apache · lordgamez · Jan 28, 2026 · Jun 23, 2026 · Jun 23, 2026
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ concurrency:
 env:
   DOCKER_CMAKE_FLAGS: -DDOCKER_VERIFY_THREAD=3 -DUSE_SHARED_LIBS= -DSTRICT_GSL_CHECKS=AUDIT -DCI_BUILD=ON -DENABLE_AWS=ON -DENABLE_KAFKA=ON -DENABLE_MQTT=ON -DENABLE_AZURE=ON -DENABLE_SQL=ON \
     -DENABLE_SPLUNK=ON -DENABLE_GCP=ON -DENABLE_OPC=ON -DENABLE_PYTHON_SCRIPTING=ON -DENABLE_LUA_SCRIPTING=ON -DENABLE_KUBERNETES=ON -DENABLE_TEST_PROCESSORS=ON -DENABLE_PROMETHEUS=ON \
-    -DENABLE_ELASTICSEARCH=ON -DENABLE_GRAFANA_LOKI=ON -DENABLE_COUCHBASE=ON -DENABLE_LLAMACPP=ON -DDOCKER_BUILD_ONLY=ON -DMINIFI_PERFORMANCE_TESTS=ON
+    -DENABLE_ELASTICSEARCH=ON -DENABLE_GRAFANA_LOKI=ON -DENABLE_COUCHBASE=ON -DENABLE_LLAMACPP=ON -DENABLE_LMDB=ON -DDOCKER_BUILD_ONLY=ON -DMINIFI_PERFORMANCE_TESTS=ON
   CCACHE_DIR: ${{ GITHUB.WORKSPACE }}/.ccache
 jobs:
   macos_xcode:
@@ -41,6 +41,7 @@ jobs:
         -DENABLE_LIBARCHIVE=ON
         -DENABLE_LLAMACPP=ON
         -DENABLE_KAFKA=ON
+        -DENABLE_LMDB=ON
         -DENABLE_LUA_SCRIPTING=ON
         -DENABLE_LZMA=ON
         -DENABLE_MQTT=ON
@@ -146,6 +147,7 @@ jobs:
         -DENABLE_LIBARCHIVE=ON
         -DENABLE_KAFKA=ON
         -DENABLE_LLAMACPP=ON
+        -DENABLE_LMDB=ON
         -DENABLE_LUA_SCRIPTING=ON
         -DENABLE_LZMA=ON
         -DENABLE_MQTT=ON
@@ -244,10 +246,11 @@ jobs:
         -DENABLE_EXECUTE_PROCESS=ON
         -DENABLE_GCP=ON
         -DENABLE_GRAFANA_LOKI=ON
+        -DENABLE_KAFKA=ON
         -DENABLE_KUBERNETES=ON
         -DENABLE_LIBARCHIVE=ON
         -DENABLE_LLAMACPP=ON
-        -DENABLE_KAFKA=ON
+        -DENABLE_LMDB=ON
         -DENABLE_LUA_SCRIPTING=ON
         -DENABLE_LZMA=ON
         -DENABLE_MQTT=ON

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -742,15 +742,16 @@ endif()
 
 cpack_add_component_group(extensions DISPLAY_NAME "Extensions" EXPANDED)
 set(EXTENSIONS_ENABLED_BY_DEFAULT (
+    minifi-archive-extensions
     minifi-aws
     minifi-azure
     minifi-civet-extensions
     minifi-elasticsearch
     minifi-gcp
     minifi-grafana-loki
-    minifi-archive-extensions
-    minifi-mqtt-extensions
     minifi-kafka
+    minifi-lmdb
+    minifi-mqtt-extensions
     minifi-pdh
     minifi-prometheus
     minifi-rocksdb-repos

diff --git a/CONFIGURE.md b/CONFIGURE.md
@@ -625,7 +625,7 @@ The Flow File Repository can be configured with the `nifi.flowfile.repository.cl
     # in minifi.properties
     nifi.flowfile.repository.class.name=NoOpRepository  # VolatileFlowFileRepository can also be used which is an alias for NoOpRepository
 
-The Content Repository can be configured with the `nifi.content.repository.class.name` property. If not specified, it uses the `DatabaseContentRepository` class by default, which persists the content in a RocksDB database. `DatabaseContentRepository` is also the default value specified in the minifi.properties file. Alternatively it can be configured to use a `VolatileContentRepository` that keeps the state in memory (so the state gets lost upon restart), or the `FileSystemRepository` to keep the state in regular files.
+The Content Repository can be configured with the `nifi.content.repository.class.name` property. If not specified, it uses the `DatabaseContentRepository` class by default, which persists the content in a RocksDB database. `DatabaseContentRepository` is also the default value specified in the minifi.properties file. Alternatively it can be configured to use a `VolatileContentRepository` that keeps the state in memory (so the state gets lost upon restart), the `FileSystemRepository` to keep the state in regular files, or `LmdbContentRepository` that uses LMDB database as an alternative to RocksDB.
 
 **NOTE:** RocksDB database has a limit of 4GB for the size of a database object. Due to this if you expect to process larger flow files than 4GB you should use the `FileSystemRepository`. The downside of using `FileSystemRepository` is that it does not have the transactional guarantees of the RocksDB repository implementation.
 
