Jiro Nishiguchi > RocksDB-0.02 > RocksDB

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Module Version: 0.02   Source  

NAME ^

RocksDB - Perl extension for RocksDB

SYNOPSIS ^

  use RocksDB;

  my $db = RocksDB->new('/path/to/db', { create_if_missing => 1 });
  # put, get and delete
  $db->put(foo => 'bar');
  my $val = $db->get('foo');
  $db->delete('foo');

  # batch
  $db->update(sub {
      my $batch = shift; # RocksDB::WriteBatch object
      $batch->put(foo => 'bar');
      $batch->delete('bar');
  });
  # or manually
  my $batch = RocksDB::WriteBatch->new;
  $batch->put(foo => 'bar');
  $batch->delete('bar');
  $db->write($batch);

  # iteration
  my $iter = $db->new_iterator->seek_to_first;
  while (my ($key, $value) = $iter->each) {
      printf "%s: %s\n", $key, $value;
  }

  # in reverse order
  $iter->seek_to_last;
  while (my ($key, $value) = $iter->reverse_each) {
      printf "%s: %s\n", $key, $value;
  }

  # The tie interface
  tie my %db, 'RocksDB', '/path/to/db', { create_if_missing => 1 };

DESCRIPTION ^

RocksDB is a Perl extension for RocksDB.

RocksDB is an embeddable persistent key-value store for fast storage.

See http://rocksdb.org/ for more details.

CONSTRUCTOR ^

RocksDB->new($name :Str[, $options :HashRef]) :RocksDB

Open the database with the specified $name and returns a new RocksDB object.

RocksDB->open($name :Str[, $options :HashRef]) :RocksDB

Alias for new.

METHODS ^

$db->get($key :Str[, $read_options :HashRef]) :Maybe[Str]

If the database contains an entry for $key returns the corresponding value. If there is no entry for $key returns undef.

$db->get_multi(@keys :(Str) [, $read_options :HashRef]) :HashRef

Retrieve several values associated with @keys. @keys should be an array of scalars.

Returns reference to hash, where $href->{$key} holds corresponding value.

$db->put($key :Str, $value :Str[, $write_options :HashRef]) :Undef

Set the database entry for $key to $value.

$db->delete($key :Str[, $write_options :HashRef]) :Undef

Remove the database entry (if any) for $key.

$db->remove($key :Str[, $write_options :HashRef]) :Undef

Alias for remove.

$db->exists($key :Str) :Bool

Return true if the $key is present, false otherwise.

$db->key_may_exist($key :Str[, $value_ref :ScalarRef, $read_options :HashRef]) :Bool

If the key definitely does not exist in the database, then this method returns false, else true. If the caller wants to obtain value when the key is found in memory, a ScalarRef for $value_ref must be passed. This check is potentially lighter-weight than invoking $db->get(). One way to make this lighter weight is to avoid doing any IOs. Default implementation here returns true and not set $value.

$db->merge($key :Str, $value :Str[, $write_options :HashRef]) :Undef

Merge the database entry for $key with $value. The semantics of this operation is determined by the user provided merge_operator when opening DB.

$db->write($batch :RocksDB::WriteBatch[, $write_options :HashRef]) :Undef

Apply the specified updates to the database.

$db->update($callback :CodeRef[, $write_options :HashRef]) :Undef

Call $db->write by callback style.

  $db->update(sub {
      my $batch = shift;
  }); # apply $batch

$db->new_iterator([$read_options :HashRef]) :RocksDB::Iterator

Return a RocksDB::Iterator over the contents of the database. The result of $db->new_iterator() is initially invalid (caller must call one of the seek methods on the iterator before using it).

$db->get_snapshot() :RocksDB::Snapshot

Return a handle to the current DB state. Iterators created with this handle will all observe a stable snapshot of the current DB state.

$db->get_approximate_size($from :Str, $to :Str) :Int

Return the approximate file system space used by keys in "$from .. $to".

