org.rocksdb

Interface AdvancedColumnFamilyOptionsInterface<T extends AdvancedColumnFamilyOptionsInterface<T>>

All Known Subinterfaces:

ColumnFamilyOptionsInterface<T>

All Known Implementing Classes:

ColumnFamilyOptions, Options

public interface AdvancedColumnFamilyOptionsInterface<T extends AdvancedColumnFamilyOptionsInterface<T>>

Advanced Column Family Options which are not mutable (i.e. present in AdvancedMutableColumnFamilyOptionsInterface Taken from include/rocksdb/advanced_options.h

Method Summary

Methods

Modifier and Type	Method and Description
int	bloomLocality() Control locality of bloom filter probes to improve cache miss rate.
CompactionOptionsFIFO	compactionOptionsFIFO() The options for FIFO compaction style
CompactionOptionsUniversal	compactionOptionsUniversal() The options needed to support Universal Style compactions
CompactionPriority	compactionPriority() Get the Compaction priority if level compaction is used for all levels
CompactionStyle	compactionStyle() Compaction style for DB.
java.util.List<CompressionType>	compressionPerLevel() Return the currently set CompressionType per instances.
boolean	forceConsistencyChecks() In debug mode, RocksDB run consistency checks on the LSM every time the LSM change (Flush, Compaction, AddFile).
boolean	inplaceUpdateSupport() Allows thread-safe inplace updates.
boolean	levelCompactionDynamicLevelBytes() Return if LevelCompactionDynamicLevelBytes is enabled.
long	maxCompactionBytes() Control maximum size of each compaction (not guaranteed)
int	maxWriteBufferNumberToMaintain() The total maximum number of write buffers to maintain in memory including copies of buffers that have already been flushed.
int	minWriteBufferNumberToMerge() The minimum number of write buffers that will be merged together before writing to storage.
int	numLevels() If level-styled compaction is used, then this number determines the total number of levels.
boolean	optimizeFiltersForHits() Returns the current state of the optimize_filters_for_hits setting.
T	setBloomLocality(int bloomLocality) Control locality of bloom filter probes to improve cache miss rate.
T	setCompactionOptionsFIFO(CompactionOptionsFIFO compactionOptionsFIFO) The options for FIFO compaction style
T	setCompactionOptionsUniversal(CompactionOptionsUniversal compactionOptionsUniversal) Set the options needed to support Universal Style compactions
T	setCompactionPriority(CompactionPriority compactionPriority) If level compactionStyle() == CompactionStyle.LEVEL, for each level, which files are prioritized to be picked to compact.
ColumnFamilyOptionsInterface	setCompactionStyle(CompactionStyle compactionStyle) Set compaction style for DB.
T	setCompressionPerLevel(java.util.List<CompressionType> compressionLevels) Different levels can have different compression policies.
T	setForceConsistencyChecks(boolean forceConsistencyChecks) In debug mode, RocksDB run consistency checks on the LSM every time the LSM change (Flush, Compaction, AddFile).
T	setInplaceUpdateSupport(boolean inplaceUpdateSupport) Allows thread-safe inplace updates.
T	setLevelCompactionDynamicLevelBytes(boolean enableLevelCompactionDynamicLevelBytes) If true, RocksDB will pick target size of each level dynamically.
T	setMaxCompactionBytes(long maxCompactionBytes) Maximum size of each compaction (not guarantee)
T	setMaxWriteBufferNumberToMaintain(int maxWriteBufferNumberToMaintain) The total maximum number of write buffers to maintain in memory including copies of buffers that have already been flushed.
T	setMinWriteBufferNumberToMerge(int minWriteBufferNumberToMerge) The minimum number of write buffers that will be merged together before writing to storage.
T	setNumLevels(int numLevels) Set the number of levels for this database If level-styled compaction is used, then this number determines the total number of levels.
T	setOptimizeFiltersForHits(boolean optimizeFiltersForHits) This flag specifies that the implementation should optimize the filters mainly for cases where keys are found rather than also optimize for keys missed.

Method Detail

setMinWriteBufferNumberToMerge

T setMinWriteBufferNumberToMerge(int minWriteBufferNumberToMerge)

The minimum number of write buffers that will be merged together before writing to storage. If set to 1, then all write buffers are flushed to L0 as individual files and this increases read amplification because a get request has to check in all of these files. Also, an in-memory merge may result in writing lesser data to storage if there are duplicate records in each of these individual write buffers. Default: 1

Parameters:

minWriteBufferNumberToMerge - the minimum number of write buffers that will be merged together.

