postgres

History

Tom Lane 137935bd11 Don't reduce output request size on non-Unix-socket connections. Traditionally, libpq's pqPutMsgEnd has rounded down the amount-to-send to be a multiple of 8K when it is eagerly writing some data. This still seems like a good idea when sending through a Unix socket, as pipes typically have a buffer size of 8K or some fraction/multiple of that. But there's not much argument for it on a TCP connection, since (a) standard MTU values are not commensurate with that, and (b) the kernel typically applies its own packet splitting/merging logic. Worse, our SSL and GSSAPI code paths both have API stipulations that if they fail to send all the data that was offered in the previous write attempt, we mustn't offer less data in the next attempt; else we may get "SSL error: bad length" or "GSSAPI caller failed to retransmit all data needing to be retried". The previous write attempt might've been pqFlush attempting to send everything in the buffer, so pqPutMsgEnd can't safely write less than the full buffer contents. (Well, we could add some more state to track exactly how much the previous write attempt was, but there's little value evident in such extra complication.) Hence, apply the round-down only on AF_UNIX sockets, where we never use SSL or GSSAPI. Interestingly, we had a very closely related bug report before, which I attempted to fix in commit `d053a879b`. But the test case we had then seemingly didn't trigger this pqFlush-then-pqPutMsgEnd scenario, or at least we failed to recognize this variant of the bug. Bug: #18907 Reported-by: Dorjpalam Batbaatar <htgn.dbat.95@gmail.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/18907-d41b9bcf6f29edda@postgresql.org Backpatch-through: 13		7 months ago
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po	Translation updates	8 months ago
t	Replace deprecated log_connections values in docs and tests	8 months ago
test	meson: Add missing dependencies for libpq tests	11 months ago
.gitignore	Run tap tests in src/interfaces/libpq.	4 years ago
Makefile	oauth: Correct missing comma in Requires.private	8 months ago
README	…
exports.txt	oauth: Move the builtin flow into a separate module	8 months ago
fe-auth-oauth.c	oauth: Limit JSON parsing depth in the client	8 months ago
fe-auth-oauth.h	oauth: Move the builtin flow into a separate module	8 months ago
fe-auth-sasl.h	libpq: Handle asynchronous actions during SASL	11 months ago
fe-auth-scram.c	Use 'void ' for arbitrary buffers, 'uint8 ' for byte arrays	8 months ago
fe-auth.c	Use 'void ' for arbitrary buffers, 'uint8 ' for byte arrays	8 months ago
fe-auth.h	Add support for OAUTHBEARER SASL mechanism	11 months ago
fe-cancel.c	Use 'void ' for arbitrary buffers, 'uint8 ' for byte arrays	8 months ago
fe-connect.c	Fix assorted new memory leaks in libpq.	8 months ago
fe-exec.c	With GB18030, prevent SIGSEGV from reading past end of allocation.	8 months ago
fe-gssapi-common.c	Update copyright for 2025	1 year ago
fe-gssapi-common.h	Update copyright for 2025	1 year ago
fe-lobj.c	libpq: Deprecate pg_int64.	10 months ago
fe-misc.c	Don't reduce output request size on non-Unix-socket connections.	7 months ago
fe-print.c	Update copyright for 2025	1 year ago
fe-protocol3.c	Use 'void ' for arbitrary buffers, 'uint8 ' for byte arrays	8 months ago
fe-secure-common.c	Update copyright for 2025	1 year ago
fe-secure-common.h	Update copyright for 2025	1 year ago
fe-secure-gssapi.c	Don't reduce output request size on non-Unix-socket connections.	7 months ago
fe-secure-openssl.c	Quote filename in error message	9 months ago
fe-secure.c	Update copyright for 2025	1 year ago
fe-trace.c	libpq: Trace all NegotiateProtocolVersion fields	10 months ago
legacy-pqsignal.c	Avoid symbol collisions between pqsignal.c and legacy-pqsignal.c.	12 months ago
libpq-events.c	Update copyright for 2025	1 year ago
libpq-events.h	Update copyright for 2025	1 year ago
libpq-fe.h	libpq: Deprecate pg_int64.	10 months ago
libpq-int.h	Use 'void ' for arbitrary buffers, 'uint8 ' for byte arrays	8 months ago
meson.build	oauth: Move the builtin flow into a separate module	8 months ago
nls.mk	oauth: Move the builtin flow into a separate module	8 months ago
pg_service.conf.sample	…
pqexpbuffer.c	Update copyright for 2025	1 year ago
pqexpbuffer.h	Update copyright for 2025	1 year ago
pthread-win32.c	Update copyright for 2025	1 year ago
win32.c	Update copyright for 2025	1 year ago
win32.h	Recognize network-failure errnos as indicating hard connection loss.	5 years ago

README

src/interfaces/libpq/README

This directory contains the C version of Libpq, the POSTGRES frontend library.