Note that the returned sizes measure file system space usage, so if the user data compresses by a factor of ten, the returned sizes will be one-tenth the size of the corresponding user data size.

The results may not include the sizes of recently written data.

$db->get_property($property :Str) :Str

DB implementations can export properties about their state via this method. If $property is a valid property understood by this DB implementation, returns its current value. Otherwise returns undef.

Valid property names include:

  "rocksdb.num-files-at-level<N>" - return the number of files at level <N>,
     where <N> is an ASCII representation of a level number (e.g. "0").
  "rocksdb.stats" - returns a multi-line string that describes statistics
     about the internal operation of the DB.
  "rocksdb.sstables" - returns a multi-line string that describes all
     of the sstables that make up the db contents.

$db->compact_range($begin :Maybe[Str], $end :Maybe[Str] [, $compact_options :HashRef]) :Undef

Compact the underlying storage for the key range [begin,end]. In particular, deleted and overwritten versions are discarded, and the data is rearranged to reduce the cost of operations needed to access the data. This operation should typically only be invoked by users who understand the underlying implementation.

begin == undef is treated as a key before all keys in the database. end == undef is treated as a key after all keys in the database. Therefore the following call will compact the entire database:

   $db->compact_range;

$compact_options might be:

reduce_level :Bool

Defaults to true.

target_level :Int

Defaults to -1.

$db->number_levels() :Int

Number of levels used for this DB.

$db->max_mem_compaction_level() :Int

Maximum level to which a new compacted memtable is pushed if it does not create overlap.

$db->level0_stop_write_trigger() :Int

Number of files in level-0 that would stop writes.

$db->get_name() :Str

Get DB name -- the exact same name that was provided as an argument to RocksDB->new()

$db->flush([$flush_options :HashRef]) :Undef

Flush all mem-table data.

$db->disable_file_deletions() :Undef

Prevent file deletions. Compactions will continue to occur, but no obsolete files will be deleted. Calling this multiple times have the same effect as calling it once.

$db->enable_file_deletions() :Undef

Allow compactions to delete obselete files.

$db->get_sorted_wal_files() :(HashRef, ...)

Retrieve the sorted list of all wal files with earliest file first.

  (
    {
      # log file's pathname relative to the main db dir
      'path_name' => '/000003.log',
      # Primary identifier for log file.
      # This is directly proportional to creation time of the log file
      'log_number' => 157,
      # Log file can be either alive or archived
      'type' => 'alive', # or 'archived'
      # Starting sequence number of writebatch written in this log file
      'start_sequence' => 85,
      # Size of log file on disk in Bytes
      'size_file_bytes' => 28,
    },
    ...
  )

$db->get_latest_sequence_number() :Int

The sequence number of the most recent transaction.

$db->get_updates_since($seq_number :Int) :RocksDB::TransactionLogIterator

Sets iter to an iterator that is positioned at a write-batch containing seq_number. If the sequence number is non existent, it returns an iterator at the first available seq_no after the requested seq_no. Must set WAL_ttl_seconds or WAL_size_limit_MB to large values to use this api, else the WAL files will get cleared aggressively and the iterator might keep getting invalid before an update is read.

$db->delete_file($name :Str) :Undef

Delete the file name from the db directory and update the internal state to reflect that. Supports deletion of sst and log files only. 'name' must be path relative to the db directory. eg. 000001.sst, /archive/000003.log

$db->get_live_files_meta_data() :(HashRef, ...)

Returns a list of all table files with their level, start key and end key.

  (
    {
      # Name of the file
      'name' => '/000140.sst',
      # Level at which this file resides.
      'level' => 1
      # File size in bytes.
      'size' => 339,
      # Smallest user defined key in the file.
      'smallestkey' => 'bar',
      # Largest user defined key in the file.
      'largestkey' => 'foo',
      # smallest seqno in file
      'smallest_seqno' => '0',
      # largest seqno in file
      'largest_seqno' => '0',
    },
    ...
  )

$db->get_statistics() :RocksDB::Statistics

Returns a RocksDB::Statistics object.

