meditime/vendor/github.com/dgraph-io/badger/options.go

420 lines
15 KiB
Go

/*
* Copyright 2017 Dgraph Labs, Inc. and Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package badger
import (
"github.com/dgraph-io/badger/options"
)
// Note: If you add a new option X make sure you also add a WithX method on Options.
// Options are params for creating DB object.
//
// This package provides DefaultOptions which contains options that should
// work for most applications. Consider using that as a starting point before
// customizing it for your own needs.
//
// Each option X is documented on the WithX method.
type Options struct {
// Required options.
Dir string
ValueDir string
// Usually modified options.
SyncWrites bool
TableLoadingMode options.FileLoadingMode
ValueLogLoadingMode options.FileLoadingMode
NumVersionsToKeep int
ReadOnly bool
Truncate bool
Logger Logger
EventLogging bool
// Fine tuning options.
MaxTableSize int64
LevelSizeMultiplier int
MaxLevels int
ValueThreshold int
NumMemtables int
NumLevelZeroTables int
NumLevelZeroTablesStall int
LevelOneSize int64
ValueLogFileSize int64
ValueLogMaxEntries uint32
NumCompactors int
CompactL0OnClose bool
LogRotatesToFlush int32
// When set, checksum will be validated for each entry read from the value log file.
VerifyValueChecksum bool
// BypassLockGaurd will bypass the lock guard on badger. Bypassing lock
// guard can cause data corruption if multiple badger instances are using
// the same directory. Use this options with caution.
BypassLockGuard bool
// Transaction start and commit timestamps are managed by end-user.
// This is only useful for databases built on top of Badger (like Dgraph).
// Not recommended for most users.
managedTxns bool
// 4. Flags for testing purposes
// ------------------------------
maxBatchCount int64 // max entries in batch
maxBatchSize int64 // max batch size in bytes
}
// DefaultOptions sets a list of recommended options for good performance.
// Feel free to modify these to suit your needs with the WithX methods.
func DefaultOptions(path string) Options {
return Options{
Dir: path,
ValueDir: path,
LevelOneSize: 256 << 20,
LevelSizeMultiplier: 10,
TableLoadingMode: options.MemoryMap,
ValueLogLoadingMode: options.MemoryMap,
// table.MemoryMap to mmap() the tables.
// table.Nothing to not preload the tables.
MaxLevels: 7,
MaxTableSize: 64 << 20,
NumCompactors: 2, // Compactions can be expensive. Only run 2.
NumLevelZeroTables: 5,
NumLevelZeroTablesStall: 10,
NumMemtables: 5,
SyncWrites: true,
NumVersionsToKeep: 1,
CompactL0OnClose: true,
VerifyValueChecksum: false,
// Nothing to read/write value log using standard File I/O
// MemoryMap to mmap() the value log files
// (2^30 - 1)*2 when mmapping < 2^31 - 1, max int32.
// -1 so 2*ValueLogFileSize won't overflow on 32-bit systems.
ValueLogFileSize: 1<<30 - 1,
ValueLogMaxEntries: 1000000,
ValueThreshold: 32,
Truncate: false,
Logger: defaultLogger,
EventLogging: true,
LogRotatesToFlush: 2,
}
}
// LSMOnlyOptions follows from DefaultOptions, but sets a higher ValueThreshold
// so values would be colocated with the LSM tree, with value log largely acting
// as a write-ahead log only. These options would reduce the disk usage of value
// log, and make Badger act more like a typical LSM tree.
func LSMOnlyOptions(path string) Options {
// Max value length which fits in uint16.
// Let's not set any other options, because they can cause issues with the
// size of key-value a user can pass to Badger. For e.g., if we set
// ValueLogFileSize to 64MB, a user can't pass a value more than that.
// Setting it to ValueLogMaxEntries to 1000, can generate too many files.
// These options are better configured on a usage basis, than broadly here.
// The ValueThreshold is the most important setting a user needs to do to
// achieve a heavier usage of LSM tree.
// NOTE: If a user does not want to set 64KB as the ValueThreshold because
// of performance reasons, 1KB would be a good option too, allowing
// values smaller than 1KB to be colocated with the keys in the LSM tree.
return DefaultOptions(path).WithValueThreshold(65500)
}
// WithDir returns a new Options value with Dir set to the given value.
//
// Dir is the path of the directory where key data will be stored in.
// If it doesn't exist, Badger will try to create it for you.
// This is set automatically to be the path given to `DefaultOptions`.
func (opt Options) WithDir(val string) Options {
opt.Dir = val
return opt
}
// WithValueDir returns a new Options value with ValueDir set to the given value.
