Dumps Redis data sets into a format suitable for long-term storage (currently JSON) and loads data from such dump files back into Redis.
- Supports all Redis data types;
- Dumps TTL and expiration times;
- Can load TTL OR original expiration time for expiring keys;
- Can create pretty/human-readable dumps (keys dumped in sorted order, output indented);
- Can stream data when dumping and loading;
- Can be used as a module in a larger program or as a standalone utility;
- Uses an output format compatible with redis-dump.
redis-dump-load may be used as a module and also as a command line tool.
redis-dump-load exports a pickle-like interface, namely
dumps functions. For example:
import redisdl json_text = redisdl.dumps() with open('path/to/dump.json', 'w') as f: # streams data redisdl.dump(f) json_text = '...' redisdl.loads(json_text) with open('path/to/dump.json') as f: # streams data if ijson or jsaone are installed redisdl.load(f)
See the streaming section below for more information about streaming.
Dump and load methods accept options as keyword arguments:
json_text = redisdl.dumps(encoding='iso-8859-1', pretty=True)
The arguments should always be passed in as keywords, i.e, do not rely on the order in which the parameters are currently listed. Options take string values unless otherwise noted. The options are as follows:
host: host name or IP address for redis server
port: port number for redis server
unix_socket_path: connect to redis via a Unix socket instead of TCP/IP; specify the path to the socket
password: specify password to connect to redis
db(integer): redis database to connect to
encoding: encoding to use for encoding or decoding the data, see Unicode section below
pretty(boolean, dump only): produce a pretty-printed JSON which is easier to read; currently this makes
dumpload entire data set into memory rather than stream it
keys(dump only): only dump keys matching specified pattern
use_expireat(boolean, load only): use
expireatin preference to
ttlwhen loading expiring keys
empty(boolean, load only): empty the redis data set before loading the data
streaming_backend(string): streaming backend to use when loading via
loadmethod, if ijson or jsaone is installed and streaming is thus used
Command Line Usage
redisdl.py can be used as a command line tool as follows:
# dump database 0 ./redisdl.py > dump.json ./redisdl.py -o dump.json # load into database 0 ./redisdl.py -l < dump.json ./redisdl.py -l dump.json
redisdl.py can be hard or soft linked as follows:
ln redisdl.py redis-dump ln redisdl.py redis-load
Now it can be used thusly:
# dump database 0 ./redis-dump > dump.json ./redis-dump -o dump.json # load into database 0 ./redis-load < dump.json ./redis-load dump.json
Symlinks work as well. "load" in the executable name triggers the loading
mode, "dump" triggers the dumping mode, otherwise the default is to dump
-l option switches into the loading mode.
All options supported by the module API are accepted when redisdl is invoked as a command line tool. The command line options are:
--help: help text
--host HOST: specify redis host
--port PORT: specify redis port
--socket SOCKET_PATH: connect to Unix socket at the specified path
--password PASSWORD: password to use when connecting to redis
--db DATABASE: redis database to connect to (integer)
--keys PATTERN(dumping only): dump only keys matching specified glob-style pattern
-encoding ENCODING: specify encoding to use
--output PATH: write dump to PATH rather than standard output
--pretty(dumping only): pretty-print JSON
--use-expireat(loading only): use
ttlvalues in the dump
--empty(loading only): empty redis data set before loading
--backend BACKEND(loading only): streaming backend to use
dump will stream data unless
pretty is given and
load will stream data if ijson or jsaone is installed. To determine whether
redis-dump-load supports streaming data load, examine
redisdl.have_streaming_load variable. There are also
redisdl.have_jsaone variables indicating
presence of the respective library.
redis-dump-load prefers ijson over jsaone and does not specify a backend for ijson by default, which as of this writing means that ijson's pure Python backend will be used. To request a specific backend either pass it as follows to the load methods:
... or set the desired backend globally as follows:
redisdl.streaming_backend = 'ijson-yajl2'
The backend argument takes form of "library-library backend", e.g.:
ijson selects the default backend of ijson, which currently is the pure Python one.
ijson-yajl2 selects ijson with yajl2 backend.
yajl2 means the same things as
ijson-yajl2 for compatibility with older redis-dump-load versions.
jsaone selects the jsaone backend.
Note: Streaming loading is substantially slower than lump loading.
To force lump loading of files, read the files in memory and invoke
jsaone support was added in redis-dump-load version 1.0.
TTL, EXPIRE and EXPIREAT
When dumping, redis-dump-load dumps the TTL values for expiring keys
as well as calculated time when the keys will expire (
As Redis does not provide a command to retrieve absolute expiration time of
a key, the expiration time is calculated using the current time on the
client's system. As such, if the time on the client system is not in sync
with time on the system where the Redis server is running,
values will be incorrect.
When loading, redis-dump-load by default uses the TTL values in the dump
ttl key) to set expiration times on the keys in preference to
expireat values. This will maintain the expiration times of the keys
relative to the dump/load time but will change the absolute expiration time
of the keys. Using
--use-expireat command line option or
use_expireat parameter to module functions will make redis-dump-load
expireat values in preference to
ttl values, setting expiring
keys to expire at the same absolute time as they had before they were dumped
(as long as system times are in sync on all machines involved).
Dumping and loading of TTL values and expiration times was added in redis-dump-load version 1.0.
Redis operates on bytes and has no concept of Unicode or encodings. JSON operates on (Unicode) strings and cannot serialize binary data. Therefore, redis-dump-load has to encode Unicode strings into byte strings when loading data into Redis and decode byte strings into Unicode strings when dumping data from Redis. By default redis-dump-load uses utf-8 for encoding data sent to Redis and decoding data received from Redis. This behavior matches redis-py, whose default encoding is utf-8. A different encoding can be specified.
dumps returns strings, that is, instances of
str on Python 2
and instances of
unicode on Python 3.
When dumping to an IO object using
dump, and the IO object accepts
byte strings (such as when a file is opened in binary mode),
.encode() the dumped data using the default
encoding in effect.
ijson's yajl2 backend can only decode
bytes instances, not
When loading data from a file opened in text mode and using ijson-yajl2,
redis-dump-load will encode the file data using utf-8 encoding before
passing the data to ijson. If this fails, try opening the file/stream in
jsaone can only decode text strings (
str instances), not
When loading data from a file opened in binary mode and using jsaone,
redis-dump-load will decode the file data using the default encoding.
If this fails, you can change the default encoding or open the files in text
mode with the encoding appropriately specified in the
redis-dump-load does not lock the entire data set it is dumping, because Redis does not provide a way to do so. As a result, modifications to the data set made while a dump is in progress affect the contents of the dump.
redis-dump-load has a test suite. To run it, install nose and run:
There are several tests that check for race conditions and as such take a long time to run. To skip them, invoke nose thusly:
nosetests -a '!slow'
Released under the 2 clause BSD license.