It's necessary to specify the 'enable_statistics' option when openning the DB.

$db->get_db_identity() :Str

Returns the globally unique ID created at database creation time.

RocksDB->destroy_db($name :Str) :Undef

Destroy the contents of the specified database. Be very careful using this method.

RocksDB->repair_db($name :Str) :Undef

If a DB cannot be opened, you may attempt to call this method to resurrect as much of the contents of the database as possible. Some data may be lost, so be careful when calling this function on a database that contains important information.

RocksDB->major_version() :Int

Returns the major version of rocksdb.

RocksDB->minor_version() :Int

Returns the minor version of rocksdb.

OPTIONS ^

The following options are supported.

For details, see the documentation for RocksDB itself.

Open options

read_only :Bool

Defaults to false. If true, call rocksdb::DB::OpenForReadOnly().

comparator :RocksDB::Comparator

Defaults to undef. See RocksDB::Comparator.

merge_operator :RocksDB::MergeOperator

Defaults to undef. See RocksDB::MergeOperator, RocksDB::AssociativeMergeOperator.

compaction_filter :RocksDB::CompactionFilter

Defaults to undef. See RocksDB::CompactionFilter.

create_if_missing :Bool

Defaults to false.

error_if_exists :Bool

Defaults to false.

paranoid_checks :Bool

Defaults to false.

write_buffer_size :Int

Defaults to 4MB.

max_write_buffer_number :Int

Defaults to 2.

min_write_buffer_number_to_merge :Int

Defaults to 1.

max_open_files :Int

Defaults to 1000.

block_cache :RocksDB::Cache

Defaults to undef. See RocksDB::Cache, RocksDB::LRUCache.

block_cache_compressed :RocksDB::Cache

Defaults to undef. See RocksDB::Cache, RocksDB::LRUCache.

block_size :Int

Defaults to 4K.

block_restart_interval :Int

Defaults to 16.

compression :Str

Defaults to 'snappy'. It can be specified using the following arguments.

  snappy
  zlib
  bzip2
  none
compression_per_level :ArrayRef[Str]
  ['snappy', 'zlib', 'zlib', 'bzip2', ...]
filter_policy :RocksDB::FilterPolicy

Defaults to undef. See RocksDB::FilterPolicy, RocksDB::BloomFilterPolicy.

prefix_extractor :RocksDB::SliceTransform

Defaults to undef. See RocksDB::SliceTransform, RocksDB::FixedPrefixTransform.

whole_key_filtering :Bool

Defaults to true.

num_levels :Int

Defaults to 7.

level0_file_num_compaction_trigger :Int

Defaults to 4.

level0_slowdown_writes_trigger :Int

Defaults to 8.

level0_stop_writes_trigger :Int

Defaults to 12.

max_mem_compaction_level :Int

Defaults to 2.

target_file_size_base :Int

Defaults to 2MB.

target_file_size_multiplier :Int

Defaults to 1.

max_bytes_for_level_base :Int

Defaults to 10MB.

max_bytes_for_level_multiplier :Int

Defaults to 10.

max_bytes_for_level_multiplier_additional :ArrayRef[Int]

Defaults to 1.

expanded_compaction_factor :Int

Defaults to 25.

source_compaction_factor :Int

Defaults to 1.

max_grandparent_overlap_factor :Int

Defaults to 10.

enable_statistics :Bool

Defaults to false. See RocksDB::Statistics.

disableDataSync :Bool

Defaults to false.

use_fsync :Bool

Defaults to false.

db_stats_log_interval :Int

Defaults to 1800 (half an hour).

db_log_dir :Str

Defaults to "".

wal_dir :Str

Defaults to "".

disable_seek_compaction :Bool

Defaults to false.

