16 Nov
2011
16 Nov
'11
8:07 a.m.
Hello,
On 11/15/11 12:59 PM, Juha Heinanen wrote:
Adding a record (i.e., prefix/value) in a tree should be
fast if
building the missing sub-tree part of it and then just linking it to the
main tree. Removing might need more time, a solution for it can be just
setting the value to NULL and keep the tree structure..
Cheers,
Daniel
--
Daniel-Constantin Mierla -- http://www.asipto.com
Kamailio Advanced Training, Dec 5-8, Berlin: http://asipto.com/u/kat
http://linkedin.com/in/miconda -- http://twitter.com/miconda
Daniel-Constantin Mierla writes:
for large trees it would be not possible to have a lock for each node,
there will be too many and different operating systems have limits. On a
hash table there is a lock per slot, no matter how many items are in the
table. In a tree is hard to define a set of locks and just going with
one per node is not that feasible. For eaxample one record with prefix
0123456789 creates 10 nodes, then some nodes are reused, but still there
are a greater or equal number of nodes than the number of records loaded.
I assume many times the changes will be somewhere
down the tree, since
the first part of the number is usually the same (e.g., country code and
operator prefix). To update the tree at runtime, while there are reads
on it, there must be used a lock to be safe an consistent. If you do lot
of writes and very often, then you keep the tree structure locked a lot,
slowing the search.
daniel,
could the lock be from the node that requires modification downwards,
which would leave all other branches unlocked? Can you estimate the number of writes and how
often they would be on a
daily basis? There might be other solutions to look at, if writes are
very often.
i was thinking that perhaps mtree would be used to store numbers that
are ported to other operators instead of the current carrier route pdb
server, where the whole mmap file needs to be reloaded. in that
application i would imagine a few hundred updates per hour, but many of
them would only affect the value associated with the node, not the
structure of the three.