jankotek/mapdb

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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.

Stars: 5.1k
Forks: 877
Open beginner issues: 0
Indexed issues: 193

Dominant language: Java
License: Apache-2.0
Last GitHub push: Aug 27, 2026
Latest indexed: Sep 20, 2026
Contributing guide: No contributing guide
Code of conduct: No code of conduct
Beginner labels: No beginner labels indexed
PR merge metrics: No merged PRs in 30d

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193 open issues indexed

Feature Request: Highly optimized custom String storage Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

jankotek/mapdb#1065 · Opened May 7, 2026
Switch from `org.lz4:lz4-java` to `at.yawk.lz4:lz4-java` due to CVE-2025-12183 & CVE-2025-66566. Open

Difficulty 2/5 1-3 hours Newbie friendliness 38/100

jankotek/mapdb#1064 · 1 comment · 6 reactions · Opened Dec 3, 2025
Map value keeps recreating Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

jankotek/mapdb#1063 · 1 comment · Opened Sep 26, 2025
custom key serializer is invalid Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

jankotek/mapdb#1062 · Opened Sep 17, 2025
MapDB 3.0.8 breaks Java 11 compatibility due to eclipse-collections version range Open

Difficulty 2/5 1-3 hours Newbie friendliness 52/100

jankotek/mapdb#1061 · 1 comment · Opened Aug 25, 2025
IndexTreeList java.lang.IndexOutOfBoundsException calling addFirst(E e) on an empty list Open

Difficulty 2/5 1-3 hours Newbie friendliness 62/100

jankotek/mapdb#1059 · Opened Jul 30, 2025
SortedTableMap fails with large datasets (30GB CSV) AssertionError Open

Difficulty 4/5 3-5 days Newbie friendliness 38/100

jankotek/mapdb#1057 · Opened Feb 23, 2025
Request for new release Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1055 · 6 comments · 5 reactions · Opened Dec 8, 2024
position beyond chunk 112 Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1053 · Opened Oct 21, 2024
java.lang.ArrayIndexOutOfBoundsException: Index 21 out of bounds for length 21 Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1052 · 1 comment · Opened Oct 21, 2024
Does it support multi-layer map nesting? Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

jankotek/mapdb#1051 · Opened Sep 4, 2024
Guava dependancy conflict Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1050 · Opened Aug 19, 2024
Blocking issue in dependency Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1049 · Opened Jul 18, 2024
Data corruption when using expireAfterCreate() and expireOverflow() with HashMapMaker Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

jankotek/mapdb#1046 · Opened Mar 27, 2024
API handle to get version of MapDB Open

Difficulty 3/5 1-2 days Newbie friendliness 42/100

jankotek/mapdb#1045 · 2 comments · Opened Feb 14, 2024
Trying to understand how it works Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1044 · Opened Feb 9, 2024
IndexOutOfBoundsException on DB.commit() Open

Difficulty 4/5 3-5 days Newbie friendliness 20/100

jankotek/mapdb#1043 · Opened Feb 8, 2024
When I execute db.commit() I get an alarm:Could not delete file: Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

jankotek/mapdb#1041 · 1 comment · Opened Feb 5, 2024
Vector Collection Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

jankotek/mapdb#1040 · Opened Jan 31, 2024
HTreeMap uses more direct memory than specified in HashMapMaker.expireStoreSize() Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

jankotek/mapdb#1039 · Opened Jan 2, 2024
compact is not working for WAL storage Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

jankotek/mapdb#1037 · Opened Dec 25, 2023
org.mapdb.DBException$DataCorruption: headPrev error Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

jankotek/mapdb#1036 · Opened Dec 22, 2023
Retrieving data after rollback will throw an exception Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

jankotek/mapdb#1034 · Opened Nov 23, 2023
MapDB is not reducing its size when all messages get deleted Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

jankotek/mapdb#1033 · 3 comments · Opened Nov 20, 2023
Using Bloom Filters to optimize overflowing HTreeMap reads Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

jankotek/mapdb#1032 · 3 reactions · Opened Sep 15, 2023
Is DB thread-safe? Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1023 · 1 reaction · Opened Aug 8, 2023
When I define a custom Serializer for key, the 'available' parameter in the deserialize method shows up as -1. Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

jankotek/mapdb#1021 · Opened May 21, 2023
Closing an HTreeMap instance also closes the associated DB instance Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

jankotek/mapdb#1020 · 1 reaction · Opened May 21, 2023
Working example using Kryo as a value serializer Open

