# Neo4j 数据库内存参数优化

neo4j内存结构：

OS保留：OS内存、Lucene索引缓存

jvm堆：图查询、图管理、事务状态（可选）

neo4j memory management

jvm堆内存设置初始值和最大值一致，因为jvm更改堆大小时会触发full GC影响性能

syf@syf-ubuntu ~/o/neo4j-community-3.5.8 [1]> bin/neo4j-admin memrec --memory=8g
WARNING: Max 1024 open files allowed, minimum of 40000 recommended. See the Neo4j manual.
# Memory settings recommendation from neo4j-admin memrec:
#
# Assuming the system is dedicated to running Neo4j and has 8g of memory,
# we recommend a heap size of around 3600m, and a page cache of around 2g,
# and that about 2600m is left for the operating system, and the native memory
# needed by Lucene and Netty.
#
# Tip: If the indexing storage use is high, e.g. there are many indexes or most
# data indexed, then it might advantageous to leave more memory for the
# operating system.
#
# they do, the more heap memory you will need. However, don't allocate more
# than 31g of heap, since this will disable pointer compression, also known as
# "compressed oops", in the JVM and make less effective use of the heap.
#
# Tip: Setting the initial and the max heap size to the same value means the
# JVM will never need to change the heap size. Changing the heap size otherwise
# involves a full GC, which is desirable to avoid.
#
# Based on the above, the following memory settings are recommended:
dbms.memory.heap.initial_size=3600m
dbms.memory.heap.max_size=3600m
dbms.memory.pagecache.size=2g

https://neo4j.com/docs/operations-manual/3.5/performance/memory-configuration/