Returns:

the reference to the current options.

minWriteBufferNumberToMerge

int minWriteBufferNumberToMerge()

The minimum number of write buffers that will be merged together before writing to storage. If set to 1, then all write buffers are flushed to L0 as individual files and this increases read amplification because a get request has to check in all of these files. Also, an in-memory merge may result in writing lesser data to storage if there are duplicate records in each of these individual write buffers. Default: 1

Returns:

the minimum number of write buffers that will be merged together.

setMaxWriteBufferNumberToMaintain

T setMaxWriteBufferNumberToMaintain(int maxWriteBufferNumberToMaintain)

The total maximum number of write buffers to maintain in memory including copies of buffers that have already been flushed. Unlike AdvancedMutableColumnFamilyOptionsInterface.maxWriteBufferNumber(), this parameter does not affect flushing. This controls the minimum amount of write history that will be available in memory for conflict checking when Transactions are used. When using an OptimisticTransactionDB: If this value is too low, some transactions may fail at commit time due to not being able to determine whether there were any write conflicts. When using a TransactionDB: If Transaction::SetSnapshot is used, TransactionDB will read either in-memory write buffers or SST files to do write-conflict checking. Increasing this value can reduce the number of reads to SST files done for conflict detection. Setting this value to 0 will cause write buffers to be freed immediately after they are flushed. If this value is set to -1, AdvancedMutableColumnFamilyOptionsInterface.maxWriteBufferNumber() will be used. Default: If using a TransactionDB/OptimisticTransactionDB, the default value will be set to the value of AdvancedMutableColumnFamilyOptionsInterface.maxWriteBufferNumber() if it is not explicitly set by the user. Otherwise, the default is 0.

Parameters:

maxWriteBufferNumberToMaintain - The maximum number of write buffers to maintain

Returns:

the reference to the current options.

maxWriteBufferNumberToMaintain

int maxWriteBufferNumberToMaintain()

The total maximum number of write buffers to maintain in memory including copies of buffers that have already been flushed.

Returns:

maxWriteBufferNumberToMaintain The maximum number of write buffers to maintain

setInplaceUpdateSupport

T setInplaceUpdateSupport(boolean inplaceUpdateSupport)

Allows thread-safe inplace updates. If inplace_callback function is not set, Put(key, new_value) will update inplace the existing_value iff * key exists in current memtable * new sizeof(new_value) ≤ sizeof(existing_value) * existing_value for that key is a put i.e. kTypeValue If inplace_callback function is set, check doc for inplace_callback. Default: false.

Parameters:

inplaceUpdateSupport - true if thread-safe inplace updates are allowed.

Returns:

the reference to the current options.

inplaceUpdateSupport

boolean inplaceUpdateSupport()

Allows thread-safe inplace updates. If inplace_callback function is not set, Put(key, new_value) will update inplace the existing_value iff * key exists in current memtable * new sizeof(new_value) ≤ sizeof(existing_value) * existing_value for that key is a put i.e. kTypeValue If inplace_callback function is set, check doc for inplace_callback. Default: false.

Returns:

true if thread-safe inplace updates are allowed.

setBloomLocality

T setBloomLocality(int bloomLocality)

Control locality of bloom filter probes to improve cache miss rate. This option only applies to memtable prefix bloom and plaintable prefix bloom. It essentially limits the max number of cache lines each bloom filter check can touch. This optimization is turned off when set to 0. The number should never be greater than number of probes. This option can boost performance for in-memory workload but should use with care since it can cause higher false positive rate. Default: 0

Parameters:

bloomLocality - the level of locality of bloom-filter probes.

Returns:

the reference to the current options.

bloomLocality

int bloomLocality()

Control locality of bloom filter probes to improve cache miss rate. This option only applies to memtable prefix bloom and plaintable prefix bloom. It essentially limits the max number of cache lines each bloom filter check can touch. This optimization is turned off when set to 0. The number should never be greater than number of probes. This option can boost performance for in-memory workload but should use with care since it can cause higher false positive rate. Default: 0

Returns:

the level of locality of bloom-filter probes.

