kkalev at noc.ntua.gr
Tue Dec 11 12:31:16 CET 2012
On 11/12/2012 11:56 πμ, Phil Mayers wrote:
> On 12/10/2012 03:27 PM, John Dennis wrote:
>> On 12/09/2012 07:33 PM, Arran Cudbard-Bell wrote:
>>> Just pushed up a few patches to add LDAP accounting.
>> Just out of curiosity why are we adding support for "worst practice",
>> shouldn't we be encouraging "best practice" via the choice of supported
>> Maintaining accounting data in LDAP is an abuse of the LDAP design goals
>> of "frequent lookup, infrequent modification". Databases were designed
>> for the type of data management that radius accounting involves,
>> directories were not. Accounting should be in a database, not a
>> directory. Directories were designed to solve different problems.
> This is a bit OT, but I'm honestly curious here...
> I've heard this sort of general statement about directories
> (specifically LDAP) being suitable for read-heavy workloads, and SQL
> being suitable for read/write-heavy, for well over 15 years now.
> No-one has ever adequately explained to me *why* sending an LDAP write
> op PDU is somehow different than sending an LDAP read op PDU.
> It may be that all or most LDAP *implementations* are relatively slow
> at writes, but if so, it doesn't follow that this *must* be the case.
> Obviously writes are slower than reads in LDAP, but that's true of
> almost any datastore backed by permanent storage. However, having done
> mass/bulk LDAP updates to OpenLDAP (and on older versions) I've found
> it pretty snappy. So I'd love to know why this is an "abuse" any more
> than using any other protocol in unanticipated-but-compliant ways.
It's not an abuse but mainly not 'best-practice'. A well configured LDAP
server with enough cache memory will be bottlenecked by memory and
network speed and not by underlying I/O. A frequent writes strategy
invalidates most of these performance gains since an entry write will
invalidate entry and database cache entries.
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