# Module rocksdb # * [Description](#description) * [Data Types](#types) * [Function Index](#index) * [Function Details](#functions) Erlang Wrapper for RocksDB. ## Data Types ## ### access_hint() ###


access_hint() = normal | sequential | willneed | none

### backup_engine() ### __abstract datatype__: `backup_engine()` ### backup_info() ###


backup_info() = #{id => non_neg_integer(), timestamp => non_neg_integer(), size => non_neg_integer(), number_files => non_neg_integer()}

### batch_handle() ### __abstract datatype__: `batch_handle()` ### block_based_table_options() ###


block_based_table_options() = [{no_block_cache, boolean()} | {block_size, pos_integer()} | {block_cache, cache_handle()} | {block_cache_size, pos_integer()} | {bloom_filter_policy, BitsPerKey::pos_integer()} | {format_version, 0 | 1 | 2} | {cache_index_and_filter_blocks, boolean()}]

### cache_handle() ### __abstract datatype__: `cache_handle()` ### cf_handle() ### __abstract datatype__: `cf_handle()` ### cf_options() ###


cf_options() = [{block_cache_size_mb_for_point_lookup, non_neg_integer()} | {memtable_memory_budget, pos_integer()} | {write_buffer_size, pos_integer()} | {max_write_buffer_number, pos_integer()} | {min_write_buffer_number_to_merge, pos_integer()} | {compression, compression_type()} | {num_levels, pos_integer()} | {level0_file_num_compaction_trigger, integer()} | {level0_slowdown_writes_trigger, integer()} | {level0_stop_writes_trigger, integer()} | {max_mem_compaction_level, pos_integer()} | {target_file_size_base, pos_integer()} | {target_file_size_multiplier, pos_integer()} | {max_bytes_for_level_base, pos_integer()} | {max_bytes_for_level_multiplier, pos_integer()} | {max_compaction_bytes, pos_integer()} | {soft_rate_limit, float()} | {hard_rate_limit, float()} | {arena_block_size, integer()} | {disable_auto_compactions, boolean()} | {purge_redundant_kvs_while_flush, boolean()} | {compaction_style, compaction_style()} | {compaction_pri, compaction_pri()} | {filter_deletes, boolean()} | {max_sequential_skip_in_iterations, pos_integer()} | {inplace_update_support, boolean()} | {inplace_update_num_locks, pos_integer()} | {table_factory_block_cache_size, pos_integer()} | {in_memory_mode, boolean()} | {block_based_table_options, block_based_table_options()} | {level_compaction_dynamic_level_bytes, boolean()} | {optimize_filters_for_hits, boolean()} | {prefix_transform, [{fixed_prefix_transform, integer()} | {capped_prefix_transform, integer()}]}]

### compaction_pri() ###


compaction_pri() = compensated_size | oldest_largest_seq_first | oldest_smallest_seq_first

### compaction_style() ###


compaction_style() = level | universal | fifo | none

### compression_type() ###


compression_type() = snappy | zlib | bzip2 | lz4 | lz4h | none

### db_handle() ### __abstract datatype__: `db_handle()` ### db_options() ###


db_options() = [{env, env()} | {total_threads, pos_integer()} | {create_if_missing, boolean()} | {create_missing_column_families, boolean()} | {error_if_exists, boolean()} | {paranoid_checks, boolean()} | {max_open_files, integer()} | {max_total_wal_size, non_neg_integer()} | {use_fsync, boolean()} | {db_paths, [#db_path{path = file:filename_all(), target_size = non_neg_integer()}]} | {db_log_dir, file:filename_all()} | {wal_dir, file:filename_all()} | {delete_obsolete_files_period_micros, pos_integer()} | {max_background_jobs, pos_integer()} | {max_background_compactions, pos_integer()} | {max_background_flushes, pos_integer()} | {max_log_file_size, non_neg_integer()} | {log_file_time_to_roll, non_neg_integer()} | {keep_log_file_num, pos_integer()} | {max_manifest_file_size, pos_integer()} | {table_cache_numshardbits, pos_integer()} | {wal_ttl_seconds, non_neg_integer()} | {wal_size_limit_mb, non_neg_integer()} | {manifest_preallocation_size, pos_integer()} | {allow_mmap_reads, boolean()} | {allow_mmap_writes, boolean()} | {is_fd_close_on_exec, boolean()} | {skip_log_error_on_recovery, boolean()} | {stats_dump_period_sec, non_neg_integer()} | {advise_random_on_open, boolean()} | {access_hint, access_hint()} | {compaction_readahead_size, non_neg_integer()} | {new_table_reader_for_compaction_inputs, boolean()} | {use_adaptive_mutex, boolean()} | {bytes_per_sync, non_neg_integer()} | {skip_stats_update_on_db_open, boolean()} | {wal_recovery_mode, wal_recovery_mode()} | {allow_concurrent_memtable_write, boolean()} | {enable_write_thread_adaptive_yield, boolean()} | {db_write_buffer_size, non_neg_integer()} | {in_memory, boolean()} | {rate_limiter, rate_limiter_handle()} | {max_subcompactions, non_neg_integer()}]

