Instead of executing each UPDATEBATCH update in a separate DB4 transaction, do them all in a single transaction.  This greatly reduces the amount of synchronous disk i/o that DB4 might be tempted to do and improve performance; Jeremy's real world experiments with syncd appear to confirm this.  We can also try increasing the batching in libadb.h.
Instead of executing each UPDATEBATCH update in a separate DB4 transaction,
do them all in a single transaction.  This greatly reduces the amount
of synchronous disk i/o that DB4 might be tempted to do and improve
performance; Jeremy's real world experiments with syncd appear to confirm
this.  We can also try increasing the batching in libadb.h.

weidezhang/dht,weidezhang/dht,weidezhang/dht,weidezhang/dht,sit/dht,weidezhang/dht,sit/dht,sit/dht,sit/dht,sit/dht