@@ -745,6 +745,18 @@ RocksDB options can also be overridden for a specific repository using the `nifi
     nifi.provenance.repository.rocksdb.options.use_direct_reads=false
     nifi.state.storage.rocksdb.options.use_direct_io_for_flush_and_compaction=false
 
+### Configuring LMDB content repository
+
+There is an alternative content repository that can be used: the LMDB database. When `LmdbContentRepository` is set, LMDB is used for storing content, which is a memory-mapped, fast (especially for reads), low-footprint, key-value database. It can be a good alternative on memory-limited edge devices, but each use case should be evaluated separately. The caveats of using this database are the following:
+
+- Single writer only — concurrent writes are serialized, which can be a bottleneck for write-heavy workloads
+- Database file never shrinks automatically — occasional large flow files could keep the database size permanently high on disk and in the reserved virtual address space
+- No compression - stores everything uncompressed on disk
+- The maximum database size must be set upfront, which is done in the minifi.properties file with the following property, with the current default value set to 10 GB:
+
+    # in minifi.properties
+    nifi.content.repository.lmdb.max.db.size=10 GB
+
 #### Shared database
 
 It is also possible to use a single database to store multiple repositories with the `minifidb://` scheme.

diff --git a/cmake/LMDB.cmake b/cmake/LMDB.cmake
@@ -0,0 +1,42 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+include(FetchContent)
+
+set(PATCH_FILE_1 "${CMAKE_SOURCE_DIR}/thirdparty/lmdb/add-cmake-file.patch")
+if (WIN32)
+    set(PATCH_FILE_2 "${CMAKE_SOURCE_DIR}/thirdparty/lmdb/fix-windows-symbols.patch")
+    set(PC ${Bash_EXECUTABLE}  -c "set -x &&\
+        (\\\"${Patch_EXECUTABLE}\\\" -p1 -R -s -f --dry-run -i \\\"${PATCH_FILE_1}\\\" || \\\"${Patch_EXECUTABLE}\\\" -p1 -N -i \\\"${PATCH_FILE_1}\\\") &&\
+        (\\\"${Patch_EXECUTABLE}\\\" -p1 -R -s -f --dry-run -i \\\"${PATCH_FILE_2}\\\" || \\\"${Patch_EXECUTABLE}\\\" -p1 -N -i \\\"${PATCH_FILE_2}\\\")")
+else()
+    set(PC ${Bash_EXECUTABLE}  -c "set -x &&\
+        (\\\"${Patch_EXECUTABLE}\\\" -p1 -R -s -f --dry-run -i \\\"${PATCH_FILE_1}\\\" || \\\"${Patch_EXECUTABLE}\\\" -p1 -N -i \\\"${PATCH_FILE_1}\\\")")
+endif()
+
+FetchContent_Declare(
+        lmdb
+        URL      https://github.com/LMDB/lmdb/archive/refs/tags/LMDB_1.0.0-branch.tar.gz
+        URL_HASH SHA256=8d3e790194e43a72f172f34c442ea4737b2d1433fc0983f2ef70bae999bc2d28
+        PATCH_COMMAND "${PC}"
+        SOURCE_SUBDIR "libraries/liblmdb"
+        SYSTEM
+)
+
+FetchContent_MakeAvailable(lmdb)
+
+set(LMDB_INCLUDE_DIR "${lmdb_SOURCE_DIR}/libraries/liblmdb")
diff --git a/cmake/MiNiFiOptions.cmake b/cmake/MiNiFiOptions.cmake
@@ -90,6 +90,7 @@ endif()
 add_minifi_option(ENABLE_ALL "Enables all extensions" OFF)
 add_minifi_option(ENABLE_CIVET "Enables CivetWeb components." ON)
 add_minifi_option(ENABLE_ROCKSDB "Enables the RocksDB extension." ON)
+add_minifi_option(ENABLE_LMDB "Enables the LMDB extension." ON)
 add_minifi_option(ENABLE_LIBARCHIVE "Enables the lib archive extensions." ON)
 add_minifi_option(ENABLE_LZMA "Enables the liblzma build" ON)
 add_minifi_option(ENABLE_BZIP2 "Enables the bzip2 build" ON)

diff --git a/conf/minifi.properties.in b/conf/minifi.properties.in
@@ -54,6 +54,9 @@ nifi.content.repository.class.name=DatabaseContentRepository
 # nifi.database.content.repository.rocksdb.compaction.period=2 min
 # nifi.database.content.repository.optimize.for.small.db.cache.size=8 MB
 
+## Relates to the internal workings of the LMDB backend
+# nifi.content.repository.lmdb.max.db.size=10 GB
+
 # setting this value to "0" enables synchronous deletion
 # nifi.database.content.repository.purge.period = 1 sec
 

diff --git a/extensions/lmdb/CMakeLists.txt b/extensions/lmdb/CMakeLists.txt
@@ -0,0 +1,37 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+if (NOT (ENABLE_ALL OR ENABLE_LMDB))
+    return()
+endif()
+
+include(LMDB)
+
+include(${CMAKE_SOURCE_DIR}/extensions/ExtensionHeader.txt)
+
+file(GLOB SOURCES  "*.cpp")
+
+add_minifi_library(minifi-lmdb SHARED ${SOURCES})
+
+target_include_directories(minifi-lmdb PUBLIC ${LMDB_INCLUDE_DIR})
+target_link_libraries(minifi-lmdb PUBLIC lmdb)
+target_link_libraries(minifi-lmdb PUBLIC minifi-api minifi-extension-framework)
+target_link_libraries(minifi-lmdb PRIVATE $<LINK_ONLY:core-minifi>)
+
+register_extension(minifi-lmdb "LMDB" LMDB "This Enables persistent provenance, flowfile, and content repositories using LMDB" "extensions/lmdb/tests")