Parse Redis dump.rdb files, Analyze Memory, and Export Data to JSON

Parse Redis dump.rdb files, Analyze Memory, and Export Data to JSON

Rdbtools is a parser for Redis' dump.rdb files. The parser generates events similar to an xml sax parser, and is very efficient memory wise.

In addition, rdbtools provides utilities to :

1. Generate a Memory Report of your data across all databases and keys
2. Convert dump files to JSON
3. Compare two dump files using standard diff tools

Rdbtools is written in Python, though there are similar projects in other languages. See FAQs for more information.

Installing rdbtools

Pre-Requisites :

1. python 2.x and pip.
2. redis-py is optional and only needed to run test cases.

To install from PyPI (recommended) :

pip install rdbtools

To install from source :

git clone https://github.com/sripathikrishnan/redis-rdb-tools
cd redis-rdb-tools
sudo python setup.py install

Converting dump files to JSON

Parse the dump file and print the JSON on standard output

rdb --command json /var/redis/6379/dump.rdb

Only process keys that match the regex

rdb --command json --key "user.*" /var/redis/6379/dump.rdb

Only process hashes starting with "a", in database 2

rdb --command json --db 2 --type hash --key "a.*" /var/redis/6379/dump.rdb

Generate Memory Report

Running with the -c memory generates a CSV report with the approximate memory used by that key.

rdb -c memory /var/redis/6379/dump.rdb > memory.csv

The generated CSV has the following columns - Database Number, Data Type, Key, Memory Used in bytes and Encoding. Memory usage includes the key, the value and any other overheads.

Note that the memory usage is approximate. In general, the actual memory used will be slightly higher than what is reported.

You can filter the report on keys or database number or data type.

The memory report should help you detect memory leaks caused by your application logic. It will also help you optimize Redis memory usage.

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Find Memory used by a Single Key

Sometimes you just want to find the memory used by a particular key, and running the entire memory report on the dump file is time consuming.

In such cases, you can use the redis-memory-for-key command

Example :

redis-memory-for-key person:1

redis-memory-for-key -s localhost -p 6379 -a mypassword person:1

Output :

Key             "person:1"
Bytes               111
Type                hash
Encoding            ziplist
Number of Elements      2
Length of Largest Element   8

NOTE :

1. This was added to redis-rdb-tools version 0.1.3
2. This command depends redis-py package

Comparing RDB files

First, use the --command diff option, and pipe the output to standard sort utility

rdb --command diff /var/redis/6379/dump1.rdb | sort > dump1.txt
rdb --command diff /var/redis/6379/dump2.rdb | sort > dump2.txt

Then, run your favourite diff program

kdiff3 dump1.txt dump2.txt

To limit the size of the files, you can filter on keys using the --key=regex option

Emitting Redis Protocol

You can convert RDB file into a stream of redis protocol using the "protocol" command.

rdb --command protocol /var/redis/6379/dump.rdb

*4
34946
HSET

users:123

firstname

Sripathi

You can pipe the output to netcat and re-import a subset of the data. For example, if you want to shard your data into two redis instances, you can use the --key flag to select a subset of data, and then pipe the output to a running redis instance to load that data.

Read Redis Mass Insert for more information on this.

Using the Parser

import sys
from rdbtools import RdbParser, RdbCallback

class MyCallback(RdbCallback) :
    ''' Simple example to show how callback works. 
        See RdbCallback for all available callback methods.
        See JsonCallback for a concrete example
    ''' 
    def set(self, key, value, expiry):
        print('%s = %s' % (str(key), str(value)))

    def hset(self, key, field, value):
        print('%s.%s = %s' % (str(key), str(field), str(value)))

    def sadd(self, key, member):
        print('%s has {%s}' % (str(key), str(member)))

    def rpush(self, key, value) :
        print('%s has [%s]' % (str(key), str(value)))

    def zadd(self, key, score, member):
        print('%s has {%s : %s}' % (str(key), str(member), str(score)))

callback = MyCallback()
parser = RdbParser(callback)
parser.parse('/var/redis/6379/dump.rdb')

Other Pages

1. Frequently Asked Questions
2. Redis Dump File Specification
3. Redis Dump File Version History - this also has notes on converting a dump file to an older version.

[출처] https://github.com/sripathikrishnan/redis-rdb-tools