### env() ### __abstract datatype__: `env()` ### env_handle() ### __abstract datatype__: `env_handle()` ### env_priority() ###


env_priority() = priority_high | priority_low

### fold_fun() ###


fold_fun() = fun(({Key::binary(), Value::binary()}, any()) -> any())

### fold_keys_fun() ###


fold_keys_fun() = fun((Key::binary(), any()) -> any())

### iterator_action() ###


iterator_action() = first | last | next | prev | binary() | {seek, binary()} | {seek_for_prev, binary()}

### itr_handle() ### __abstract datatype__: `itr_handle()` ### options() ###


options() = db_options() | cf_options()

### rate_limiter_handle() ### __abstract datatype__: `rate_limiter_handle()` ### read_options() ###


read_options() = [{verify_checksums, boolean()} | {fill_cache, boolean()} | {iterate_upper_bound, binary()} | {tailing, boolean()} | {total_order_seek, boolean()} | {snapshot, snapshot_handle()}]

### snapshot_handle() ### __abstract datatype__: `snapshot_handle()` ### wal_recovery_mode() ###


wal_recovery_mode() = tolerate_corrupted_tail_records | absolute_consistency | point_in_time_recovery | skip_any_corrupted_records

### write_actions() ###


write_actions() = [{put, Key::binary(), Value::binary()} | {put, ColumnFamilyHandle::cf_handle(), Key::binary(), Value::binary()} | {delete, Key::binary()} | {delete, ColumnFamilyHandle::cf_handle(), Key::binary()} | {single_delete, Key::binary()} | {single_delete, ColumnFamilyHandle::cf_handle(), Key::binary()} | clear]

### write_options() ###


write_options() = [{sync, boolean()} | {disable_wal, boolean()} | {ignore_missing_column_families, boolean()}]

