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Heikki Linnakangas
3f32804918
The expression (len_diff * 10 * (an + 1)) used as the return value of ltree_compare() is computed at int32 width. With LTREE_MAX_LEVELS = 65535, the product can exceed INT32_MAX once an ltree has more than ~14,653 levels, which causes the result to wrap and invert its sign. That corrupts btree ordering as well as the "magnitude" consumed by ltree_penalty() for GiST page splits. To fix, split ltree_compare() into two functions. The new ltree_compare_distance() function returns a float, which won't overflow. It's used by the ltree_penalty() caller. All the other callers only care about the sign of the return value, i.e. which of the arguments is greater, so change ltree_compare() to not multiply the result with (10 * (an + 1)), which avoids the overflow for those callers. Existing btree or GiST indexes on ltree columns containing values with more than ~14,653 levels may be corrupt and should be REINDEXed. Add a regression test based on the reporter's PoC. Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com> Reported-by: 王跃林 <violin0613@tju.edu.cn> Discussion: https://www.postgresql.org/message-id/AI6AnABgKW93Qbx1jVzi84r9.8.1781322625756.Hmail.3020001251%40tju.edu.cn Backpatch-through: 14
The PostgreSQL contrib tree
---------------------------
This subtree contains porting tools, analysis utilities, and plug-in
features that are not part of the core PostgreSQL system, mainly
because they address a limited audience or are too experimental to be
part of the main source tree. This does not preclude their
usefulness.
User documentation for each module appears in the main SGML
documentation.
When building from the source distribution, these modules are not
built automatically, unless you build the "world" target. You can
also build and install them all by running "make all" and "make
install" in this directory; or to build and install just one selected
module, do the same in that module's subdirectory.
Some directories supply new user-defined functions, operators, or
types. To make use of one of these modules, after you have installed
the code you need to register the new SQL objects in the database
system by executing a CREATE EXTENSION command. In a fresh database,
you can simply do
CREATE EXTENSION module_name;
See the PostgreSQL documentation for more information about this
procedure.