On 24/03/2015 6:38 AM, Howard Chu wrote: > Geoff Swan wrote: >> I had to duplicate an LMDB database for replication recently, and >> used mdb_copy to do so. >> One server is using the original data.mdb database (which is sparse) > and the other is using the mdb_copy non-sparse data.mdb file. > > If you specified no special options, the file produced by mdb_copy is > identical to the original - it will also be sparse if the original is. > >> The two servers are identical (hardware, OS, software and > configuration). OpenLDAP-2.4.39 is being used, 64 bit Linux OS. mdb_stat > shows the map size as the same, which is expected. >> >> Will the use of the non-sparse file cause any performance issues? > > Question is irrelevant since both are sparse files. Thanks for the clarification Howard. The data file from the mdb_copy snapshot was transferred over the network to the other server using scp, which I understand does not recognise sparse files, so the copy is likely to be non-sparse. I guess this would be considered a corruption and best to start with a fresh copy?
> >> The reason for asking is that I am seeing a difference in search >> times between the two. >> With 20 million objects, a search on modifyTimestamp (which is >> indexed) gives: >> server 1: approx 1s >> server 2: approx 60s >> >> server 2 started with the same search time as server 1 when the > databases were originally copied, but has slowly increased its search > time over about a week for this same search. > > Look at disk I/O and memory usage, the LMDB file itself has no bearing > here. >