## Function Index ##

batch/0	create a new batch in memory.
batch_clear/1	reset the batch, clear all operations.
batch_count/1	return the number of operations in the batch.
batch_data_size/1	Retrieve data size of the batch.
batch_delete/2	batch implementation of delete operation to the batch.
batch_delete/3	like `batch_delete/2` but apply the operation to a column family.
batch_merge/3	add a merge operation to the batch.
batch_merge/4	like `batch_mege/3` but apply the operation to a column family.
batch_put/3	add a put operation to the batch.
batch_put/4	like `batch_put/3` but apply the operation to a column family.
batch_rollback/1	rollback the operations to the latest checkpoint.
batch_savepoint/1	store a checkpoint in the batch to which you can rollback later.
batch_single_delete/2	batch implementation of single_delete operation to the batch.
batch_single_delete/3	like `batch_single_delete/2` but apply the operation to a column family.
batch_tolist/1	return all the operation sin the batch as a list of operations.
checkpoint/2	take a snapshot of a running RocksDB database in a separate directory http://rocksdb.org/blog/2609/use-checkpoints-for-efficient-snapshots/.
close/1	Close RocksDB.
close_backup/1	stop and close the backup note: experimental for testing only.
close_updates_iterator/1	close the transaction log.
count/1	Return the approximate number of keys in the default column family.
count/2	Return the approximate number of keys in the specified column family.
create_column_family/3	Create a new column family.
create_new_backup/2	Captures the state of the database in the latest backup.
default_env/0	return a default db environment.
delete/3	Delete a key/value pair in the default column family.
delete/4	Delete a key/value pair in the specified column family.
delete_backup/2	deletes a specific backup.
delete_range/4	Removes the database entries in the range ["BeginKey", "EndKey"), i.e., including "BeginKey" and excluding "EndKey".
delete_range/5	Removes the database entries in the range ["BeginKey", "EndKey").
destroy/2	Destroy the contents of the specified database.
destroy_column_family/1	Destroy a column family.
destroy_env/1	destroy an environment.
drop_column_family/1	Drop a column family.
flush/1	Flush all mem-table data.
flush/2	Flush all mem-table data.
fold/4	Calls Fun(Elem, AccIn) on successive elements in the default column family starting with AccIn == Acc0.
fold/5	Calls Fun(Elem, AccIn) on successive elements in the specified column family Other specs are same with fold/4.
fold_keys/4	Calls Fun(Elem, AccIn) on successive elements in the default column family starting with AccIn == Acc0.
fold_keys/5	Calls Fun(Elem, AccIn) on successive elements in the specified column family Other specs are same with fold_keys/4.
garbage_collect_backup/1	Will delete all the files we don't need anymore It will do the full scan of the files/ directory and delete all the files that are not referenced.
get/3	Retrieve a key/value pair in the default column family.
get/4	Retrieve a key/value pair in the specified column family.
get_backup_info/1	Returns info about backups in backup_info.
get_capacity/1	returns the maximum configured capacity of the cache.
get_latest_sequence_number/1	get latest sequence from the log.
get_pinned_usage/1	returns the memory size for the entries in use by the system.
get_property/2	Return the RocksDB internal status of the default column family specified at Property.
get_property/3	Return the RocksDB internal status of the specified column family specified at Property.
get_snapshot_sequence/1	returns Snapshot's sequence number.
get_usage/1	returns the memory size for a specific entry in the cache.
is_empty/1	is the database empty.
iterator/2	Return a iterator over the contents of the database.
iterator/3	Return a iterator over the contents of the database.
iterator_close/1	Close a iterator.
iterator_move/2	Move to the specified place.
iterator_refresh/1	Refresh iterator.
iterators/3	Return a iterator over the contents of the specified column family.
list_column_families/2	List column families.
mem_env/0	return a memory environment.
merge/4	Merge a key/value pair into the default column family.
merge/5	Merge a key/value pair into the specified column family.
new_clock_cache/1	Similar to NewLRUCache, but create a cache based on CLOCK algorithm with better concurrent performance in some cases.
new_lru_cache/1	// Create a new cache with a fixed size capacity.
new_rate_limiter/2	create new Limiter.
next_binary_update/1	go to the last update as a binary in the transaction log, can be ussed with the write_binary_update function.
next_update/1	like binary update but also return the batch as a list of operations.
open/2	Open RocksDB with the defalut column family.
open_backup_engine/1	open a new backup engine.
open_with_cf/3	Open RocksDB with the specified column families.
purge_old_backup/2	deletes old backups, keeping latest num_backups_to_keep alive.
put/4	Put a key/value pair into the default column family.
put/5	Put a key/value pair into the specified column family.
release_batch/1
release_cache/1	release the cache.
release_rate_limiter/1	release the limiter.
release_snapshot/1	release a snapshot.
repair/2	Try to repair as much of the contents of the database as possible.
restore_db_from_backup/3	restore from backup with backup_id.
restore_db_from_backup/4	restore from backup with backup_id.
restore_db_from_latest_backup/2	restore from the latest backup.
restore_db_from_latest_backup/3	restore from the latest backup.
set_capacity/2	sets the maximum configured capacity of the cache.
set_db_background_threads/2	set background threads of a database.
set_db_background_threads/3	set database background threads of low and high prioriry threads pool of an environment Flush threads are in the HIGH priority pool, while compaction threads are in the LOW priority pool.
set_env_background_threads/2	set background threads of an environment.
set_env_background_threads/3	set background threads of low and high prioriry threads pool of an environment Flush threads are in the HIGH priority pool, while compaction threads are in the LOW priority pool.
set_strict_capacity_limit/2	sets strict_capacity_limit flag of the cache.
single_delete/3	Remove the database entry for "key".
single_delete/4	like `single_delete/3` but on the specified column family.
snapshot/1	return a database snapshot Snapshots provide consistent read-only views over the entire state of the key-value store.
stats/1	Return the current stats of the default column family Implemented by calling GetProperty with "rocksdb.stats".
stats/2	Return the current stats of the specified column family Implemented by calling GetProperty with "rocksdb.stats".
stop_backup/1
sync_wal/1	Sync the wal.
updates_iterator/2	create a new iterator to retrive ethe transaction log since a sequce.
verify_backup/2	checks that each file exists and that the size of the file matches our expectations.
write/3	Apply the specified updates to the database.
write_batch/3	write the batch to the database.
write_binary_update/3	apply a set of operation coming from a transaction log to another database.

