Add documentation about common patterns and pitfalls

[AlgorithmsAreCool]

Topics

LMDB Basics

• Overview of concepts and terms
• Usage scenarios
• Common problems and limitations (find some by looking at github issues)
  • Max Key size (511 bytes by default)
• How to use Async/Await safely (and when not to use it)
• Picking good config defaults
  • MaxReaders
  • MapSize
  • MaxDatabases
• DupSort and DupFixed
  • DupSort Values are limited to 511 bytes :/

Getting the best performance

• Performance expectations and knowing what things cost
• Picking good keys
  • Integer keys with IntegerKey set on database if possible
• Understanding write amplification and overhead
  • Small records can use more space than expected
• Hot to use strings as keys efficiently
• Importance of ReadOnly vs Normal Transactions
• Batching Writes
• Compression?
• The seductive danger of NO_SYNC
• Use the cursor API for faster reads (0-copy,
• Impact of lots of Databases
  • cache your db handles instead of reopening everytime
• DB Health and maintenance
  • When should you consider reallocating the DB to defragment

Advanced nonsense (might never get around to writing these)

• How to build your own indexes
• How to grow/reallocate the DB as quickly as possible
• Coordinating multiple lmdb environments
• Sharding to allow incremental reallocations