What's the correct way to remove old db and start a fresh one?

Neo4j Graph Platform
1

I don't know what the correct way to start an empty db. I know that I can remove all nodes and relations by doing

match (n)  
with n limit 10000  
DETACH DELETE n;

over and over again until everything is gone, but this is not reasonable to do on a huge database.

Is there not a simpler way to remove everything?

2

Hello @Rogie :slight_smile:

With apoc:

CALL apoc.periodic.iterate('MATCH (n) RETURN n', 'DETACH DELETE n', {batchSize:1000, iterateList:true})

Regards,
Cobra

3

Trying this now, but it seems extremely slow. Has been running for an hour and still not complete.

4

How many nodes and relationships do you have?

Did you put index on them?

5

Around 10 million nodes. Each type has a uniqueness constraint for some attribute.

6

Do you have enough RAM and a good processor?

The request I gave you is the fastest one to delete everything in the database :slight_smile:

Regards,
Cobra

7

How long should I expect it to take? There are 8GiB of ram on the system.

8

To be honest I don't know, 8Go looks small for a database with 10 millions nodes :confused:

You just need to wait :confused:

9

How much RAM do you suggest to have in this case?

10

I know there is hardware sizing but I never test it :slight_smile:

11

Hi @Rogie,

If you are using Neo4j 4.x you can switch to the system database using :use system and then run drop database <database_name> Then to create a new empty database run create database <database_name> .

2 Likes
12

Why not simply create a new database?
Anyway, if you insist on deleting the objects don't forget to erase the indexes and constraints (schema). Just look up the command I don't remember the syntax.

13

To be clear, this solution only works for Enterprise Edition.