## Function Details ## ### batch/0 ###


batch() -> {ok, Batch::batch_handle()}

create a new batch in memory. A batch is a nif resource attached to the current process. Pay attention when you share it with other processes as it may not been released. To force its release you will need to use the close_batch function. ### batch_clear/1 ###


batch_clear(Batch::batch_handle()) -> ok

reset the batch, clear all operations. ### batch_count/1 ###


batch_count(_Batch::batch_handle()) -> Count::non_neg_integer()

return the number of operations in the batch ### batch_data_size/1 ###


batch_data_size(_Batch::batch_handle()) -> BatchSize::non_neg_integer()

Retrieve data size of the batch. ### batch_delete/2 ###


batch_delete(Batch::batch_handle(), Key::binary()) -> ok

batch implementation of delete operation to the batch ### batch_delete/3 ###


batch_delete(Batch::batch_handle(), ColumnFamily::cf_handle(), Key::binary()) -> ok

like `batch_delete/2` but apply the operation to a column family ### batch_merge/3 ###


batch_merge(Batch::batch_handle(), Key::binary(), Value::binary()) -> ok

add a merge operation to the batch ### batch_merge/4 ###


batch_merge(Batch::batch_handle(), ColumnFamily::cf_handle(), Key::binary(), Value::binary()) -> ok

like `batch_mege/3` but apply the operation to a column family ### batch_put/3 ###


batch_put(Batch::batch_handle(), Key::binary(), Value::binary()) -> ok

add a put operation to the batch ### batch_put/4 ###


batch_put(Batch::batch_handle(), ColumnFamily::cf_handle(), Key::binary(), Value::binary()) -> ok

like `batch_put/3` but apply the operation to a column family ### batch_rollback/1 ###


batch_rollback(Batch::batch_handle()) -> ok

rollback the operations to the latest checkpoint ### batch_savepoint/1 ###


batch_savepoint(Batch::batch_handle()) -> ok

store a checkpoint in the batch to which you can rollback later ### batch_single_delete/2 ###


batch_single_delete(Batch::batch_handle(), Key::binary()) -> ok

batch implementation of single_delete operation to the batch ### batch_single_delete/3 ###


batch_single_delete(Batch::batch_handle(), ColumnFamily::cf_handle(), Key::binary()) -> ok

like `batch_single_delete/2` but apply the operation to a column family ### batch_tolist/1 ###


batch_tolist(Batch::batch_handle()) -> Ops::write_actions()

return all the operation sin the batch as a list of operations ### checkpoint/2 ###


checkpoint(DbHandle::db_handle(), Path::file:filename_all()) -> ok | {error, any()}

take a snapshot of a running RocksDB database in a separate directory http://rocksdb.org/blog/2609/use-checkpoints-for-efficient-snapshots/ ### close/1 ###


close(DBHandle) -> Res

DBHandle = db_handle()
Res = ok | {error, any()}

Close RocksDB ### close_backup/1 ###


close_backup(BackupEngine::backup_engine()) -> ok

stop and close the backup note: experimental for testing only ### close_updates_iterator/1 ### `close_updates_iterator(Iterator) -> any()` close the transaction log ### count/1 ###


count(DBHandle::db_handle()) -> non_neg_integer() | {error, any()}

Return the approximate number of keys in the default column family. Implemented by calling GetIntProperty with "rocksdb.estimate-num-keys" ### count/2 ###


count(DBHandle::db_handle(), CFHandle::cf_handle()) -> non_neg_integer() | {error, any()}

Return the approximate number of keys in the specified column family. ### create_column_family/3 ###


create_column_family(DBHandle, Name, CFOpts) -> Res

DBHandle = db_handle()
Name = string()
CFOpts = cf_options()
Res = {ok, cf_handle()} | {error, any()}

