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kandi has reviewed JDBM3 and discovered the below as its top functions. This is intended to give you an instant insight into JDBM3 implemented functionality, and help decide if they suit your requirements.
B*Tree with ConcurrentNavigableMap interface
Very fast for sequential read/write.
Small values stored inside tree nodes
Small values stored inside tree nodes, large values lazily fetched.
Self-balancing, great performance even with 1e12 items.
Delta compression on keys
Submaps (aka cursors) to view limited collection subsets
Custom comparators
H*Tree with ConcurrentMap interface
Optimized for random reads/writes
Small values stored inside tree nodes, large values lazily fetched.
Self-balancing, great performance even with 1e12 items.
TreeSet and HashSet which uses BTree and HTree without values
LinkedList, which implements bounded BlockingDeque (not implemented yet)
Multi code scalability (currently under testing)
Everything is thread safe
Reads should scale linearly with number of cores (as soon as it fits into cache)
All collection implements Concurrent interfaces
Some multi-core scalability with ReentrantReadWriteLock.
Instance cache
If data fits into cache, reads are almost as fast as in-memory collections.
Minimal overhead, works well even with 16MB heap.
Scales well into 64GB RAM heaps.
Various yet simple tuning options
Transactions
Single transaction per store, avoids concurrent modification stuff
Transactions are ACID (with limits for single concurrent transaction)
Option to disable transactions for fast inserts/updates
Low level key-value store
Various options for on-disk store (NIO, RAF, locking…)
Write performance not affected by store fragmentation
In-memory store option
Can read data from zip file with reasonable performance
Can read data from classpath resource, database is deployable over Java Web Start
Advanced defragmentation
Print store statistics
Transparent data encryption
Only 9 bytes overhead per record (for example BTree node)
Space efficient serialization
Custom code for most java.util and java.lang classes. For example Long(0) takes only single byte
Very small POJO serialization overhead, typically only 3 bytes per class + 1 byte for each field.
Mimic java serialization, fields can be transient, all classes needs to implement Serializable interface
Supports Externalizable
Possible to plug your own Serializer
Performance
Blazing fast 1 million inserts / 10 million reads per second (on my 5GHz machine, but you should get 300000 inserts p.s. easily)
Tightly optimized code
Uses NIO stuff you read about, but never see in action.
Minimal heap usage, prevents java.lang.OutOfMemoryError: GC overhead limit
Most logic done with primitives or arrays. Minimal stack usage.
Quick example
import org.apache.jdbm.*;
QUESTION
How to create or alter a DB schema dynamically (at run time) using Gramex FormHandler
Asked 2022-Apr-08 at 06:35I want to be able to (at run time) create or alter a DB schema dynamically on a particular event (e.g. click of a button) using FormHandler microservice of Gramex.
ANSWER
Answered 2022-Apr-08 at 06:20You can do it using queryfunction of FormHandler which can modify the query based on the query parameters passed in the url.
Refer the link below for more https://gramener.com/gramex/guide/formhandler/#formhandler-queryfunction
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