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NuDB | fast key/value insert | Key Value Database library

 by   CPPAlliance C++ Version: Current License: BSL-1.0

 by   CPPAlliance C++ Version: Current License: BSL-1.0

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kandi X-RAY | NuDB Summary

NuDB is a C++ library typically used in Database, Key Value Database applications. NuDB has no bugs, it has no vulnerabilities, it has a Permissive License and it has low support. You can download it from GitHub.
NuDB is an append-only, key/value store specifically optimized for random read performance on modern SSDs or equivalent high-IOPS devices. The most common application for NuDB is content addressable storage where a cryptographic digest of the data is used as the key. The read performance and memory usage are independent of the size of the database. These are some other features:.
Support
Support
Quality
Quality
Security
Security
License
License
Reuse
Reuse

kandi-support Support

  • NuDB has a low active ecosystem.
  • It has 334 star(s) with 46 fork(s). There are 30 watchers for this library.
  • It had no major release in the last 12 months.
  • There are 28 open issues and 23 have been closed. On average issues are closed in 36 days. There are 2 open pull requests and 0 closed requests.
  • It has a neutral sentiment in the developer community.
  • The latest version of NuDB is current.
NuDB Support
Best in #Key Value Database
Average in #Key Value Database
NuDB Support
Best in #Key Value Database
Average in #Key Value Database

quality kandi Quality

  • NuDB has no bugs reported.
NuDB Quality
Best in #Key Value Database
Average in #Key Value Database
NuDB Quality
Best in #Key Value Database
Average in #Key Value Database

securitySecurity

  • NuDB has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
NuDB Security
Best in #Key Value Database
Average in #Key Value Database
NuDB Security
Best in #Key Value Database
Average in #Key Value Database

license License

  • NuDB is licensed under the BSL-1.0 License. This license is Permissive.
  • Permissive licenses have the least restrictions, and you can use them in most projects.
NuDB License
Best in #Key Value Database
Average in #Key Value Database
NuDB License
Best in #Key Value Database
Average in #Key Value Database

buildReuse

  • NuDB releases are not available. You will need to build from source code and install.
  • Installation instructions are not available. Examples and code snippets are available.
NuDB Reuse
Best in #Key Value Database
Average in #Key Value Database
NuDB Reuse
Best in #Key Value Database
Average in #Key Value Database
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NuDB Key Features

Low memory footprint

Database size up to 281TB

All keys are the same size

Append-only, no update or delete

Value sizes from 1 to 2^32 bytes (4GB)

Performance independent of growth

Optimized for concurrent fetch

Key file can be rebuilt if needed

Inserts are atomic and consistent

Data file may be efficiently iterated

Key and data files may be on different devices

Hardened against algorithmic complexity attacks

Header-only, no separate library to build

Example

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#include <nudb/nudb.hpp>
#include <cstddef>
#include <cstdint>

int main()
{
    using namespace nudb;
    std::size_t constexpr N = 1000;
    using key_type = std::uint32_t;
    error_code ec;
    auto const dat_path = "db.dat";
    auto const key_path = "db.key";
    auto const log_path = "db.log";
    create<xxhasher>(
        dat_path, key_path, log_path,
        1,
        make_salt(),
        sizeof(key_type),
        block_size("."),
        0.5f,
        ec);
    store db;
    db.open(dat_path, key_path, log_path, ec);
    char data = 0;
    // Insert
    for(key_type i = 0; i < N; ++i)
        db.insert(&i, &data, sizeof(data), ec);
    // Fetch
    for(key_type i = 0; i < N; ++i)
        db.fetch(&i,
            [&](void const* buffer, std::size_t size)
        {
            // do something with buffer, size
        }, ec);
    db.close(ec);
    erase_file(dat_path);
    erase_file(key_path);
    erase_file(log_path);
}

Building

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#include <nudb/nudb.hpp>

Formats

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char[8]         Type            The characters "nudb.key"
uint16          Version         Holds the version number
uint64          UID             Unique ID generated on creation
uint64          Appnum          Application defined constant
uint16          KeySize         Key size in bytes

uint64          Salt            A random seed
uint64          Pepper          The salt hashed
uint16          BlockSize       Size of a file block in bytes

uint16          LoadFactor      Target fraction in 65536ths

uint8[56]       Reserved        Zeroes
uint8[]         Reserved        Zero-pad to block size

Data File

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char[8]             Type            The characters "nudb.dat"
uint16              Version         Holds the version number
uint64              UID             Unique ID generated on creation
uint64              Appnum          Application defined constant
uint16              KeySize         Key size in bytes
uint8[64]           (reserved)      Zeroes

return list of Xelement names

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xmlDoc.Descendants()
      .Where(e => e.Name.LocalName.Contains("Manual"))
      .Select(e => e.Name.LocalName)
      .OrderBy(e => e)
      .ToList();
xmlDoc.Elements("ControlSettings")
      .Descendants()
      .Select(e => e.Name.LocalName)
      .OrderBy(e => e)
      .ToList();
xmlDoc.Descendants()
      .Where(e => e.Name.LocalName.Contains("Manual"))
      .Select(e => e.Name.LocalName)
      .OrderBy(e => e)
      .ToList();
xmlDoc.Elements("ControlSettings")
      .Descendants()
      .Select(e => e.Name.LocalName)
      .OrderBy(e => e)
      .ToList();

Community Discussions

Trending Discussions on NuDB
  • return list of Xelement names
Trending Discussions on NuDB

QUESTION

return list of Xelement names

Asked 2017-Jun-12 at 09:50

I got an XDocument structure as below :

<?xml version="1.0" encoding="utf-8"?>
<body>
 <ControlSettings>
  <Manual-B nudA="20" nudB="3" nud=D"4"  />
  <Manual-A nudA="2" nudB="33" nudD="4"  />
  <Manual-C nudA="20" nudB="20" nudD="40" />
  <another value="true"  />
 </ControlSettings>
 <Score>
  <Manual-F result="fail" />
 </Score>
</body>

I am trying yo get out a sorted list of only the names in controlsettings So that string list should contain :

  • another
  • Manual-A
  • Manual-B
  • Manual-C

How to do that with Xdocuments using xpath / linq ? I tried below but it doesnt seam to work

IEnumerable <string> names =  doc.XPathSelectElements
("..//body//ControlSettings").Select(e => e.Name.LocalName);
   /* other things i tried:
   List<string>mnames = doc.Root.Element("..//controlsettings").
   var query = from x in doc.Descendants("//body//ControlSettings")
    */
 foreach (string localname in names)Console.WriteLine(localname);

ANSWER

Answered 2017-Jun-12 at 09:50

You can get all nodes within a document using Descendants

xmlDoc.Descendants()
      .Where(e => e.Name.LocalName.Contains("Manual"))
      .Select(e => e.Name.LocalName)
      .OrderBy(e => e)
      .ToList();

Or if that's to broad, and you want to be specific to the ControlSettings group, you can dig down like below

xmlDoc.Elements("ControlSettings")
      .Descendants()
      .Select(e => e.Name.LocalName)
      .OrderBy(e => e)
      .ToList();

Source https://stackoverflow.com/questions/44494976

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install NuDB

You can download it from GitHub.

Support

Please report issues or questions here: https://github.com/vinniefalco/NuDB/issues.

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