Indexing your Data

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    Description — Couchbase Lite database data model concepts - indexes
    Related Content — Databases | Documents | Indexing |

    Introduction

    Before we begin querying documents, let’s briefly mention the importance of having an appropriate and balanced approach to indexes.

    Creating indexes can speed up the performance of queries. A query will typically return results more quickly if it can take advantage of an existing database index to search, narrowing down the set of documents to be examined.

    Constraints
    Couchbase Lite for net does not currently support partial value indexes; indexes with non-property expressions. You should only index with properties that you plan to use in the query.

    Creating a new index

    You can use SQL++ or QueryBuilder syntaxes to create an index

    Example 2 creates a new index for the type and name properties, shown in this data model:

    Example 1. Data Model
    {
        "_id": "hotel123",
        "type": "hotel",
        "name": "The Michigander",
        "overview": "Ideally situated for exploration of the Motor City and the wider state of Michigan. Tripadvisor rated the hotel ...",
        "state": "Michigan"
    }

    N1QL

    The code to create the index will look something like this:

    Example 2. Create index
    var db = _database;
    string[] indexProperties = new string[] {"type", "name" };
    var config = new ValueIndexConfiguration(indexProperties);
    db.CreateIndex("TypeNameIndex", config);

    QueryBuilder

    The code to create the index will look something like this:

    Example 3. Create index with QueryBuilder
    // For value types, this is optional but provides performance enhancements
    var db = _database;
    var index = IndexBuilder.ValueIndex(
        ValueIndexItem.Expression(Expression.Property("type")),
        ValueIndexItem.Expression(Expression.Property("name"))); (1)
    db.CreateIndex("TypeNameIndex", index);

    Summary

    When planning the indexes you need for your database, remember that while indexes make queries faster, they may also:

    • Make writes slightly slower, because each index must be updated whenever a document is updated

    • Make your Couchbase Lite database slightly larger.

    So too many indexes may hurt performance. Optimal performance depends on designing and creating the right indexes to go along with your queries.