145 lines
4.9 KiB
Go
145 lines
4.9 KiB
Go
/*
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* Copyright 2017 Dgraph Labs, Inc. and Contributors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package badger
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import (
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"github.com/dgraph-io/badger/options"
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)
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// NOTE: Keep the comments in the following to 75 chars width, so they
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// format nicely in godoc.
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// Options are params for creating DB object.
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//
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// This package provides DefaultOptions which contains options that should
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// work for most applications. Consider using that as a starting point before
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// customizing it for your own needs.
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type Options struct {
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// 1. Mandatory flags
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// -------------------
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// Directory to store the data in. Should exist and be writable.
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Dir string
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// Directory to store the value log in. Can be the same as Dir. Should
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// exist and be writable.
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ValueDir string
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// 2. Frequently modified flags
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// -----------------------------
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// Sync all writes to disk. Setting this to true would slow down data
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// loading significantly.
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SyncWrites bool
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// How should LSM tree be accessed.
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TableLoadingMode options.FileLoadingMode
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// How should value log be accessed.
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ValueLogLoadingMode options.FileLoadingMode
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// How many versions to keep per key.
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NumVersionsToKeep int
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// 3. Flags that user might want to review
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// ----------------------------------------
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// The following affect all levels of LSM tree.
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MaxTableSize int64 // Each table (or file) is at most this size.
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LevelSizeMultiplier int // Equals SizeOf(Li+1)/SizeOf(Li).
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MaxLevels int // Maximum number of levels of compaction.
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// If value size >= this threshold, only store value offsets in tree.
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ValueThreshold int
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// Maximum number of tables to keep in memory, before stalling.
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NumMemtables int
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// The following affect how we handle LSM tree L0.
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// Maximum number of Level 0 tables before we start compacting.
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NumLevelZeroTables int
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// If we hit this number of Level 0 tables, we will stall until L0 is
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// compacted away.
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NumLevelZeroTablesStall int
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// Maximum total size for L1.
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LevelOneSize int64
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// Size of single value log file.
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ValueLogFileSize int64
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// Max number of entries a value log file can hold (approximately). A value log file would be
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// determined by the smaller of its file size and max entries.
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ValueLogMaxEntries uint32
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// Number of compaction workers to run concurrently.
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NumCompactors int
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// Transaction start and commit timestamps are manaVgedTxns by end-user. This
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// is a private option used by ManagedDB.
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managedTxns bool
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// 4. Flags for testing purposes
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// ------------------------------
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DoNotCompact bool // Stops LSM tree from compactions.
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maxBatchCount int64 // max entries in batch
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maxBatchSize int64 // max batch size in bytes
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// Open the DB as read-only. With this set, multiple processes can
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// open the same Badger DB. Note: if the DB being opened had crashed
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// before and has vlog data to be replayed, ReadOnly will cause Open
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// to fail with an appropriate message.
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ReadOnly bool
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// Truncate value log to delete corrupt data, if any. Would not truncate if ReadOnly is set.
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Truncate bool
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}
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// DefaultOptions sets a list of recommended options for good performance.
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// Feel free to modify these to suit your needs.
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var DefaultOptions = Options{
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DoNotCompact: false,
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LevelOneSize: 256 << 20,
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LevelSizeMultiplier: 10,
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TableLoadingMode: options.LoadToRAM,
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ValueLogLoadingMode: options.MemoryMap,
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// table.MemoryMap to mmap() the tables.
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// table.Nothing to not preload the tables.
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MaxLevels: 7,
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MaxTableSize: 64 << 20,
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NumCompactors: 3,
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NumLevelZeroTables: 5,
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NumLevelZeroTablesStall: 10,
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NumMemtables: 5,
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SyncWrites: true,
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NumVersionsToKeep: 1,
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// Nothing to read/write value log using standard File I/O
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// MemoryMap to mmap() the value log files
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ValueLogFileSize: 1 << 30,
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ValueLogMaxEntries: 1000000,
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ValueThreshold: 32,
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Truncate: false,
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}
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// LSMOnlyOptions follows from DefaultOptions, but sets a higher ValueThreshold so values would
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// be colocated with the LSM tree, with value log largely acting as a write-ahead log only. These
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// options would reduce the disk usage of value log, and make Badger act like a typical LSM tree.
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var LSMOnlyOptions = Options{}
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func init() {
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LSMOnlyOptions = DefaultOptions
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LSMOnlyOptions.ValueThreshold = 65500 // Max value length which fits in uint16.
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LSMOnlyOptions.ValueLogFileSize = 64 << 20 // Allow easy space reclamation.
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LSMOnlyOptions.ValueLogLoadingMode = options.FileIO
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}
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