Create a new column family ### create_new_backup/2 ###


create_new_backup(BackupEngine::backup_engine(), Db::db_handle()) -> ok | {error, term()}

Captures the state of the database in the latest backup ### default_env/0 ###


default_env() -> {ok, env_handle()}

return a default db environment ### delete/3 ###


delete(DBHandle, Key, WriteOpts) -> ok | {error, any()}

DBHandle = db_handle()
Key = binary()
WriteOpts = write_options()

Delete a key/value pair in the default column family ### delete/4 ###


delete(DBHandle, CFHandle, Key, WriteOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
Key = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Delete a key/value pair in the specified column family ### delete_backup/2 ###


delete_backup(BackupEngine::backup_engine(), BackupId::non_neg_integer()) -> ok | {error, any()}

deletes a specific backup ### delete_range/4 ###


delete_range(DBHandle, BeginKey, EndKey, WriteOpts) -> Res

DBHandle = db_handle()
BeginKey = binary()
EndKey = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Removes the database entries in the range ["BeginKey", "EndKey"), i.e., including "BeginKey" and excluding "EndKey". Returns OK on success, and a non-OK status on error. It is not an error if no keys exist in the range ["BeginKey", "EndKey"). This feature is currently an experimental performance optimization for deleting very large ranges of contiguous keys. Invoking it many times or on small ranges may severely degrade read performance; in particular, the resulting performance can be worse than calling Delete() for each key in the range. Note also the degraded read performance affects keys outside the deleted ranges, and affects database operations involving scans, like flush and compaction. Consider setting ReadOptions::ignore_range_deletions = true to speed up reads for key(s) that are known to be unaffected by range deletions. ### delete_range/5 ###


delete_range(DBHandle, CFHandle, BeginKey, EndKey, WriteOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
BeginKey = binary()
EndKey = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Removes the database entries in the range ["BeginKey", "EndKey"). like `delete_range/3` but for a column family ### destroy/2 ###


destroy(Name::file:filename_all(), DBOpts::db_options()) -> ok | {error, any()}

Destroy the contents of the specified database. Be very careful using this method. ### destroy_column_family/1 ###


destroy_column_family(CFHandle) -> Res

CFHandle = cf_handle()
Res = ok | {error, any()}

Destroy a column family ### destroy_env/1 ###


destroy_env(Env::env_handle()) -> ok

destroy an environment ### drop_column_family/1 ###


drop_column_family(CFHandle) -> Res

CFHandle = cf_handle()
Res = ok | {error, any()}

Drop a column family ### flush/1 ###


flush(DbHandle::db_handle()) -> ok | {error, term()}

Flush all mem-table data. ### flush/2 ###


flush(DbHandle::db_handle(), CfHandle::cf_handle()) -> ok | {error, term()}

Flush all mem-table data. ### fold/4 ###


fold(DBHandle, Fun, AccIn, ReadOpts) -> AccOut

DBHandle = db_handle()
Fun = fold_fun()
AccIn = any()
ReadOpts = read_options()
AccOut = any()

Calls Fun(Elem, AccIn) on successive elements in the default column family starting with AccIn == Acc0. Fun/2 must return a new accumulator which is passed to the next call. The function returns the final value of the accumulator. Acc0 is returned if the default column family is empty. ### fold/5 ###


fold(DBHandle, CFHandle, Fun, AccIn, ReadOpts) -> AccOut

DBHandle = db_handle()
CFHandle = cf_handle()
Fun = fold_fun()
AccIn = any()
ReadOpts = read_options()
AccOut = any()

Calls Fun(Elem, AccIn) on successive elements in the specified column family Other specs are same with fold/4 ### fold_keys/4 ###


fold_keys(DBHandle, Fun, AccIn, ReadOpts) -> AccOut

DBHandle = db_handle()
Fun = fold_keys_fun()
AccIn = any()
ReadOpts = read_options()
AccOut = any()


fold_keys(DBHandle, CFHandle, Fun, AccIn, ReadOpts) -> AccOut

DBHandle = db_handle()
CFHandle = cf_handle()
Fun = fold_keys_fun()
AccIn = any()
ReadOpts = read_options()
AccOut = any()

