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.

INSTALLATION

This distribution bundles the rocksdb source tree, so you don't need to have rocksdb.

If rocksdb already installed, the installer figures out it.

rocksdb depends on some environment. See vendor/rocksdb/INSTALL.md before installation.

Currently rocksdb supports Linux and OS X only.

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.

`$db->put_multi($key_values :HashRef [, $write_options :HashRef]) :Undef`

Set the database entry for $key_values.

`$db->delete($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

IncreaseParallelism :Undef

Call DBOptions.IncreaseParallelism(). Value will be ignored.

PrepareForBulkLoad :Undef

Call Options.PrepareForBulkLoad(). Value will be ignored.

OptimizeForPointLookup :Int

Call ColumnFamilyOptions.OptimizeForPointLookup() with given value.

OptimizeLevelStyleCompaction :Maybe[Int]

Call ColumnFamilyOptions.OptimizeLevelStyleCompaction() with given value.

OptimizeUniversalStyleCompaction :Maybe[Int]

Call ColumnFamilyOptions.OptimizeUniversalStyleCompaction() with given value.

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.

max_total_wal_size :Int

Defaults to 0.

compression :Str

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

snappy
zlib
bzip2
lz4
lz4hc
none

compression_per_level :ArrayRef[Str]

['snappy', 'zlib', 'zlib', 'bzip2', 'lz4', 'lz4hc' ...]

prefix_extractor :RocksDB::SliceTransform

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

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.

max_compaction_bytes: Int

Defaults to target_file_size_base * 25.

enable_statistics :Bool

Defaults to false. See RocksDB::Statistics.

use_fsync :Bool

Defaults to false.

db_log_dir :Str

Defaults to "".

wal_dir :Str

Defaults to "".

delete_obsolete_files_period_micros :Int

Defaults to 21600000000 (6 hours).

max_background_compactions :Int

Defaults to 1.

max_background_flushes :Int

Defaults to 1.

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.

table_cache_numshardbits :Int

Defaults to 4.

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_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).

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
fifo

compaction_options_universal :HashRef

See 'Universal compaction options' section below.

compaction_options_fifo :HashRef

See 'FIFO compaction options' section below.

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.

memtable_prefix_bloom_size_ratio :Int

Defaults to 0 (disable).

bloom_locality :Int

Defaults to 0.

max_successive_merges :Int

Defaults to 0 (disabled).

block_based_table_options :HashRef

See 'Block-based table options' section below.

plain_table_options :HashRef

See 'Plain table options' section below.

cuckoo_table_options :HashRef

See 'Cuckoo table options' section below.

Block-based table options

cache_index_and_filter_blocks :Bool

Defaults to false.

index_type :Str

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

binary_search
hash_search

hash_index_allow_collision :Bool

Defaults to true.

checksum :Str

Defaults to 'crc32c'. It can be specified using the following arguments.

no_checksum
crc32c
xxhash

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.

filter_policy :RocksDB::FilterPolicy

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

whole_key_filtering :Bool

Defaults to true.

no_block_cache :Bool

Defaults to false.

block_size_deviation :Int

Defaults to 10.

Plain table options

user_key_len :Int

Defaults to 0 (variable length).

bloom_bits_per_key :Int

Defaults to 10.

hash_table_ratio :Num

Defaults to 0.75.

index_sparseness :Int

Defaults to 16.

huge_page_tlb_size :Int

Defaults to 0.

encoding_type :Str

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

plain
prefix

full_scan_mode :Bool

Defaults to false.

store_index_in_file :Bool

Defaults to false.

Cuckoo table options

hash_table_ratio :Num: Defaults to 0.9.
max_search_depth :Int: Defaults to 100.
cuckoo_block_size :Int: Defaults to 5.
identity_as_first_hash :Bool: Defaults to false.
use_module_hash :Bool: Defaults to true.

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

FIFO compaction options

max_table_files_size :Int: Defaults to 1GB.

Read options

verify_checksums :Bool

Defaults to true.

fill_cache :Bool

Defaults to true.

snapshot :RocksDB::Snapshot

Defaults to undef. See RocksDB::Snapshot.

read_tier :Str

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

read_all
block_cache

tailing :Bool

Defaults to false.

total_order_seek :Bool

Defaults to false.

Write options

sync :Bool: Defaults to false.
disableWAL :Bool: Defaults to false.

Flush options

wait :Bool: Defaults to true.

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.

To install RocksDB, copy and paste the appropriate command in to your terminal.

cpanm

cpanm RocksDB

CPAN shell

perl -MCPAN -e shell
install RocksDB

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

SYNOPSIS

DESCRIPTION

INSTALLATION

CONSTRUCTOR

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

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

METHODS

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

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

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

$db->put_multi($key_values :HashRef [, $write_options :HashRef]) :Undef

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

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

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

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

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

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

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

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

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

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

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

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

$db->number_levels() :Int

$db->max_mem_compaction_level() :Int

$db->level0_stop_write_trigger() :Int

$db->get_name() :Str

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

$db->disable_file_deletions() :Undef

$db->enable_file_deletions() :Undef

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

$db->get_latest_sequence_number() :Int

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

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

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

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

$db->get_db_identity() :Str

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

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

RocksDB->major_version() :Int

RocksDB->minor_version() :Int

OPTIONS

Open options

Block-based table options

Plain table options

Cuckoo table options

Universal compaction options

FIFO compaction options

Read options

Write options

Flush options

SEE ALSO

AUTHOR

COPYRIGHT AND LICENSE

Module Install Instructions

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

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

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

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

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

`$db->put_multi($key_values :HashRef [, $write_options :HashRef]) :Undef`

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

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

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

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

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

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

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

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

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

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

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

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

`$db->number_levels() :Int`

`$db->max_mem_compaction_level() :Int`

`$db->level0_stop_write_trigger() :Int`

`$db->get_name() :Str`

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

`$db->disable_file_deletions() :Undef`

`$db->enable_file_deletions() :Undef`

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

`$db->get_latest_sequence_number() :Int`

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

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

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

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

`$db->get_db_identity() :Str`

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

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

`RocksDB->major_version() :Int`

`RocksDB->minor_version() :Int`