//
// ValueDir is the path of the directory where value data will be stored in.
// If it doesn't exist, Badger will try to create it for you.
// This is set automatically to be the path given to `DefaultOptions`.
func (opt Options) WithValueDir(val string) Options {
opt.ValueDir = val
return opt
}
// WithSyncWrites returns a new Options value with SyncWrites set to the given value.
//
// When SyncWrites is true all writes are synced to disk. Setting this to false would achieve better
// performance, but may cause data loss in case of crash.
//
// The default value of SyncWrites is true.
func (opt Options) WithSyncWrites(val bool) Options {
opt.SyncWrites = val
return opt
}
// WithTableLoadingMode returns a new Options value with TableLoadingMode set to the given value.
//
// TableLoadingMode indicates which file loading mode should be used for the LSM tree data files.
//
// The default value of TableLoadingMode is options.MemoryMap.
func (opt Options) WithTableLoadingMode(val options.FileLoadingMode) Options {
opt.TableLoadingMode = val
return opt
}
// WithValueLogLoadingMode returns a new Options value with ValueLogLoadingMode set to the given
// value.
//
// ValueLogLoadingMode indicates which file loading mode should be used for the value log data
// files.
//
// The default value of ValueLogLoadingMode is options.MemoryMap.
func (opt Options) WithValueLogLoadingMode(val options.FileLoadingMode) Options {
opt.ValueLogLoadingMode = val
return opt
}
// WithNumVersionsToKeep returns a new Options value with NumVersionsToKeep set to the given value.
//
// NumVersionsToKeep sets how many versions to keep per key at most.
//
// The default value of NumVersionsToKeep is 1.
func (opt Options) WithNumVersionsToKeep(val int) Options {
opt.NumVersionsToKeep = val
return opt
}
// WithReadOnly returns a new Options value with ReadOnly set to the given value.
//
// When ReadOnly is true the DB will be opened on read-only mode.
// Multiple processes can open the same Badger DB.
// Note: if the DB being opened had crashed before and has vlog data to be replayed,
// ReadOnly will cause Open to fail with an appropriate message.
//
// The default value of ReadOnly is false.
func (opt Options) WithReadOnly(val bool) Options {
opt.ReadOnly = val
return opt
}
// WithTruncate returns a new Options value with Truncate set to the given value.
//
// Truncate indicates whether value log files should be truncated to delete corrupt data, if any.
// This option is ignored when ReadOnly is true.
//
// The default value of Truncate is false.
func (opt Options) WithTruncate(val bool) Options {
opt.Truncate = val
return opt
}
// WithLogger returns a new Options value with Logger set to the given value.
//
// Logger provides a way to configure what logger each value of badger.DB uses.
//
// The default value of Logger writes to stderr using the log package from the Go standard library.
func (opt Options) WithLogger(val Logger) Options {
opt.Logger = val
return opt
}
// WithEventLogging returns a new Options value with EventLogging set to the given value.
//
// EventLogging provides a way to enable or disable trace.EventLog logging.
//
// The default value of EventLogging is true.
func (opt Options) WithEventLogging(enabled bool) Options {
opt.EventLogging = enabled
return opt
}
// WithMaxTableSize returns a new Options value with MaxTableSize set to the given value.
//
// MaxTableSize sets the maximum size in bytes for each LSM table or file.
//
// The default value of MaxTableSize is 64MB.
func (opt Options) WithMaxTableSize(val int64) Options {
opt.MaxTableSize = val
return opt
}
// WithLevelSizeMultiplier returns a new Options value with LevelSizeMultiplier set to the given
// value.
//
// LevelSizeMultiplier sets the ratio between the maximum sizes of contiguous levels in the LSM.
// Once a level grows to be larger than this ratio allowed, the compaction process will be
// triggered.
//
// The default value of LevelSizeMultiplier is 10.
func (opt Options) WithLevelSizeMultiplier(val int) Options {
opt.LevelSizeMultiplier = val
return opt
}
// WithMaxLevels returns a new Options value with MaxLevels set to the given value.
//
// Maximum number of levels of compaction allowed in the LSM.
//
// The default value of MaxLevels is 7.
func (opt Options) WithMaxLevels(val int) Options {
opt.MaxLevels = val
return opt
}
// WithValueThreshold returns a new Options value with ValueThreshold set to the given value.
//
// ValueThreshold sets the threshold used to decide whether a value is stored directly in the LSM
// tree or separatedly in the log value files.
