RE: MDB_BAD_VALSIZE error

[Chris Card <ctcard@hotmail.com>]

Howard Chu wrote:
> Subject: Re: MDB_BAD_VALSIZE error
>
> Chris Card wrote:
>> Hi All,
>>
>> I'm running openldap 2.4.36 on centos 6.3, 64 bit.
>>
>> I'm finally trying out MDB as a replacement for BDB in our openldap setup, and I've noticed that I'm getting MDB_BAD_VALSIZE errors when adding some DNs, which could be added without error when using BDB as the backend:
>>
>> 52e9170b <= mdb_dn2id_add 0x5da55e: -30781
>> 52e9170b mdb_add: dn2id_add failed: MDB_BAD_VALSIZE: Too big key/data, key is empty, or wrong DUPFIXED size (-30781)
>>
>> Looking at the code, it seems that this error happens when MDB_MAXKEYSIZE is exceeded and MDB_MAXKEYSIZE is set to 511 as far as I can see.
>>
>> The DNs which are giving this error are between 232 and 255 characters long.
>>
>> Does the MDB backend have an implicit limit on the length of valid DNs?
>
> slapd has a limit of 8192 bytes on DNs. RDNs in back-mdb are limited by
> MDB_MAXKEYSIZE.
>
>> Can this be increased (by changing MDB_MAXKEYSIZE) and if so, what is the longest DN which can be supported by the MDB backend?
>
> The longest DN supported is 8192 bytes. The longest RDN would be something
> close to one half of MDB_MAXKEYSIZE.
>
Thanks, I understand now. The longest RDN appears to be 245 characters on my system. Can MDB_MAXKEYSIZE be increased? If so, what is the maximum safe value?

Chris