lev2

lev2

A CLI and a REPL for managing LevelDB instances.

This repo is a fork of lev, originally to make those changes available from NPM

Features

• CLI
  • providing many basic tools to read and write on a leveldb from the command line
  • import / export, and delete by range
• REPL
  • with colorized tab-completion and zsh/fish style key suggestions
  • automatically saves and reloads REPL history

Summary

• Installation
• CLI
  • --get <key>
  • --put <key>
  • --del <key>
  • --batch <operations>
    • Import / Export
    • Bulk delete
  • --keys
  • --values
  • --all
  • --gte <key-pattern>
  • --lte <key-pattern>
  • --prefix <key-pattern>
  • --match <key-pattern>
  • --limit <number>
  • --reverse
  • --count
  • --valueEncoding <string>
  • --location <string>
• --map <JS function string or path>
• REPL
  • GET <key>
  • PUT <key> <value>
  • DEL <key>
  • LS
  • START <key-pattern>
  • END <key-pattern>
  • LIMIT <number>
  • REVERSE

Installation

$ npm install -g lev2

CLI

These all match the parameters used with levelup. The default encoding for the database is set to json.

--get <key>

Get a value

lev --get foo

--put <key>

Put a value

lev --put foo --value bar

--del <key>

Delete a value

lev --del foo

Can be used in combination with --keys, or --all, or implicit --all, to generate a stream of delete operations to be passed to the lev --batch command

lev --keys --del | lev --batch
lev --all --del | lev --batch
lev --gte abc --lte abd --del | lev --batch

--batch <operations>

Put or delete several values, using levelup batch syntax

lev --batch '[
{"type":"del","key":"a"},
{"type":"put","key":"b","value":"123"},
{"type":"put","key":"c","value":"456"}
]'

or from a file

# there should be one entry per line
# either as valid JSON
echo '[
{"type":"del","key":"a"},
{"type":"put","key":"b","value":"123"},
{"type":"put","key":"c","value":"456"}
]' > ops.json
# or as newline-delimited JSON
echo '
{"type":"del","key":"a"}
{"type":"put","key":"b","value":"123"}
{"type":"put","key":"c","value":"456"}
' > ops.json
lev --batch ./operations.json

Import / Export

If the type is omitted, defaults to put, which allows to use the command to do imports/exports, in combination with --all:

# export
lev --all > leveldb.export
# import
lev /tmp/my-new-db --batch leveldb.export

If it's a large export, you can use compress it on the fly

# export
lev --all | gzip -9 > leveldb.export.gz
# import
gzip -d < leveldb.export.gz | lev /tmp/my-new-db --batch

Bulk delete

The --batch option can also be used to delete key/values by range in 2 steps:

# 1 - collect all the key to delete
lev --prefix 'foo' --del > ./deletion_operations
# 2 - pass the file as argument to the --batch option
lev --batch ./deletion_operations

The same can be done with --match

lev --match '*foo*' --del > ./deletion_operations

--keys

List all the keys in the current range

lev --keys

Can be used in combination with --del to generate a stream of delete operations

lev --keys --del | lev --batch

--values

List all the values in the current range. Emit as a new-line delimited stream of json.

lev --values

--all

List all the keys and values in the current range. Emit as a new-line delimited stream of json.

lev --all

It can be used to create an export of the database, to be imported with --batch

lev --all > leveldb.export
lev /tmp/my-new-db --batch leveldb.export

It can be used in combinaision with other options, but can then also be omitted as its the default stream mode

lev --all --prefix 'foo'
# is equivalent to
lev --prefix 'foo'

--gte <key-pattern>

Start the range at keys greater than or equal to <key-pattern>. For strictly greater than, use --gt.

# output all keys and values after 'foo' (implicit --all)
lev --gte 'foo'
# output all keys after 'foo'
lev --keys --gte 'foo'
# the same for values
lev --values --gte 'foo'

For keys and values strictly greater tha

--lte <key-pattern>

End the range at keys lower than or equal to <key-pattern>. For strictly lower than, use --.

# output all keys and values before 'fooz' (implicit --all)
lev --lte 'fooz'
# output all keys before 'fooz'
lev --keys --lte 'fooz'
# the same for values
lev --values --lte 'fooz'
# output all keys between 'foo' and 'fooz'
lev --keys --gte 'foo' --lte 'fooz'
# which is equivalent to

--prefix <key-pattern>

Get all entries for which the key starts by a given prefix

# get all the keys starting by foo
lev --keys --prefix 'foo'
# which is equivalent to
lev --keys --gte 'foo' --lte 'foo\uffff'

--match <key-pattern>

Filter results by a pattern applied on the keys

lev  --keys --match 'f*'
lev  --values --match 'f*'
lev  --all --match 'f*'
# Equivalent to
lev --match 'f*'

See minimatch doc for patterns

--limit <number>

Limit the number of records emitted in the current range.

lev --keys --limit 10
lev --values --prefix 'foo' --limit 100
lev --match 'f*' --limit 10

--reverse

Reverse the stream.

lev --keys --reverse
lev --keys --prefix 'foo' --limit 100 --reverse

--count

Output the count of results in the selected range

# Count all the key/value pairs in the database
lev --count
# Counts the keys and values between 'foo' and 'fooz'
lev --prefix 'foo' --count

--valueEncoding <string>

Specify the encoding for the values (Defaults to 'json').

lev --values --valueEncoding buffer

--location <string>

Specify the path to the LevelDB to use. Defaults to the current directory.

lev --location /tmp/test-db --keys
# Equivalent to
lev /tmp/test-db --keys

--map <JS function string or path>

Pass results in a map function

• either inline

lev --keys --map 'key => key.split(":")[1]'
lev --all --map 'data => data.value.replace(data.key, "")'

• or from a JS file that exports a function

# in ./map_fn.js
module.exports = key => key.split(":")[1]

lev --keys --map ./map_fn.js

If the function, returns null or undefined, the result is filtered-out

This can be used to update the whole database:

# Create a map function that returns an object with the key and an updated value
echo 'module.exports = ({ key, value }) => ({
  key,
  value: value.replace('foo', 'bar')
})' > ./update_values.js
# Create an updated export of the database
lev --map ./update_values.js > ./updated_db
# And re-import
lev --batch ./updated_db

REPL

Start the REPL

# in the current directory
$ lev .
# somewhere else
$ lev path/to/db

Use upper or lower case for the following commands.

GET <key>

Get a key from the database.

PUT <key> <value>

Put a value into the database. If you have keyEncoding or valueEncoding set to json, these values will be parsed from strings into json.

DEL <key>

Delete a key from the database.

LS

Get all the keys in the current range.

START <key-pattern>

Defines the start of the current range. You can also use GT or GTE.

END <key-pattern>

Defines the end of the current range. You can also use LT or LTE.

LIMIT <number>

Limit the number of records in the current range (defaults to 5000).

REVERSE

Reverse the records in the current range.