Indexes and Indexing
Introduction
Querying documents using a pre-existing database index is much faster because an index narrows down the set of documents to examine — see: the Query Troubleshooting topic.
When planning the indexes you need for your database, remember that while indexes make queries faster, they may also:
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Make writes slightly slower, because each index must be updated whenever a document is updated
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Make your Couchbase Lite database slightly larger.
Too many indexes may hurt performance. Optimal performance depends on designing and creating the right indexes to go along with your queries.
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Constraints
Couchbase Lite for ios 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.
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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:
{
"_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"
}SQL++
The code to create the index will look something like this:
CBLValueIndexConfiguration* config = [[CBLValueIndexConfiguration alloc]
initWithExpression: @[@"type", @"name"]];
[collection createIndexWithName:@"TypeNameIndex" config:config error: &error];QueryBuilder
| See the QueryBuilder topic to learn more about QueryBuilder. |
The code to create the index will look something like this:
CBLValueIndexItem *type = [CBLValueIndexItem property:@"type"];
CBLValueIndexItem *name = [CBLValueIndexItem property:@"name"];
CBLIndex *index = [CBLIndexBuilder valueIndexWithItems:@[type, name]];
[collection createIndex:index name:@"TypeNameIndex" error:&error];