Re: MDB_INTEGERDUP in back-mdb's indexer for attr-tables.

Леонид Юрьев wrote: > > Hi, Howard. > > I would like to refine my question. > > Currently I develop a mdb_chk tool for deep check LMDB-files, like a fsck > tool. > It is needed for us, but let this stay aside for now. > > On some step I plan to check the size of each key in each DBI with > MDB_INTEGERKEY and/or MDB_INTEGERDUP flags. > > Initially I assumed - if one of these flags is set, the the length of > all keys must be sizeof(int) or sizeof(long). As will be used the > corresponding comparison functions (mdb_cmp_int, mdb_cmp_long) , which > can handle only keys of such sizes. > > But this approach has failed. A dbi-tables created for attr by > mdb_attr_dbs_open() have MDB_DUPSORT|MDB_DUPFIXED|MDB_INTEGERDUP flags > and may contain records with a 5-byte keys. For instance as the > 'entryCSN'. > > Later you have written that MDB_INTEGERDUP is required. > > Now I do not understand how it all works: > - MDB_INTEGERDUP is set for attr tables. > - indexer could create a 5-byte keys. > - mdb-backend set custom comparison function only for MDB_DN2ID table. > - under debugger I see that md_dcmp is pointed to the default. > - assert for key-size in default comparators was not failed while "make > test". > - all test are passed without MDB_INTEGERDUP. > - but you told MDB_INTEGERDUP is necessary > > So, > - how and when MDB_INTEGERDUP will have an impact? > - in which cases keys in the table definitely should be sizeof(int) or > sizeof(long)? MDB_INTGERKEY means the *keys* must be int/long. MDB_INTEGERDUP means the *values* must be int/long. When either flag is set, all of the corresponding (keys|values) in the DB must be the same size. The indexer only uses MDB_INTEGERDUP - it doesn't care what size the keys are, but the values must be (longs in this case). -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/