DatabaseDatabase
Databases are computer systems designed for storing data.
This note serves as a link to connect database-related notes.
[[ACID]]
[[Optimistic Locking]]/[[Pessimistic Locking]]
[[Database I... indexes are data structures that databases keep on the side to improve the speed of reading the primary data, at the cost of increased storage usage and speed of writes.
Indexes are derived from the primary data, and in many databases you can safely add and remove the without affecting the original data - just the speed of query execution.
Indexes optimize the speed of read queries, usually at the cost of speed of write queries. It's difficult to use a secondary data structure to improve write speeds, as the fastest way to write something is to write it only once - while indexes are active, in addition to writing the data to the database, you also need to update the indexes, which slows the writes down.
Some ways of organizing and indexing data:
- In Memory Hash Map IndexIn Memory Hash Map Index
Let's imagine we are making a simple [[Key Value Database]] that writes entries to a file (e.g. [[Append Only FIle]]), and we want to implement an in-memory hash map as an index.
Storing data on di... - LSM TreeLSM Tree
Log-Structured Merge Tree is a [[Data Structure]] optimized for write-heavy workloads, used by storage engines like [[Cassandra]] and HBase.
When a write comes in, we add it to an in-memory balanc...
Status: #📥
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