Calls Fun(Elem, AccIn) on successive elements in the specified column family Other specs are same with fold_keys/4 ### garbage_collect_backup/1 ###


garbage_collect_backup(BackupEngine::backup_engine()) -> ok

Will delete all the files we don't need anymore It will do the full scan of the files/ directory and delete all the files that are not referenced. ### get/3 ###


get(DBHandle, Key, ReadOpts) -> Res

DBHandle = db_handle()
Key = binary()
ReadOpts = read_options()
Res = {ok, binary()} | not_found | {error, any()}

Retrieve a key/value pair in the default column family ### get/4 ###


get(DBHandle, CFHandle, Key, ReadOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
Key = binary()
ReadOpts = read_options()
Res = {ok, binary()} | not_found | {error, any()}

Retrieve a key/value pair in the specified column family ### get_backup_info/1 ###


get_backup_info(BackupEngine::backup_engine()) -> [backup_info()]

Returns info about backups in backup_info ### get_capacity/1 ###


get_capacity(Cache::cache_handle()) -> non_neg_integer()

returns the maximum configured capacity of the cache. ### get_latest_sequence_number/1 ###


get_latest_sequence_number(Db::db_handle()) -> Seq::non_neg_integer()

get latest sequence from the log ### get_pinned_usage/1 ###


get_pinned_usage(Cache::cache_handle()) -> non_neg_integer()

returns the memory size for the entries in use by the system ### get_property/2 ###


get_property(DBHandle::db_handle(), Property::binary()) -> {ok, any()} | {error, any()}

Return the RocksDB internal status of the default column family specified at Property ### get_property/3 ###


get_property(DBHandle::db_handle(), CFHandle::cf_handle(), Property::binary()) -> string() | {error, any()}

Return the RocksDB internal status of the specified column family specified at Property ### get_snapshot_sequence/1 ###


get_snapshot_sequence(SnapshotHandle::snapshot_handle()) -> Sequence::non_neg_integer()

returns Snapshot's sequence number ### get_usage/1 ###


get_usage(Cache::cache_handle()) -> non_neg_integer()

returns the memory size for a specific entry in the cache. ### is_empty/1 ###


is_empty(DBHandle::db_handle()) -> true | false

is the database empty ### iterator/2 ###


iterator(DBHandle, ReadOpts) -> Res

DBHandle = db_handle()
ReadOpts = read_options()
Res = {ok, itr_handle()} | {error, any()}

Return a iterator over the contents of the database. The result of iterator() is initially invalid (caller must call iterator_move function on the iterator before using it). ### iterator/3 ###


iterator(DBHandle, CFHandle, ReadOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
ReadOpts = read_options()
Res = {ok, itr_handle()} | {error, any()}

Return a iterator over the contents of the database. The result of iterator() is initially invalid (caller must call iterator_move function on the iterator before using it). ### iterator_close/1 ###


iterator_close(ITRHandle) -> ok

ITRHandle = itr_handle()

Close a iterator ### iterator_move/2 ###


iterator_move(ITRHandle, ITRAction) -> {ok, Key::binary(), Value::binary()} | {ok, Key::binary()} | {error, invalid_iterator} | {error, iterator_closed}

ITRHandle = itr_handle()
ITRAction = iterator_action()

Move to the specified place ### iterator_refresh/1 ###


iterator_refresh(ITRHandle) -> ok

ITRHandle = itr_handle()

Refresh iterator ### iterators/3 ###


iterators(DBHandle, CFHandle, ReadOpts) -> {ok, itr_handle()} | {error, any()}

DBHandle = db_handle()
CFHandle = cf_handle()
ReadOpts = read_options()

Return a iterator over the contents of the specified column family. ### list_column_families/2 ###


list_column_families(Name, DBOpts) -> Res

Name = file:filename_all()
DBOpts = db_options()
Res = {ok, [string()]} | {error, any()}

