Stack Overflow
Stack Overflow

Questions tagged [leveldb]

LevelDB is a fast key-value storage library written at Google that provides an ordered mapping from string keys to string values.

LevelDB is a fast key-value storage library written by Google, providing an ordered mapping from string keys to string values.

Inspired by Bigtable, LevelDB is used by many other systems, including Chrome (for IndexDB), Riak (optional back-end), and Bitcoin (blockchain metadata).

Some features

  • Batching writes
  • Forward & backward iteration
  • Compression of the data via Google's Snappy compression library.
  • Data sorted by key; a custom comparison function to override the sort order.
  • Users can create a transient snapshot to get a consistent view of data.

Official Links:

Books

  • Getting Started with LevelDB, By: Andy Dent, Ebook ISBN:978-1-78328-102-2 | ISBN 10:1-78328-102-2
405 questions
9
votes
2 answers

Has LevelDB a max-length limit for keys?

Has LevelDB keys a limit for the key length? I want to save data with url's as key. so this urls can be very very long i.g.…
tiefenb
  • 732
  • 3
  • 16
  • 32
8
votes
3 answers

Double precision floating-point comparison

I'm a little confused here- would comparison of doubles still work correctly when they're stored as opaque (binary) fields? The problem I'm facing is the fact that the double includes a leading bit for the sign (i.e. positive or negative) and when…
Kiril
  • 39,672
  • 31
  • 167
  • 226
8
votes
2 answers

KahaDB and LevelDB - What's the real difference?

I'm trying to use ActiveMQ 5.8.0 in my project. There are two different storage configurations, KahaDB and LevelDB. Depending on the problem, Kaha can be faster than Level or Level can be faster than Kaha. What's the real difference between them?
R. Karlus
  • 2,094
  • 3
  • 24
  • 48
7
votes
2 answers

LevelDB vs. std::map

In our application we use std::map to store (key, value) data and use serialization to store that data on disk. With this approach we are finding that the disk I/O is performance bottleneck and finding values using key is not very fast. I have come…
polapts
  • 5,493
  • 10
  • 37
  • 49
7
votes
0 answers

Problems with newest Firebase Update (iOS, CocoaPods)

I updated Firebase through pod update to Version: 4.8.0 XCode Version: 9.1 Language: Objective-C Since that only weird things are happening in my Xcode: "Lexical or Preprocessor Issue" - I get a 'string' file not found , slice.h and "Parse Issue" -…
Besfort Abazi
  • 373
  • 3
  • 18
7
votes
1 answer

Convert data to leveldb for caffe

I have a bunch of 2D data matrices in Matlab (no image data, but some single precision data). Does anyone know how to convert 2D matlab matrices to the leveldb format which is required by caffe to train a custom neural network? I already did the…
mcExchange
  • 6,154
  • 12
  • 57
  • 103
7
votes
2 answers

How to make a multi-thread application with Node.js, accessing a LevelDB?

There is this in LevelUP Documentation (https://github.com/rvagg/node-levelup#multi-process-access): LevelDB is thread-safe but is not suitable for accessing with multiple processes. You should only ever have a LevelDB database open from a single…
Leonardo
  • 358
  • 2
  • 17
7
votes
3 answers

Does LevelDB supports hot backups (or equivalent)?

Currently we are evaluating several key+value data stores, to replace an older isam currently in use by owr main application (for 20 something years!) ... The problem is that our current isam doesn't support crash recoveries. So LevelDB seemd Ok to…
artejera
  • 1,346
  • 1
  • 11
  • 19
6
votes
2 answers

Can LevelDB snapshots survive a close of the database?

I'm wondering if the 'snapshot' facility of the LevelDB library can create a snapshot reference that could be saved even after a close of the open database object (and thus reused on a subsequent open). I suspect not, which leads to a followup: is…
gojomo
  • 52,260
  • 14
  • 86
  • 115
6
votes
4 answers

Can integer keys / values be stored in LevelDB?

I have searched for key value stores that support integer keys and integer values. LevelDB seems a good option, though I can't find any information on whether integer values/keys are supported
Rosh Cherian
  • 61
  • 1
  • 2
6
votes
1 answer

Performance issue in Golang's key-value store (Badger DB)

In badgerDB, we have billions of keys of type string and values of type HashValueList. In our use case length of HashValueList might be in millions. We have to encode key and value in []byte before inserting into BadgerDb; we are using the…
Vishal Jangid
  • 358
  • 1
  • 10
6
votes
1 answer

Reverse Indexing and Data modeling in Key-Value store

I am new to key-value stores. My objective is to use an embedded key-value store to keep the persistent data model. The data model comprises of few related tables if designed with conventional RDBMS. I was checking a medium article on modeling a…
Neel Basu
  • 12,638
  • 12
  • 82
  • 146
6
votes
2 answers

What is the effect of number of levels in levelled compaction?

I know how levelled compaction works in DBS like Cassandra, rocksdb etc. Some have max number of levels 4 and some have 7. How does this number affect compaction process? Why can't I have just 2 levels, 1st one which has flushed mem-table data…
Bishnu
  • 383
  • 4
  • 14
6
votes
0 answers

Could not build Objective-C Module 'CoreFoundation'

I am having trouble with this issue after updating Firebase through CocoaPods. Any help is greatly appreciated. Any Firebase Version beyond 4.0.2 causes the same error in Xcode (version 10.1). The error: Swift Compiler Error 'string' file not…
Besfort Abazi
  • 373
  • 3
  • 18
6
votes
2 answers

How to avoid blocking of queue browsing after ActiveMQ checkpoint call

There's a problem when Using ActiveMQ with a large number of Persistence Queues (250) á 1000 persistent TextMessages á 10 KB. A scenario requires these messages to remain in the storage over a long time (days), until they are consumed (large amounts…
jforge
  • 176
  • 1
  • 8
1
2
3
…
26 27