malyn@strangeGizmo.com wrote:

Full_Name: Michael Alyn Miller Version: LMDB 0.9.14, Git head OS: Windows 8.1 x64, NixOS 14.12 x64 URL: ftp://ftp.openldap.org/incoming/michael-alyn-miller-151005.c Submission from: (NULL) (96.251.78.237)

I have a helper library that sits on top of LMDB and testing some of the abstractions in that library has exposed a bug in LMDB related to deleting items while inside of a cursor. I have reduced the repro down to a test case that operates directly against LMDB.

The test in question adds three groups of keys to the database (each with a different prefix) and then deletes the third group of keys. The deletion is done by scanning all of the keys with that prefix using a cursor. mdb_cursor_del works correctly and deletes only the targeted keys, whereas mdb_del causes nine extra keys (not in that group/prefix) to be deleted.

I have tested this code against LMDB 0.9.14 and Git head 8b46dcc. Please let me know if you need any additional information. Thank you for your time!

Unable to reproduce.

violino:~/OD/mdb/libraries/liblmdb> gcc -g -c michael-alyn-miller-151005.c violino:~/OD/mdb/libraries/liblmdb> gcc -o mic michael-alyn-miller-151005.o -pthread liblmdb.a violino:~/OD/mdb/libraries/liblmdb> ./mic Num items after deletion using mdb_cursor_del: 44 (correct) Num items after deletion using mdb_del: 44 (correct) violino:~/OD/mdb/libraries/liblmdb> git log commit 8b46dcc26d1e9897ab1da3a4a164cad4a4479a52 Author: Howard Chu hyc@openldap.org Date: Sun Oct 4 01:56:25 2015 +0100

ITS#8258 fix rebalance/split

The tree height can also increase during rebalance, not just shrink. This can happen if update_key needs to split a parent branch page.