//
// The default value of ValueThreshold is 32, but LSMOnlyOptions sets it to 65500.
func (opt Options) WithValueThreshold(val int) Options {
opt.ValueThreshold = val
return opt
}
// WithNumMemtables returns a new Options value with NumMemtables set to the given value.
//
// NumMemtables sets the maximum number of tables to keep in memory before stalling.
//
// The default value of NumMemtables is 5.
func (opt Options) WithNumMemtables(val int) Options {
opt.NumMemtables = val
return opt
}
// WithNumLevelZeroTables returns a new Options value with NumLevelZeroTables set to the given
// value.
//
// NumLevelZeroTables sets the maximum number of Level 0 tables before compaction starts.
//
// The default value of NumLevelZeroTables is 5.
func (opt Options) WithNumLevelZeroTables(val int) Options {
opt.NumLevelZeroTables = val
return opt
}
// WithNumLevelZeroTablesStall returns a new Options value with NumLevelZeroTablesStall set to the
// given value.
//
// NumLevelZeroTablesStall sets the number of Level 0 tables that once reached causes the DB to
// stall until compaction succeeds.
//
// The default value of NumLevelZeroTablesStall is 10.
func (opt Options) WithNumLevelZeroTablesStall(val int) Options {
opt.NumLevelZeroTablesStall = val
return opt
}
// WithLevelOneSize returns a new Options value with LevelOneSize set to the given value.
//
// LevelOneSize sets the maximum total size for Level 1.
//
// The default value of LevelOneSize is 20MB.
func (opt Options) WithLevelOneSize(val int64) Options {
opt.LevelOneSize = val
return opt
}
// WithValueLogFileSize returns a new Options value with ValueLogFileSize set to the given value.
//
// ValueLogFileSize sets the maximum size of a single value log file.
//
// The default value of ValueLogFileSize is 1GB.
func (opt Options) WithValueLogFileSize(val int64) Options {
opt.ValueLogFileSize = val
return opt
}
// WithValueLogMaxEntries returns a new Options value with ValueLogMaxEntries set to the given
// value.
//
// ValueLogMaxEntries sets the maximum number of entries a value log file can hold approximately.
// A actual size limit of a value log file is the minimum of ValueLogFileSize and
// ValueLogMaxEntries.
//
// The default value of ValueLogMaxEntries is one million (1000000).
func (opt Options) WithValueLogMaxEntries(val uint32) Options {
opt.ValueLogMaxEntries = val
return opt
}
// WithNumCompactors returns a new Options value with NumCompactors set to the given value.
//
// NumCompactors sets the number of compaction workers to run concurrently.
// Setting this to zero stops compactions, which could eventually cause writes to block forever.
//
// The default value of NumCompactors is 2.
func (opt Options) WithNumCompactors(val int) Options {
opt.NumCompactors = val
return opt
}
// WithCompactL0OnClose returns a new Options value with CompactL0OnClose set to the given value.
//
// CompactL0OnClose determines whether Level 0 should be compacted before closing the DB.
// This ensures that both reads and writes are efficient when the DB is opened later.
//
// The default value of CompactL0OnClose is true.
func (opt Options) WithCompactL0OnClose(val bool) Options {
opt.CompactL0OnClose = val
return opt
}
// WithLogRotatesToFlush returns a new Options value with LogRotatesToFlush set to the given value.
//
// LogRotatesToFlush sets the number of value log file rotates after which the Memtables are
// flushed to disk. This is useful in write loads with fewer keys and larger values. This work load
// would fill up the value logs quickly, while not filling up the Memtables. Thus, on a crash
// and restart, the value log head could cause the replay of a good number of value log files
// which can slow things on start.
//
// The default value of LogRotatesToFlush is 2.
func (opt Options) WithLogRotatesToFlush(val int32) Options {
opt.LogRotatesToFlush = val
return opt
}
// WithVerifyValueChecksum returns a new Options value with VerifyValueChecksum set to
// the given value.
//
// When VerifyValueChecksum is set to true, checksum will be verified for every entry read
// from the value log. If the value is stored in SST (value size less than value threshold) then the
// checksum validation will not be done.
//
// The default value of VerifyValueChecksum is False.
func (opt Options) WithVerifyValueChecksum(val bool) Options {
opt.VerifyValueChecksum = val
return opt
}
// WithBypassLockGuard returns a new Options value with BypassLockGuard
// set to the given value.
//
// When BypassLockGuard option is set, badger will not acquire a lock on the
// directory. This could lead to data corruption if multiple badger instances
// write to the same data directory. Use this option with caution.
//
// The default value of BypassLockGuard is false.
func (opt Options) WithBypassLockGuard(b bool) Options {
opt.BypassLockGuard = b
return opt
}