Difficulty 3/5 1-2 days Newbie friendliness 25/100

jankotek/mapdb#1018 · Opened May 8, 2023
Temporary files cannot be deleted in mmap mode Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

jankotek/mapdb#1017 · Opened Apr 27, 2023
Cleaner hack does not release buffer for readonly mapdb files Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

jankotek/mapdb#1016 · Opened Apr 25, 2023
Missing delete method Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1015 · 1 comment · Opened Feb 23, 2023
Fun.HI() ClassCastException Open

Difficulty 4/5 3-5 days Newbie friendliness 30/100

jankotek/mapdb#1013 · 1 comment · Opened Dec 20, 2022
mapdb 3.0.8 fails to fileLoad mapDB file when readOnly set Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

jankotek/mapdb#1012 · Opened Nov 19, 2022
Fun.Tuple3Comparator etc Open

Difficulty 3/5 1-2 days Newbie friendliness 20/100

jankotek/mapdb#1011 · Opened Oct 29, 2022
how clear Cache? Open

Difficulty 2/5 1-3 hours Newbie friendliness 18/100

jankotek/mapdb#1010 · Opened Oct 29, 2022
add to list NoSQL Open

Difficulty 1/5 Under an hour Newbie friendliness 20/100

jankotek/mapdb#1009 · Opened Oct 29, 2022
Dependencies fail on maven - Guava Open

Difficulty 3/5 1-2 days Newbie friendliness 25/100

jankotek/mapdb#1008 · 2 comments · Opened Aug 2, 2022
NPE in ByteBufferVol which appears to corrupt header Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1007 · Opened Jul 18, 2022
Support for Map<Key,List<Value>> is planned in mapDB? Open

Difficulty 5/5 Over a week Newbie friendliness 15/100

jankotek/mapdb#1006 · Opened Apr 12, 2022
Exception in thread "main" java.lang.NoSuchMethodError: net.jpountz.xxhash.StreamingXXHash32.<init>(I)V Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1005 · Opened Feb 21, 2022
Use case about Map having Sets as values Open

Difficulty 5/5 Over a week Newbie friendliness 20/100

jankotek/mapdb#1004 · Opened Jan 20, 2022
Java module Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

jankotek/mapdb#1003 · 1 comment · Opened Dec 28, 2021
Exception in thread "main" org.mapdb.DBException$GetVoid: Record does not exist, recid=368 Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1001 · Opened Nov 27, 2021
java.lang.AssertionError: data were read beyond record size, check your serializer. version 1.0.9 Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#1000 · Opened Nov 3, 2021
"ArrayIndexOutOfBoundsException: Index 26 out of bounds for length 26" on calling getSize() Open

Difficulty 3/5 1-2 days Newbie friendliness 30/100

jankotek/mapdb#999 · 2 comments · Opened Oct 10, 2021
db.getStore().compact() hangs? Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#998 · 3 comments · Opened Oct 2, 2021
MapDB seems to cause invalid state in eclipse-collections LongObjectHashMap, Infinite loop in probeThree Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

jankotek/mapdb#997 · 1 comment · Opened Sep 7, 2021
v1.0.9 circular queue persistence Open

Difficulty 4/5 3-5 days Newbie friendliness 20/100

jankotek/mapdb#996 · Opened Jul 16, 2021
[Security][v 3.x] CVE-2019-10101 for Kotlin Open

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

jankotek/mapdb#995 · Opened Jun 18, 2021

jankotek/mapdb

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