TDB_DATA typedef if you want portability between the two.
- tdb2 functions return 0 on success, and a negative error on failure,
- whereas tdb1 functions returned 0 on success, and -1 on failure. tdb1
- then used tdb_error() to determine the error.
+ whereas tdb1 functions returned 0 on success, and -1 on failure.
+ tdb1 then used tdb_error() to determine the error; this is also
+ supported in tdb2 to ease backwards compatibility, though the other
+ form is preferred.
- tdb2's tdb_fetch() returns an error, tdb1's returned the data directly
(or tdb_null, and you were supposed to check tdb_error() to find out why).
tdb_lockall_read(): child must call tdb_unlockall_read()
tdb_chainlock(): child must call tdb_chainunlock()
tdb_parse() callback: child must return from tdb_parse()
+
+- tdb2 will not open a non-tdb file, even if O_CREAT is specified.
+
+- There is no tdb_traverse_read. For operating on TDB1 files, you can
+ simulate it by tdb_add_flag(tdb, TDB_RDONLY); tdb_traverse();
+ tdb_remove_flag(tdb, TDB_RDONLY). This may be desirable because
+ traverse on TDB1 files use a write lock on the entire database
+ unless it's read-only.
+
+- Failure inside a transaction (such as a lock function failing) does
+ not implicitly cancel the transaction; you still need to call
+ tdb_transaction_cancel().
+
+TDB1 Compatibility:
+
+- tdb2's offers a tdb1_incompatible_hash function, which is the same
+ as the default hash with the TDB_INCOMPATIBLE_HASH flag. There is
+ no way of marking an old TDB incompatible with versions < 1.2.6
+ while using any other hash.
+
+- The TDB_ATTRIBUTE_TDB1_HASHSIZE attribute can be used to control the
+ hash size, but only when creating (ie. O_CREAT) a TDB1
+ (ie. TDB_VERSION1).
+
+- There is no TDB_CLEAR_IF_FIRST flag; it has severe scalability and
+ API problems. If necessary, you can emulate this by using the open
+ hook and placing a 1-byte lock at offset 4. If your program forks,
+ you will need to place this lock again in the child.