List column families ### mem_env/0 ###


mem_env() -> {ok, env_handle()}

return a memory environment ### merge/4 ###


merge(DBHandle, Key, Value, WriteOpts) -> Res

DBHandle = db_handle()
Key = binary()
Value = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Merge a key/value pair into the default column family ### merge/5 ###


merge(DBHandle, CFHandle, Key, Value, WriteOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
Key = binary()
Value = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Merge a key/value pair into the specified column family ### new_clock_cache/1 ###


new_clock_cache(Capacity::non_neg_integer()) -> {ok, cache_handle()}

Similar to NewLRUCache, but create a cache based on CLOCK algorithm with better concurrent performance in some cases. See util/clock_cache.cc for more detail. ### new_lru_cache/1 ###


new_lru_cache(Capacity::non_neg_integer()) -> {ok, cache_handle()}

// Create a new cache with a fixed size capacity. The cache is sharded to 2^num_shard_bits shards, by hash of the key. The total capacity is divided and evenly assigned to each shard. ### new_rate_limiter/2 ### `new_rate_limiter(RateBytesPerSec, Auto) -> any()` create new Limiter ### next_binary_update/1 ###


next_binary_update(Iterator::term()) -> {ok, LastSeq::non_neg_integer(), BinLog::binary()} | {error, term()}

go to the last update as a binary in the transaction log, can be ussed with the write_binary_update function. ### next_update/1 ###


next_update(Iterator::term()) -> {ok, LastSeq::non_neg_integer(), Log::write_actions(), BinLog::binary()} | {error, term()}

like binary update but also return the batch as a list of operations ### open/2 ###


open(Name, DBOpts) -> Result

Name = file:filename_all()
DBOpts = options()
Result = {ok, db_handle()} | {error, any()}

Open RocksDB with the defalut column family ### open_backup_engine/1 ###


open_backup_engine(Path::string) -> {ok, backup_engine()} | {error, term()}

open a new backup engine ### open_with_cf/3 ###


open_with_cf(Name, DBOpts, CFDescriptors) -> {ok, db_handle(), [cf_handle()]} | {error, any()}

Name = file:filename_all()
DBOpts = db_options()
CFDescriptors = [#cf_descriptor{name = string(), options = cf_options()}]

Open RocksDB with the specified column families ### purge_old_backup/2 ###


purge_old_backup(BackupEngine::backup_engine(), NumBackupToKeep::non_neg_integer()) -> ok | {error, any()}

deletes old backups, keeping latest num_backups_to_keep alive ### put/4 ###


put(DBHandle, Key, Value, WriteOpts) -> Res

DBHandle = db_handle()
Key = binary()
Value = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Put a key/value pair into the default column family ### put/5 ###


put(DBHandle, CFHandle, Key, Value, WriteOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
Key = binary()
Value = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

Put a key/value pair into the specified column family ### release_batch/1 ###


release_batch(Batch::batch_handle()) -> ok

### release_cache/1 ### `release_cache(Cache) -> any()` release the cache ### release_rate_limiter/1 ### `release_rate_limiter(Limiter) -> any()` release the limiter ### release_snapshot/1 ###


release_snapshot(SnapshotHandle::snapshot_handle()) -> ok | {error, any()}

release a snapshot ### repair/2 ###


repair(Name::file:filename_all(), DBOpts::db_options()) -> ok | {error, any()}

Try to repair as much of the contents of the database as possible. Some data may be lost, so be careful when calling this function ### restore_db_from_backup/3 ###


restore_db_from_backup(BackupEngine, BackupId, DbDir) -> Result

BackupEngine = backup_engine()
BackupId = non_neg_integer()
DbDir = string()
Result = ok | {error, any()}

restore from backup with backup_id ### restore_db_from_backup/4 ###


restore_db_from_backup(BackupEngine, BackupId, DbDir, WalDir) -> Result

BackupEngine = backup_engine()
BackupId = non_neg_integer()
DbDir = string()
WalDir = string()
Result = ok | {error, any()}

restore from backup with backup_id ### restore_db_from_latest_backup/2 ###


restore_db_from_latest_backup(BackupEngine, DbDir) -> Result

BackupEngine = backup_engine()
DbDir = string()
Result = ok | {error, any()}

restore from the latest backup ### restore_db_from_latest_backup/3 ###


restore_db_from_latest_backup(BackupEngine, DbDir, WalDir) -> Result

BackupEngine = backup_engine()
DbDir = string()
WalDir = string()
Result = ok | {error, any()}

restore from the latest backup ### set_capacity/2 ###


set_capacity(Cache::cache_handle(), Capacity::non_neg_integer()) -> ok

sets the maximum configured capacity of the cache. When the new capacity is less than the old capacity and the existing usage is greater than new capacity, the implementation will do its best job to purge the released entries from the cache in order to lower the usage ### set_db_background_threads/2 ###


