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ae47f8a966
Commits f92944137 et al. made IsInTransactionBlock() set the
XACT_FLAGS_NEEDIMMEDIATECOMMIT flag before returning "false",
on the grounds that that kept its API promises equivalent to those of
PreventInTransactionBlock(). This turns out to be a bad idea though,
because it allows an ANALYZE in a pipelined series of commands to
cause an immediate commit, which is unexpected.
Furthermore, if we return "false" then we have another issue,
which is that ANALYZE will decide it's allowed to do internal
commit-and-start-transaction sequences, thus possibly unexpectedly
committing the effects of previous commands in the pipeline.
To fix the latter situation, invent another transaction state flag
XACT_FLAGS_PIPELINING, which explicitly records the fact that we
have executed some extended-protocol command and not yet seen a
commit for it. Then, require that flag to not be set before allowing
InTransactionBlock() to return "false".
Having done that, we can remove its setting of NEEDIMMEDIATECOMMIT
without fear of causing problems. This means that the API guarantees
of IsInTransactionBlock now diverge from PreventInTransactionBlock,
which is mildly annoying, but it seems OK given the very limited usage
of IsInTransactionBlock. (In any case, a caller preferring the old
behavior could always set NEEDIMMEDIATECOMMIT for itself.)
For consistency also require XACT_FLAGS_PIPELINING to not be set
in PreventInTransactionBlock. This too is meant to prevent commands
such as CREATE DATABASE from silently committing previous commands
in a pipeline.
Per report from Peter Eisentraut. As before, back-patch to all
supported branches (which sadly no longer includes v10).
Discussion: https://postgr.es/m/65a899dd-aebc-f667-1d0a-abb89ff3abf8@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/.