Knowledge Base

Recreating Indexes and Constraints on 3.5

This article describes the process to drop and recreate all indexes and constraints on 3.5.x. This is a recommended step after upgrading from versions earlier then 3.5 so that all indexes and constraints can be rebuilt with the latest index provider and take advantage of native indexes.

More details on index providers can be found in the documentation: https://neo4j.com/docs/operations-manual/current/performance/index-configuration/schema-indexes/#index-configuration-index-providers

Customers who are upgrading from a 3.5 version prior to 3.5.8 may also want to do this process as noted in this Support Notification: https://support.neo4j.com/hc/en-us/articles/360027344873-Neo4j-3-5-x-Index-Inconsistency-Vulnerability-Fixed-in-Release-3-5-8

Step 1 - Generating Cypher Scripts to recreate Constraints:

Execute the following Cypher statement to generate a cypher script output which will be used to drop and create constraints:

CALL db.constraints() YIELD description
RETURN 'DROP ' + description + '; CREATE ' + description + ';'

This can be done in either the Neo4j Browser or cypher-shell. Depending on your version, you may need to strip out double quotes from the export.

Save this file, for example: recreate-constraints.cypher

Step 2 - Generating Cypher Scripts to recreate Indexes:

Execute the following Cypher statement to generate a cypher script output which will be used to drop and create constraints:

CALL db.indexes() YIELD description,type
WHERE type='node_label_property'
RETURN 'DROP ' + description + '; CREATE ' + description + ';'

Like the recreate constraints script, strip any double quotes and save the file: recreate-indexes.cypher

Step 3 (Optional) - Confirm Propery key sizes

If you are updating from 3.3 or earlier, it’s possible that the index creation could fail on string properties if any of the properties have a size greater then 4036 bytes. If you would like to check this prior to dropping and recreating, the following Cypher can be used to see if there are any values that would cause a failure:

match (n:<LABEL>)
with n, size(n.<property>) as prop_length
where prop_length >= 4036
return n.<property>, prop_length, id(n)
order by n.id desc

This will need to done for each Label/propery combination noted in steps 1 and 2. If any of the queries return any rows, you will need to either clean up / remove the nodes, or remove the drop/create from the generated cypher file for that index/constraint.

Step 4 - Confirm Index Provider

Check your configuration (neo4j.conf) and confirm that dbms.index.default_schema_provider is either commented out, or set to native-btree-1.0.

Step 5 - Run script to recreate indexes

In either the Neo4j Browser or via cypher-shell, paste in the recreate-indexes.cypher script and execute. Monitor for any errors.

Step 6 - Run script to recreate constraints

In either the Neo4j Browser or via cypher-shell, paste in the recreate-constraints.cypher script and execute. Monitor for any errors.

Step 7 - Confirm all indexes and constraints were populated, are online and are the correct index provider:

In either the Neo4j Browser or cypher-shell, run:

call db.indexes();

Verify that all indexes/constraints have a state of ONLINE, and a provider of:

{
  "version": "1.0",
  "key": "native-btree"
}