projects / thirdparty / pdns.git / blame
| Commit | Line | Data |
|---|---|---|
| c7a0a153 NC |
1 | LMDB backend |
| 2 | ============ | |
| 3 | ||
| 4 | * Native: Yes | |
| 5 | * Master: Yes | |
| 6 | * Slave: Yes | |
| 7 | * Superslave: No | |
| 8 | * Case: All lower | |
| 9 | * DNSSEC: Yes | |
| 10 | * Disabled data: No | |
| 11 | * Comments: No | |
| 12 | * Module name: lmdb | |
| 13 | * Launch name: ``lmdb`` | |
| 14 | ||
| dc4bb3b2 PD |
15 | |
| 16 | .. warning:: | |
| 17 | The LMDB backend is EXPERIMENTAL. Be prepared for incompatible changes between minor releases in the 4.2.x branch, and while tracking our git master. | |
| 18 | ||
| c7a0a153 NC |
19 | Enabling the backend |
| 20 | -------------------- | |
| 21 | ||
| 6737cb17 | 22 | When building PowerDNS yourself, append ``lmdb`` to ``--with-modules`` or ``--with-dynmodules``. It is expected that most pre-built packages contain this backend or be separately installable. |
| c7a0a153 NC |
23 | |
| 24 | ||
| 25 | Settings | |
| 26 | -------- | |
| 27 | ||
| 28 | .. _setting-lmdb-filename: | |
| 29 | ||
| 30 | ``lmdb-filename`` | |
| 31 | ^^^^^^^^^^^^^^^^^ | |
| 32 | ||
| 33 | Path to the LMDB file (e.g. */var/spool/powerdns/pdns.lmdb*) | |
| 34 | ||
| 35 | .. warning:: | |
| 36 | On systemd systems, | |
| 6737cb17 | 37 | When running PowerDNS via the provided systemd service file, `ProtectSystem <http://www.freedesktop.org/software/systemd/man/systemd.exec.html#ProtectSystem=>`_ is set to ``full``, this means PowerDNS is unable to write to e.g. ``/etc`` and ``/home``, possibly being unable to write to the LMDB database. |
| c7a0a153 NC |
38 | |
| 39 | .. _setting-lmdb-shards: | |
| 40 | ||
| 41 | ``lmdb-shards`` | |
| 42 | ^^^^^^^^^^^^^^^^^ | |
| 43 | ||
| 6737cb17 | 44 | Records database will be split into this number of shards e.g. lmdb-shards=64 |
| d3ee2140 | 45 | Default is 2 on 32 bits systems, and 64 on 64 bits systems. |
| c7a0a153 NC |
46 | |
| 47 | .. _setting-lmdb-sync-mode: | |
| 48 | ||
| 49 | ``lmdb-sync-mode`` | |
| e1885b10 | 50 | ^^^^^^^^^^^^^^^^^^ |
| c7a0a153 | 51 | |
| f61541a1 | 52 | Synchronisation mode: sync, nosync, nometasync, mapasync |
| 7055fa20 | 53 | Default: mapasync |
| c7a0a153 | 54 | |
| f61541a1 | 55 | * ``sync``: LMDB synchronous mode. Safest option, but also slightly slower. Can also be enabled with ``lmdb-sync-mode=`` |
| cbc0d0cf | 56 | * ``nosync``: don't flush systems buffers to disk when committing a transation. |
| 6737cb17 | 57 | This means a system crash can corrupt the database or lose the last transactions if buffers are not yet flushed to disk. |
| cbc0d0cf | 58 | * ``nometasync``: flush system buffers to disk only once per transaction, omit the metadata flush. This maintains database integrity, but can potentially lose the last committed transaction if the operating system crashes. |
| 7055fa20 | 59 | * ``mapasync``: (default). Use asynchronous flushes to disk. As with nosync, a system crash can then corrupt the database or lose the last transactions. |
| c7a0a153 NC |
60 | |
| 61 | ||
| 62 | LMDB Structure | |
| 63 | -------------- | |
| 64 | ||
| 6737cb17 NC |
65 | PowerDNS will create the database structure, no need to manually create the database schema. |
| 66 | Also, it is not possible to directly query the LMDB DB, so recommendation is to use either the API, or pdnsutil. |