fd333bc763
Over the years we've accreted quite a few special variables that are predefined in plpgsql trigger functions. The cost of initializing these variables to their defined values turns out to be a significant part of the runtime of simple triggers; but, undoubtedly, most real-world triggers never examine the values of most of these variables. To improve matters, invent the notion of a variable that has a "promise" attached to it, specifying which of the predetermined values should be assigned to the variable if anything ever reads it. This eliminates all the unneeded startup overhead, in return for a small penalty on accesses to these variables. Tom Lane, reviewed by Pavel Stehule Discussion: https://postgr.es/m/11986.1514407114@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/.