618c16707a
Since commit ffa2e4670, libpq accumulates text in conn->errorMessage across a whole query cycle. In some situations, we may report more than one error event within a cycle: the easiest case to reach is where we report a FATAL error message from the server, and then a bit later we detect loss of connection. Since, historically, each error PGresult bears the entire content of conn->errorMessage, this results in duplication of the FATAL message in any output that concatenates the contents of the PGresults. Accumulation in errorMessage still seems like a good idea, especially in view of the number of places that did ad-hoc error concatenation before ffa2e4670. So to fix this, let's track how much of conn->errorMessage has been read out into error PGresults, and only include new text in later PGresults. The tricky part of that is to be sure that we never discard an error PGresult once made (else we'd risk dropping some text, a problem much worse than duplication). While libpq formerly did that in some code paths, a little bit of rearrangement lets us postpone making an error PGresult at all until we are about to return it. A side benefit of that postponement is that it now becomes practical to return a dummy static PGresult in cases where we hit out-of-memory while trying to manufacture an error PGresult. This eliminates the admittedly-very-rare case where we'd return NULL from PQgetResult, indicating successful query completion, even though what actually happened was an OOM failure. Discussion: https://postgr.es/m/ab4288f8-be5c-57fb-2400-e3e857f53e46@enterprisedb.com
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/.