Thanks, Howard. It would be nice if some clarification, like these, will be in the lmdb.h.
Leonid. 2015-05-01 4:42 GMT+03:00 Howard Chu <h...@symas.com>: > 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/