set_db_background_threads(DB::db_handle(), N::non_neg_integer()) -> ok

set background threads of a database ### set_db_background_threads/3 ###


set_db_background_threads(DB::db_handle(), N::non_neg_integer(), Priority::env_priority()) -> ok

set database background threads of low and high prioriry threads pool of an environment Flush threads are in the HIGH priority pool, while compaction threads are in the LOW priority pool. To increase the number of threads in each pool call: ### set_env_background_threads/2 ###


set_env_background_threads(Env::env_handle(), N::non_neg_integer()) -> ok

set background threads of an environment ### set_env_background_threads/3 ###


set_env_background_threads(Env::env_handle(), N::non_neg_integer(), Priority::env_priority()) -> ok

set background threads of low and high prioriry threads pool of an environment Flush threads are in the HIGH priority pool, while compaction threads are in the LOW priority pool. To increase the number of threads in each pool call: ### set_strict_capacity_limit/2 ###


set_strict_capacity_limit(Cache::cache_handle(), StrictCapacityLimit::boolean()) -> ok

sets strict_capacity_limit flag of the cache. If the flag is set to true, insert to cache will fail if no enough capacity can be free. ### single_delete/3 ###


single_delete(DBHandle, Key, WriteOpts) -> ok | {error, any()}

DBHandle = db_handle()
Key = binary()
WriteOpts = write_options()

Remove the database entry for "key". Requires that the key exists and was not overwritten. Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database. If a key is overwritten (by calling Put() multiple times), then the result of calling SingleDelete() on this key is undefined. SingleDelete() only behaves correctly if there has been only one Put() for this key since the previous call to SingleDelete() for this key. This feature is currently an experimental performance optimization for a very specific workload. It is up to the caller to ensure that SingleDelete is only used for a key that is not deleted using Delete() or written using Merge(). Mixing SingleDelete operations with Deletes can result in undefined behavior. Note: consider setting options `{sync, true}`. ### single_delete/4 ###


single_delete(DBHandle, CFHandle, Key, WriteOpts) -> Res

DBHandle = db_handle()
CFHandle = cf_handle()
Key = binary()
WriteOpts = write_options()
Res = ok | {error, any()}

like `single_delete/3` but on the specified column family ### snapshot/1 ###


snapshot(DbHandle::db_handle()) -> {ok, snapshot_handle()} | {error, any()}

return a database snapshot Snapshots provide consistent read-only views over the entire state of the key-value store ### stats/1 ###


stats(DBHandle::db_handle()) -> {ok, any()} | {error, any()}

Return the current stats of the default column family Implemented by calling GetProperty with "rocksdb.stats" ### stats/2 ###


stats(DBHandle::db_handle(), CFHandle::cf_handle()) -> {ok, any()} | {error, any()}

Return the current stats of the specified column family Implemented by calling GetProperty with "rocksdb.stats" ### stop_backup/1 ###


stop_backup(BackupEngine::backup_engine()) -> ok

### sync_wal/1 ###


sync_wal(DbHandle::db_handle()) -> ok | {error, term()}

Sync the wal. Note that Write() followed by SyncWAL() is not exactly the same as Write() with sync=true: in the latter case the changes won't be visible until the sync is done. Currently only works if allow_mmap_writes = false in Options. ### updates_iterator/2 ###


updates_iterator(Db::db_handle(), Since::non_neg_integer()) -> {ok, Iterator::term()}

create a new iterator to retrive ethe transaction log since a sequce ### verify_backup/2 ###


verify_backup(BackupEngine::backup_engine(), BackupId::non_neg_integer()) -> ok | {error, any()}

checks that each file exists and that the size of the file matches our expectations. it does not check file checksum. ### write/3 ###


write(DBHandle, WriteActions, WriteOpts) -> Res

DBHandle = db_handle()
WriteActions = write_actions()
WriteOpts = write_options()
Res = ok | {error, any()}

Apply the specified updates to the database. ### write_batch/3 ###


write_batch(Db::db_handle(), Batch::batch_handle(), WriteOptions::write_options()) -> ok | {error, term()}

write the batch to the database ### write_binary_update/3 ###


write_binary_update(Iterator::term(), BinLog::binary(), WriteOptions::write_options()) -> ok | {error, term()}

apply a set of operation coming from a transaction log to another database. Can be useful to use it in slave mode.