After implementing CRUD operations within our custom datastore, we can further enhance our datastore functionality by adding features for effective data retrieval. This involves the process of indexing and searching. Data retrieval can be a complex operation, especially with large datasets. It involves scanning through the entire datastore and checking each value one by one - a cumbersome and slow process which gets slower as the size of our datastore grows. To improve the efficiency of data retrieval, we add indexing.

Indexing involves creating an additional structure, separate from our main datastore, that holds references to the data in the main store. We maintain a map where the value is the key, so we can search values by their keys. This makes the data retrieval process much faster. In our Python script, we create an index when we create data in our datastore and update it whenever we update the data. When deleting data, we also delete the corresponding index.

Along with indexing, exploiting search algorithms is a key aspect for efficient data retrieval. The search operation demonstrates this by allowing us to search by the value. It returns the key of the indexed value, if present, offering a way to quickly trace back data from its value. Our Python scripting example, simulating stock prices in a finance setting, highlights the use of search function while accessing and updating indexed data.

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    print(db.search(143.15))

class BasicDataStore:

    def __init__(self):

        self._store = {}

        self._index = {}

    def create(self, key, value):

        self._store[key] = value

        self._index[value] = key

    def retrieve(self, key):

        return self._store.get(key)

    def update(self, key, value):

        if key in self._store:

            old_value = self._store[key]

            self._store[key] = value

            del self._index[old_value]

            self._index[value] = key

            return True

        return False

    def delete(self, key):

        if key in self._store:

            value = self._store[key]

            del self._store[key]

            del self._index[value]

            return True

        return False