See Also:

setBloomLocality(int)

setCompressionPerLevel

T setCompressionPerLevel(java.util.List<CompressionType> compressionLevels)

Different levels can have different compression policies. There are cases where most lower levels would like to use quick compression algorithms while the higher levels (which have more data) use compression algorithms that have better compression but could be slower. This array, if non-empty, should have an entry for each level of the database; these override the value specified in the previous field 'compression'.

NOTICE

If level_compaction_dynamic_level_bytes=true, compression_per_level[0] still determines L0, but other elements of the array are based on base level (the level L0 files are merged to), and may not match the level users see from info log for metadata.

If L0 files are merged to level - n, then, for i>0, compression_per_level[i] determines compaction type for level n+i-1.

Example

For example, if we have 5 levels, and we determine to merge L0 data to L4 (which means L1..L3 will be empty), then the new files go to L4 uses compression type compression_per_level[1].

If now L0 is merged to L2. Data goes to L2 will be compressed according to compression_per_level[1], L3 using compression_per_level[2]and L4 using compression_per_level[3]. Compaction for each level can change when data grows.

Default: empty

Parameters:

compressionLevels - list of CompressionType instances.

Returns:

the reference to the current options.

compressionPerLevel

java.util.List<CompressionType> compressionPerLevel()

Return the currently set CompressionType per instances.

See: setCompressionPerLevel(java.util.List)

Returns:

list of CompressionType instances.

setNumLevels

T setNumLevels(int numLevels)

Set the number of levels for this database If level-styled compaction is used, then this number determines the total number of levels.

Parameters:

numLevels - the number of levels.

Returns:

the reference to the current options.

numLevels

int numLevels()

If level-styled compaction is used, then this number determines the total number of levels.

Returns:

the number of levels.

setLevelCompactionDynamicLevelBytes

@Experimental(value="Turning this feature on or off for an existing DB can causeunexpected LSM tree structure so it\'s not recommended")
T setLevelCompactionDynamicLevelBytes(boolean enableLevelCompactionDynamicLevelBytes)

If true, RocksDB will pick target size of each level dynamically. We will pick a base level b >= 1. L0 will be directly merged into level b, instead of always into level 1. Level 1 to b-1 need to be empty. We try to pick b and its target size so that

1. target size is in the range of (max_bytes_for_level_base / max_bytes_for_level_multiplier, max_bytes_for_level_base]
2. target size of the last level (level num_levels-1) equals to extra size of the level.

At the same time max_bytes_for_level_multiplier and max_bytes_for_level_multiplier_additional are still satisfied.

With this option on, from an empty DB, we make last level the base level, which means merging L0 data into the last level, until it exceeds max_bytes_for_level_base. And then we make the second last level to be base level, to start to merge L0 data to second last level, with its target size to be 1/max_bytes_for_level_multiplier of the last levels extra size. After the data accumulates more so that we need to move the base level to the third last one, and so on.

Example

For example, assume max_bytes_for_level_multiplier=10, num_levels=6, and max_bytes_for_level_base=10MB.

Target sizes of level 1 to 5 starts with:

[- - - - 10MB]

with base level is level. Target sizes of level 1 to 4 are not applicable because they will not be used. Until the size of Level 5 grows to more than 10MB, say 11MB, we make base target to level 4 and now the targets looks like:

[- - - 1.1MB 11MB]

While data are accumulated, size targets are tuned based on actual data of level 5. When level 5 has 50MB of data, the target is like:

[- - - 5MB 50MB]

Until level 5's actual size is more than 100MB, say 101MB. Now if we keep level 4 to be the base level, its target size needs to be 10.1MB, which doesn't satisfy the target size range. So now we make level 3 the target size and the target sizes of the levels look like:

[- - 1.01MB 10.1MB 101MB]

In the same way, while level 5 further grows, all levels' targets grow, like

[- - 5MB 50MB 500MB]

Until level 5 exceeds 1000MB and becomes 1001MB, we make level 2 the base level and make levels' target sizes like this:

[- 1.001MB 10.01MB 100.1MB 1001MB]

and go on...

By doing it, we give max_bytes_for_level_multiplier a priority against max_bytes_for_level_base, for a more predictable LSM tree shape. It is useful to limit worse case space amplification.

max_bytes_for_level_multiplier_additional is ignored with this flag on.

