postgres_fdw: Fix corner cases in transaction mode propagation. This commit addresses the following issues in commit de28140de:
* When the local transaction was DEFERRABLE, begin_remote_xact() started a remote transaction in the same mode without checking the remote server version. Since DEFERRABLE is supported only in v9.1 and later, this would cause a syntax error on older remote servers. Fix this by propagating the mode only to remote servers that support it. * pgfdw_xact_callback() committed remote transactions without synchronizing the read-only mode. If the local transaction had become READ ONLY since the last remote operation, this would cause deferred triggers on remote servers to still run in READ WRITE mode. Fix this by synchronizing the mode at commit time. * The documentation did not match the actual implementation. Update the documentation to reflect the implementation. Reported-by: Fujii Masao <[email protected]> Author: Etsuro Fujita <[email protected]> Reviewed-by: Matheus Alcantara <[email protected]> Discussion: https://postgr.es/m/CAHGQGwE4UMaWGOZq1Z7YUTUSg-CgL4yAzO5YaGwTZe1-6Pjg2g%40mail.gmail.com Backpatch-through: 19 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/d6393fc40a59830a88a79bdf08e962122fa9c631 Modified Files -------------- contrib/postgres_fdw/connection.c | 54 +++++++++++++++++++++++--- contrib/postgres_fdw/expected/postgres_fdw.out | 30 ++++++++++++-- contrib/postgres_fdw/sql/postgres_fdw.sql | 30 ++++++++++++-- doc/src/sgml/postgres-fdw.sgml | 15 +++---- 4 files changed, 106 insertions(+), 23 deletions(-)
