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Questions tagged [mapdb]

MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap memory

MapDB provides concurrent Maps, Sets and Queues backed by disk storage or off-heap memory. It is a fast and easy to use embedded Java database engine. And it is completely free under Apache License. MapDB is free as speech and free as beer under Apache License 2.0.

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How to get SubMap from HTreeMap in MapDb

How to get SubMap from HTreeMap in MapDb ? We have SubMap function in BTreeMap. I need to remove different duplicates 10 key data. key5, value 5 and so on.
Hari
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Java - Cache HashMap with dynamic object size

I have a map of HashMap where Node is a class containing some info and most importantly containing a neighbors HashMap. My algorithm does random gets from the outer HashMap and puts in the inner HashMap, e.g. Node node = map.get(someInt);…
Nick Pavlakis
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Emergency storage for java

I am writing transport adapter for the messages(I receive the message from java native methods and send it to the RabbitMQ's queue) and I mustn't lose any messages(For example the connection to RabbitMQ's server is unavailable). I need an…
Viacheslav Kolybelkin
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mapdb performance slower compared to native hashmap

Hi I am trying to use MapDB offheap memory using 2.0.8, i tried 1.0.8 as well db = DBMaker.newMemoryDirectDB().transactionDisable().asyncWriteFlushDelay(100).make(); my tests: @Test public void testMapDBInsertionHash() { …
ameet chaubal
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How to write treemap with composite key in mapDB

We have https://github.com/jankotek/mapdb/blob/master/src/test/java/examples/TreeMap_Composite_Key.java example but is not working. Please provide some sample code.
Manish Kumar
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MapDB maps creation in parallel

I'm creating parallel Maps using MapDB - would like to know whether it's safe and can it be done in better way. also assume that each sales table query can result into million records. public static void main(String[] args){ DB db =…
Premraj
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MapDB durability with Memory mapped file and transaction disabled

I've got a question about using MapDB. When using MapDB with Memory mapped file and disabled transactions, will MapDB ensure durability of data even when JVM crashes or killed?
user2144247
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MapDB fixed structure of key and value

I would like to store a couple billion key,value pairs in MapDB. I have specific requirements: key = long (8 bytes) value = maximum 5 entries of (UUID + from-date + to-date), so 5 * 32 bytes = 160 Requirement is to have single threaded app: load by…
javacoder
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java.lang.IllegalAccessError: WAL not empty; commit first, than compact

I put "localDb.commit();" before every "localDb.compact();" but still get the exception: Exception in thread "Thread-0" java.lang.IllegalAccessError: WAL not empty; commit first, than compact at …
Po Zhou
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MapDb: is there any limitation for the number of maps

I'm using mapdb 1.0.7 and my question is: is there any limitation for the number of maps I can create with a single Db instance? Or is it theoretically unlimited. I've tested to create 1.000.000 maps with 25 entries in each of it. This works fine.…
thmarx
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Slow shutdown using AsyncWriteEngine in MapDb

I am using MapDB on Windows 7 with Java 8. My map is quite big - approximately 10.8 Gb in the .p data file. I am using the AsyncWriteEngine and it takes a long time to close. I observer it writes out very infrequently when there is no disk, memory…
user3521296
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How to access entries stored in MapDB BTreeMap in reverse order

I want to know if there is any way by which I can access entries stored in MapDB BTreeMap in reverse order. I know I can use descendingMap() but it is very slow and it involves a lot of CPU operations. Is there any other faster way? The Key Value…
Akash Mahajan
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Best way to store this in mapdb?

so I'm trying to do something with MapDB and I've run into a wall. I'll try describing it best I can: I have four pieces of data, we'll say it goes like this: 1) String action; //the name of the action itself 2) String categoryOfAction; //the…
rudy
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java.lang.NoClassDefFoundError: org/mapdb/DBMaker

I have problem using mapDB on GWT, i found error in this line: File utilizzo = new File("saveme.db"); DB db; db = DBMaker.newFileDB(utilizzo).closeOnJvmShutdown().make(); the error is in the third line and is: nov 20, 2014 11:20:30 AM …
Filippo Winston Maccarelli
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MapDB - submap behaviour

I've got a question about using MapDB, especially about querying a submap. I'm taking the code snippet from the official example at https://github.com/jankotek/MapDB/blob/release-1.0/src/test/java/examples/TreeMap_Composite_Key.java. This example is…
AnarchoEnte
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