9662143f0c
The regex code didn't have any provision for query cancel; which is unsurprising given its non-Postgres origin, but still problematic since some operations can take a long time. Introduce a callback function to check for a pending query cancel or session termination request, and call it in a couple of strategic spots where we can make the regex code exit with an error indicator. If we ever actually split out the regex code as a standalone library, some additional work will be needed to let the cancel callback function be specified externally to the library. But that's straightforward (certainly so by comparison to putting the locale-dependent character classification logic on a similar arms-length basis), and there seems no need to do it right now. A bigger issue is that there may be more places than these two where we need to check for cancels. We can always add more checks later, now that the infrastructure is in place. Since there are known examples of not-terribly-long regexes that can lock up a backend for a long time, back-patch to all supported branches. I have hopes of fixing the known performance problems later, but adding query cancel ability seems like a good idea even if they were all fixed. |
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| README.git | ||
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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/.