Konstantin Andreev wrote:
Hi,
I am contemplating the mdb search mechanics, and puzzled by "missing parent" check in mdb_idscopes():
| /* If we didn't advance, some parent is missing */ | if ( id == prev ) | return MDB_NOTFOUND;
where "id" and "prev" are parent and child ids that come from the same "UP" ( child -> parent ) record of "dn2id" table. Here is a source code approximation for easier reading:
| MDB_val key = { sizeof(ID), & id }, data; | mdb_cursor_get( "dn2id", key, data, MDB_SET ); | // reading last sizeof(ID) bytes of data.mv_data | ID prev = *(ID *)(data.mv_data + data.mv_size - sizeof(ID));
IIUC, there is no records in "dn2id" where parent and child ids are the same. There is no by construction, except "super-root", where both ids are zeros, but zero id doesn't follow this execution path.
So, how may [id == prev] occur? Could you, please, explain?
The check came from 5a08b661 and 437f21b commits (ITS#7705,#7800 fix ...), I have read both, but they haven't helped either.
If the checks in http://www.openldap.org/devel/gitweb.cgi?p=openldap.git;a=blob;f=servers/sla... don't find a result, then id doesn't get advanced any further. This can happen in a pagedResults search when the underlying set of entries changes between page requests.
Regard, Konstantin.