How to create a constraints, indexes and nodes in a single procedure/plugin call? - neo4j

Question

similarly the code is for creating indexes and millions of nodes the respective methods. This is for creating fresh DB from JSON file.
I encounter the following error:
Exception: Cannot perform data updates in a transaction that has performed schema updates. Simple begin transaction and close it doesn't work?
After some time the session crashes in CreateNodes() method?
How exactly we separate the schema creation and data update?
Also refer the question I have posted before trying to get the similar answer, but no success. (I tried both injecting GraphDatabaseService as well as with Bolt Driver the result is the same).
How to use neo4j bolt session/transaction in a procedure as plugin for neo4j server extension?
for (int command = 4; command < inputNeo4jCommands.size(); command++) {
log.info(inputNeo4jCommands.get(command));
NEO4JCOMMANDS cmnd = NEO4JCOMMANDS.valueOf(inputNeo4jCommands.get(command).toUpperCase());
log.info(NEO4JCOMMANDS.valueOf(inputNeo4jCommands.get(command).toUpperCase()).toString());
if (NEO4JCOMMANDS.CONSTRAINT.equals(cmnd)) {
CreateConstraints1();
}
if (NEO4JCOMMANDS.INDEX.equals(cmnd)) {
CreateIndexes();
}
if (NEO4JCOMMANDS.MERGE.equals(cmnd)) {
log.info("started creating nodes........");
CreateNodes();
}
}
private void CreateIndexes1() {
log.info("Adding indexes.....");
log.info("into started adding index ......");
try (Transaction tx = db.beginTx()) {
log.info("got a transaction .....hence started adding index ......");
Iterator<Indx> itIndex = json2neo4j.getIndexes().iterator();
while (itIndex.hasNext()) {
Indx indx = itIndex.next();
Label lbl = Label.label(indx.getLabelname());
Iterable<IndexDefinition> indexes = db.schema().getIndexes(lbl);
if (indexes.iterator().hasNext()) {
for (IndexDefinition index : indexes) {
for (String key : index.getPropertyKeys()) {
if (!key.equals(indx.getColName())) {
db.schema().indexFor(lbl).on(indx.getColName());
}
}
}
} else {
db.schema().indexFor(lbl).on(indx.getColName());
}
tx.success();
tx.close();
}
log.info("\nIndexes Created..................Retured the method call ");
}
}

Answer 1

A lot of context is missing from your question and code examples, so it's hard to give a definite answer. Where is the exception thrown in the code example? There's no CreateNodes() method, so we can't find out why it's failing (Out Of Memory Error due to a transaction too large?).
However, there's an issue with your transaction management in the CreateIndexes1() method (not following the Java naming conventions, by the way):
try (Transaction tx = db.beginTx()) {
// ...
while (/* ... */) {
// ...
tx.success();
tx.close();
}
}
You're closing the transaction multiple times, when it's actually in a try-with-resources block where you don't need to close it yourself at all:
try (Transaction tx = db.beginTx()) {
// ...
while (/* ... */) {
// ...
}
tx.success();
}
I guess json2neo4j is the deserialization of a JSON describing the indices to create on labels. The logic is flawed: you try to create an index for a property as soon as you find an index for another property, when you should find out if an index for the current property exists and only create the index if it's missing then.
for (Indx indx : json2neo4j.getIndexes()) {
Label lbl = Label.label(indx.getLabelname());
boolean indexExists = false;
for (IndexDefinition index : db.schema().getIndexes(lbl)) {
for (String property : index.getPropertyKeys()) {
if (property.equals(indx.getColName())) {
indexExists = true;
break;
}
}
if (indexExists) {
break;
}
}
if (!indexExists) {
db.schema().indexFor(lbl).on(indx.getColName());
}
}