60 lines
2.4 KiB
Markdown
60 lines
2.4 KiB
Markdown
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# FSHTBKVS
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The FSHTBKVS (Filesystem Hash Table Based Key Value Store) was developed
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to be an easy to deploy key value store with fast lookup times even for (very)
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large data sets and without third party dependencies.
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## Usage
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### Basic
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```python
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from FSHTBKVS import FSHTBKVS
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# create/open a kvs
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kvs = FSHTBKVS(
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'/home/fshtbkvs/data', # path where the kvs will be created/is located
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'Test_KVS' # name of the kvs
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)
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kvs.write('this could be a key', 'this could be a value') # adds/updates a value
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kvs.read('this could be a key') # returns the value for a given key
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kvs.delete('this could be a key') # deletes a value
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```
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### Advanced
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```python
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kvs.export_kvs(file='/tmp/kvs_export.fshtbkvs') # exports the whole kvs into a .fshtbkvs file
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kvs.import_kvs(file='/tmp/kvs_export.fshtbkvs') # imports a .fshtbkvs file
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kvs.wipe_kvs() # deletes all entries
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```
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### Miscellaneous
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```python
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kvs.get_entries() # returns the number of entries
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kvs.get_kvs_name() # returns the name of the kvs
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kvs.get_max_depth() # returns the depth of the kvs
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kvs.get_size_of_kvs() # returns the size of the kvs in megabytes (as float)
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kvs.maintain_kvs() # recreates missing/broken .json files and counts all entries
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```
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## Information
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When creating a KVS, the optional parameter 'max_depth' can be used.
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It specifies how many levels of the hash table will be created.
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The default value is 4, which results in 65,536 .json files. This seems to be
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a sweet spot for most (hobby) projects. If you expect a very large amount of data,
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the value should rather be set higher to keep the access times low. Naturally,
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the higher the selected value, the more difficult it is to handle the KVS
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(with regard to the file system).
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| max_depth | # of .json files created |
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|--------------|-------------------------:|
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| 1 | 16 |
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| 2 | 256 |
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| 3 | 4,096 |
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| **4** | **65,536** |
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| 5 | 1,048,576 |
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| 6 | 16,777,216 |
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| 7 | 268,435,456 |
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