delete_obsolete_files_period_micros :Int

Defaults to 21600000000 (6 hours).

max_background_compactions :Int

Defaults to 1.

max_background_flushes :Int

Defaults to 0.

max_log_file_size :Int

Defaults to 0.

log_file_time_to_roll :Int

Defaults to 0 (disabled).

keep_log_file_num :Int

Defaults to 1000.

soft_rate_limit :Num

Defaults to 0 (disabled).

hard_rate_limit :Num

Defaults to 0 (disabled).

rate_limit_delay_max_milliseconds :Int

Defaults to 1000.

max_manifest_file_size :Int

Defaults to MAX_INT.

no_block_cache :Bool

Defaults to false.

table_cache_numshardbits :Int

Defaults to 4.

table_cache_remove_scan_count_limit :Int

Defaults to 16.

arena_block_size :Int

Defaults to 0.

disable_auto_compactions :Bool

Defaults to false.

WAL_ttl_seconds :Int

Defaults to 0.

WAL_size_limit_MB :Int

Defaults to 0.

manifest_preallocation_size :Int

Defaults to 4MB.

purge_redundant_kvs_while_flush :Bool

Defaults to true.

allow_os_buffer :Bool

Defaults to true.

allow_mmap_reads :Bool

Defaults to false.

allow_mmap_writes :Bool

Defaults to true.

is_fd_close_on_exec :Bool

Defaults to true.

skip_log_error_on_recovery :Bool

Defaults to false.

stats_dump_period_sec :Int

Defaults to 3600 (1 hour).

block_size_deviation :Int

Defaults to 10.

advise_random_on_open :Bool

Defaults to true.

access_hint_on_compaction_start :Str

Defaults to 'normal'. It can be specified using the following arguments.

  normal
  none
  sequential
  willneed
use_adaptive_mutex :Bool

Defaults to false.

bytes_per_sync :Int

Defaults to 0.

compaction_style :Str

Defaults to 'level'. It can be specified using the following arguments.

  level
  universal
compaction_options_universal :HashRef

See 'Universal compaction options' section below.

filter_deletes :Bool

Defaults to false.

max_sequential_skip_in_iterations :Int

Defaults to 8.

inplace_update_support :Bool

Defaults to false.

inplace_update_num_locks :Int

Defaults to 10000, if inplace_update_support = true, else 0.

Universal compaction options

size_ratio :Int

Defaults to 1.

min_merge_width :Int

Defaults to 2.

max_merge_width :Int

Defaults to UINT_MAX.

max_size_amplification_percent :Int

Defaults to 200.

compression_size_percent :Int

Defaults to -1.

stop_style :Str

Defaults to 'total_size'. It can be specified using the following arguments.

  total_size
  similar_size

Read options

verify_checksums :Bool

Defaults to false.

fill_cache :Bool

Defaults to true.

prefix_seek :Bool

Defaults to false.

snapshot :RocksDB::Snapshot

Defaults to undef. See RocksDB::Snapshot.

prefix :Str

Defaults to undef.

read_tier :Str

Defaults to 'read_all'. It can be specified using the following arguments.

  read_all
  block_cache

Write options

sync :Bool

Defaults to false.

disableWAL :Bool

Defaults to false.

Flush options

wait :Bool

Defaults to true.

SEE ALSO ^

http://rocksdb.org/

AUTHOR ^

Jiro Nishiguchi <jiro@cpan.org>

COPYRIGHT AND LICENSE ^

 Copyright (c) 2013, Jiro Nishiguchi All rights reserved.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are
 met:
 
    * Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above
 copyright notice, this list of conditions and the following disclaimer
 in the documentation and/or other materials provided with the
 distribution.
    * Neither the name of Jiro Nishiguchi. nor the names of its
 contributors may be used to endorse or promote products derived from
 this software without specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

See also vendor/rocksdb/LICENSE for bundled RocksDB sources.

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