b4721f3950
If a failure happens when a transaction is starting between the moment the transaction status is changed from TRANS_DEFAULT to TRANS_START and the moment the current user ID and security context flags are fetched via GetUserIdAndSecContext(), or before initializing its basic fields, then those may get reset to incorrect values when the transaction aborts, leaving the session in an inconsistent state. One problem reported is that failing a starting transaction at the first query of a session could cause several kinds of system crashes on the follow-up queries. In order to solve that, move the initialization of the transaction state fields and the call of GetUserIdAndSecContext() in charge of fetching the current user ID close to the point where the transaction status is switched to TRANS_START, where there cannot be any error triggered in-between, per an idea of Tom Lane. This properly ensures that the current user ID, the security context flags and that the basic fields of TransactionState remain consistent even if the transaction fails while starting. Reported-by: Richard Guo Diagnosed-By: Richard Guo Author: Michael Paquier Reviewed-by: Tom Lane Discussion: https://postgr.es/m/CAN_9JTxECSb=pEPcb0a8d+6J+bDcOZ4=DgRo_B7Y5gRHJUM=Rw@mail.gmail.com Backpatch-through: 9.4 |
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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: 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/.