Turning this feature on or off for an existing DB can cause unexpected LSM tree structure so it's not recommended.

Caution: this option is experimental

Default: false

Parameters:

enableLevelCompactionDynamicLevelBytes - boolean value indicating if LevelCompactionDynamicLevelBytes shall be enabled.

Returns:

the reference to the current options.

levelCompactionDynamicLevelBytes

@Experimental(value="Caution: this option is experimental")
boolean levelCompactionDynamicLevelBytes()

Return if LevelCompactionDynamicLevelBytes is enabled.

For further information see setLevelCompactionDynamicLevelBytes(boolean)

Returns:

boolean value indicating if levelCompactionDynamicLevelBytes is enabled.

setMaxCompactionBytes

T setMaxCompactionBytes(long maxCompactionBytes)

Maximum size of each compaction (not guarantee)

Parameters:

maxCompactionBytes - the compaction size limit

Returns:

the reference to the current options.

maxCompactionBytes

long maxCompactionBytes()

Control maximum size of each compaction (not guaranteed)

Returns:

compaction size threshold

setCompactionStyle

ColumnFamilyOptionsInterface setCompactionStyle(CompactionStyle compactionStyle)

Set compaction style for DB. Default: LEVEL.

Parameters:

compactionStyle - Compaction style.

Returns:

the reference to the current options.

compactionStyle

CompactionStyle compactionStyle()

Compaction style for DB.

Returns:

Compaction style.

setCompactionPriority

T setCompactionPriority(CompactionPriority compactionPriority)

If level compactionStyle() == CompactionStyle.LEVEL, for each level, which files are prioritized to be picked to compact. Default: CompactionPriority.ByCompensatedSize

Parameters:

compactionPriority - The compaction priority

Returns:

the reference to the current options.

compactionPriority

CompactionPriority compactionPriority()

Get the Compaction priority if level compaction is used for all levels

Returns:

The compaction priority

setCompactionOptionsUniversal

T setCompactionOptionsUniversal(CompactionOptionsUniversal compactionOptionsUniversal)

Set the options needed to support Universal Style compactions

Parameters:

compactionOptionsUniversal - The Universal Style compaction options

Returns:

the reference to the current options.

compactionOptionsUniversal

CompactionOptionsUniversal compactionOptionsUniversal()

The options needed to support Universal Style compactions

Returns:

The Universal Style compaction options

setCompactionOptionsFIFO

T setCompactionOptionsFIFO(CompactionOptionsFIFO compactionOptionsFIFO)

The options for FIFO compaction style

Parameters:

compactionOptionsFIFO - The FIFO compaction options

Returns:

the reference to the current options.

compactionOptionsFIFO

CompactionOptionsFIFO compactionOptionsFIFO()

The options for FIFO compaction style

Returns:

The FIFO compaction options

setOptimizeFiltersForHits

T setOptimizeFiltersForHits(boolean optimizeFiltersForHits)

This flag specifies that the implementation should optimize the filters mainly for cases where keys are found rather than also optimize for keys missed. This would be used in cases where the application knows that there are very few misses or the performance in the case of misses is not important.

For now, this flag allows us to not store filters for the last level i.e the largest level which contains data of the LSM store. For keys which are hits, the filters in this level are not useful because we will search for the data anyway.

NOTE: the filters in other levels are still useful even for key hit because they tell us whether to look in that level or go to the higher level.

Default: false

Parameters:

optimizeFiltersForHits - boolean value indicating if this flag is set.

Returns:

the reference to the current options.

optimizeFiltersForHits

boolean optimizeFiltersForHits()

Returns the current state of the optimize_filters_for_hits setting.

Returns:

boolean value indicating if the flag optimize_filters_for_hits was set.

setForceConsistencyChecks

T setForceConsistencyChecks(boolean forceConsistencyChecks)

In debug mode, RocksDB run consistency checks on the LSM every time the LSM change (Flush, Compaction, AddFile). These checks are disabled in release mode, use this option to enable them in release mode as well. Default: false

Parameters:

forceConsistencyChecks - true to force consistency checks

Returns:

the reference to the current options.

forceConsistencyChecks

boolean forceConsistencyChecks()

In debug mode, RocksDB run consistency checks on the LSM every time the LSM change (Flush, Compaction, AddFile). These checks are disabled in release mode.

Returns:

true if consistency checks are enforced