Tom Lane 5c1b7edc23 Fix get_actual_variable_range() to cope with broken HOT chains. ... Commit 3ca930fc3 modified get_actual_variable_range() to use a new "SnapshotNonVacuumable" snapshot type for selecting tuples that it would consider valid. However, because that snapshot type can accept recently-dead tuples, this caused a bug when using a recently-created index: we might accept a recently-dead tuple that is an early member of a broken HOT chain and does not actually match the index entry. Then, the data extracted from the heap tuple would not necessarily be an endpoint value of the column; it could even be NULL, leading to get_actual_variable_range() itself reporting "found unexpected null value in index". Even without an error, this could lead to poor plan choices due to an erroneous notion of the endpoint value. We can improve matters by changing the code to use the index-only scan technique (which didn't exist when get_actual_variable_range was originally written). If any of the tuples in a HOT chain are live enough to satisfy SnapshotNonVacuumable, we take the data from the index entry, ignoring what is in the heap. This fixes the problem without changing the live-vs-dead-tuple behavior from what was intended by commit 3ca930fc3. A side benefit is that for static tables we might not have to touch the heap at all (when the extremal value is in an all-visible page). In addition, we can save some overhead by not having to create a complete ExecutorState, and we don't need to run FormIndexDatum, avoiding more cycles as well as the possibility of failure for indexes on expressions. (I'm not sure that this code would ever be used to determine the extreme value of an expression, in the current state of the planner; but it's definitely possible that lower-order columns of the selected index could be expressions. So one could construct perhaps-artificial examples in which the old code unexpectedly failed due to trying to compute an expression's value for a now-dead row.) Per report from Manuel Rigger. Back-patch to v11 where commit 3ca930fc3 came in. Discussion: https://postgr.es/m/CA+u7OA7W4NWEhCvftdV6_8bbm2vgypi5nuxfnSEJQqVKFSUoMg@mail.gmail.com		2019-07-12 16:24:59 -04:00
..
backend	Fix get_actual_variable_range() to cope with broken HOT chains.	2019-07-12 16:24:59 -04:00
bin	Fix tab completion of "SET variable TO|=" to not offer bogus completions.	2019-07-02 13:35:14 -04:00
common	Tolerate EINVAL when calling fsync() on a directory.	2019-02-24 23:51:54 +13:00
fe_utils	Fix translation of special characters in psql's LaTeX output modes.	2018-11-26 17:32:51 -05:00
include	Don't read fields of a misaligned ExpandedObjectHeader or AnyArrayType.	2019-06-30 17:34:20 -07:00
interfaces	Stamp 11.4.	2019-06-17 17:15:30 -04:00
makefiles	Define WIN32_STACK_RLIMIT throughout win32 and cygwin builds.	2019-04-09 08:25:42 -07:00
pl	Ensure plpgsql result tuples have the right composite type marking.	2019-07-03 18:08:53 -04:00
port	Stamp 11.4.	2019-06-17 17:15:30 -04:00
template	Yet further rethinking of build changes for macOS Mojave.	2018-11-02 18:54:00 -04:00
test	Fix RANGE partition pruning with multiple boolean partition keys	2019-07-12 19:10:12 +12:00
timezone	Portability fix for zic.c.	2019-04-26 21:20:21 -04:00
tools	Add support for Visual Studio 2019 in build scripts	2019-07-03 08:57:39 +09:00
tutorial	Update copyright for 2018	2018-01-02 23:30:12 -05:00
.gitignore
DEVELOPERS
Makefile	Fix partial-build problems introduced by having more generated headers.	2018-04-09 16:42:10 -04:00
Makefile.global.in	Consistently test for in-use shared memory.	2019-04-12 22:36:42 -07:00
Makefile.shlib	Ensure static libraries have correct mod time even if ranlib messes it up.	2018-11-29 15:53:44 -05:00
nls-global.mk	nls-global.mk: search build dir for source files, too	2016-06-07 18:55:18 -04:00