private void createUniqueKeyIndex()

in query/src/main/java/jetbrains/exodus/query/UniqueKeyIndicesEngine.java [125:176]
50 lines of code
13 McCabe index (conditional complexity)

    private void createUniqueKeyIndex(@NotNull final PersistentStoreTransaction txn,
                                      @NotNull final PersistentStoreTransaction snapshot,
                                      @NotNull final Index index) {
        if (logger.isDebugEnabled()) {
            logger.debug("Create index [" + index + ']');
        }

        final Environment environment = persistentStore.getEnvironment();
        final PersistentEntityStoreConfig config = persistentStore.getConfig();
        final PropertyTypes propertyTypes = persistentStore.getPropertyTypes();

        final List<IndexField> fields = index.getFields();
        final int propCount = fields.size();
        if (propCount == 0) {
            throw new EntityStoreException("Can't create unique key index on empty list of keys.");
        }
        SingleColumnTable indexTable = null;
        Comparable[] props = new Comparable[propCount];
        for (final String entityType : getEntityTypesToIndex(index)) {
            int i = 0;
            for (final Entity entity : snapshot.getAll(entityType)) {
                for (int j = 0; j < propCount; ++j) {
                    final IndexField field = fields.get(j);
                    if (field.isProperty()) {
                        if ((props[j] = persistentStore.getProperty(txn, (PersistentEntity) entity, field.getName())) == null) {
                            throw new EntityStoreException("Can't create unique key index with null property value: " + entityType + '.' + field.getName());
                        }
                    } else {
                        if ((props[j] = entity.getLink(field.getName())) == null) {
                            throw new EntityStoreException("Can't create unique key index with null link: " + entityType + '.' + field.getName());
                        }
                    }
                }
                if (indexTable == null) {
                    final String uniqueKeyIndexName = getUniqueKeyIndexName(index);
                    indexTable = new SingleColumnTable(txn, uniqueKeyIndexName,
                            environment.storeExists(uniqueKeyIndexName, txn.getEnvironmentTransaction()) ?
                                    StoreConfig.USE_EXISTING : StoreConfig.WITHOUT_DUPLICATES_WITH_PREFIXING);
                }
                ArrayByteIterable propsEntry = propertyTypes.dataArrayToEntry(props);
                if (!indexTable.getDatabase().add(txn.getEnvironmentTransaction(), propsEntry, LongBinding.longToCompressedEntry(entity.getId().getLocalId()))) {
                    ByteIterable oldEntityIdEntry = indexTable.getDatabase().get(txn.getEnvironmentTransaction(), propsEntry);
                    long oldEntityId = LongBinding.compressedEntryToLong(oldEntityIdEntry);
                    throw new EntityStoreException("Failed to insert unique key (already exists), index: " + index + ", values = " + Arrays.toString(props) + ", new entity = " + entity + ", old entity id = " + oldEntityId + ", index owner entity type = " + index.getOwnerEntityType());
                }
                if (++i % 100 == 0) {
                    txn.flush();
                }
            }
            txn.flush();
        }
    }