Full_Name: Hallvard B Furuseth Version: mdb.master, 4c8f57615c5ca7b014c038e59c1045182e74f5ad OS: Linux x86_64 URL: ftp://ftp.openldap.org/incoming/Hallvard-Furuseth-growth-131223.c Submission from: (NULL) (81.191.45.35) Submitted by: hallvard

A non-LEAF2 sub-page grows if you put() a data item which already exists. The space remains unused while the sub-page exists. (A LEAF2 page grows reusable space, and only if it is full.)

Demo program enclosed. Edit mdb.c to set mdb_debug=1 and build with -DMDB_DEBUG. Watch the 1st DPRINTF() in mdb_node_add():

bash$ ./a.out 2>&1 | perl -lne '/add to (.*) key size/ && print $1' leaf page 2 index 0, data size 404 # node with 1st item leaf page 2 index 0, data size 840 # convert to sub-page for 2nd item leaf sub-page 2 index 0, data size 0 leaf sub-page 2 index 1, data size 0 leaf page 2 index 0, data size 1250 # space for re-adding 2nd item leaf page 2 index 0, data size 1660 # space for re-adding 2nd item leaf page 2 index 0, data size 48 # ...too big, moved to sub-DB.

Fix: lmdb could position cursor+xcursor fully before spill/touch, with an MDB_GET_BOTH variant which returns different codes for "no such key" and "no such data". And position it before MDB_MULTIPLE loops up. The current comparisons to see if the data item exists, go away. Maybe mdb_cursor_put() gets split in several functions, since much of the work in the recursive put()s will be unneeded.