradation of plan quality when the size of an ARRAY[] expression or array constant exceeded the arbitrary MAX_SAOP_ARRAY_SIZE limit. For IS-NULL proofs, we don't really care about the values of the individual array elements; at most, we care whether there are any, and for some common cases we needn't even know that. The main user-visible effect of this is to let the optimizer recognize applicability of partial indexes with "x IS NOT NULL" predicates to queries with "x IN (array)" clauses in some cases where it previously failed to recognize that. The structure of predtest.c is such that a bunch of related proofs will now also succeed, but they're probably much less useful in the wild. James Coleman, reviewed by David Rowley Discussion: https://postgr.es/m/CAAaqYe8yKSvzbyu8w-dThRs9aTFMwrFxn_BkTYeXgjqe3CbNjg@mail.gmail.com |
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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: 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/.