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Re: bdb backend: memp_trickle

On Tue, 15 Feb 2005, Howard Chu wrote:

>In general, back-hdb and back-bdb are identical. The only difference is
>how the dn2id index is structured, which allows back-hdb to support
>subtree renames. Of course none of this is relevant to your original
>question regarding memp_trickle.

I'm beginning to see.  I just read your presentations and emails.  So this
is your baby, eh?

>>I guess I still have the same question for hdb, though.  Does it somehow
>>trickle the in-memory changes out to disk or does it only flush
>>periodically at a checkpoint or when closing the environment?
>Only at checkpoint / close.

Okay, so hdb is overall more consistent in performance and more efficient
at making changes, but is still going to have the same behavior as far as
writing the changes out.  It just sounds like it will be writing less data
to the id2entry file so it should go faster.  Is that about right?

I like the idea of just running my own trickle thread.  I just wanted to
hear it from someone with more bdb experience than me.

I see mention of the need for using larger IDL cache.  Is this something
that is done only at slapd compile time affecting memory allocation within
slapd or is there a DB_CONFIG tunable for the whole db environment?  I
couldn't find any mention of IDL cache on sleepycat.com...  In other
words, are the notations of the need for more IDL cache merely an
observation or a suggestion to the user?

Thanks, Howard and Quanah.  Your posts are always informative.

Eric Irrgang - UT Austin ITS Unix Systems - (512)475-9342