On Mon, 2015-05-18 at 23:03 +0200, Hallvard Breien Furuseth wrote: > On 12/05/15 19:36, Howard Chu wrote: > > Dmytro Milinevskyy wrote: > > > Basically I need to have an opportunity to call mdb_get while in > > > write > > > transaction. > > > The sequence is smth like: > > > - txn = mdb_txn_begin(flags=0) > > > for i in 0..x: > > > - v = mdb_get(txn, i) > > > - mdb_put(txn, x+i, v) > > > - mdb_put(txn, i, v+1) > > > - mdb_txn_commit(txn) > > > > > > Will it be always valid data? > > > > Yes. > > ...No. I expect he means v = the MDB_val returned by mdb_get(). > mdb_put() can modify the data it points at. > > See the MDB_val documentation in ldmb.h: > * Values returned from the database are valid only until a > subsequent > * update operation, or the end of the transaction. Do not modify or > * free them, they commonly point into the database itself. >
What exactly does a subsequent update operation mean? Overwriting the value of the same key, or any mdb_put or mdb_cursor_put operation at all, regardless of which key they touch?