This tutorial describes how to create indexes to limit the number of index entries scanned for queries that includes a 本教程介绍如何创建索引，以限制针对包含$text expression and equality conditions.$text表达式和相等条件的查询扫描的索引项的数量。
A collection inventory contains the following documents:inventory集合包含以下文档：
{ _id: 1, dept: "tech", description: "lime green computer" }
{ _id: 2, dept: "tech", description: "wireless red mouse" }
{ _id: 3, dept: "kitchen", description: "green placemat" }
{ _id: 4, dept: "kitchen", description: "red peeler" }
{ _id: 5, dept: "food", description: "green apple" }
{ _id: 6, dept: "food", description: "red potato" }
Consider the common use case that performs text searches by individual departments, such as:考虑按单个部门执行文本搜索的常见用例，例如：
db.inventory.find( { dept: "kitchen", $text: { $search: "green" } } )
To limit the text search to scan only those documents within a specific 要将文本搜索限制为仅扫描特定dept, create a compound index that first specifies an ascending/descending index key on the field dept and then a text index key on the field description:dept内的那些文档，请创建一个复合索引，首先在字段dept上指定升序/降序索引键，然后在字段description上指定text索引键：
db.inventory.createIndex(
{
dept: 1,
description: "text"
}
)
Then, the text search within a particular department will limit the scan of indexed documents. 然后，特定部门内的文本搜索将限制索引文档的扫描。For example, the following query scans only those documents with 例如，以下查询仅扫描dept equal to kitchen:dept等于kitchen的文档：
db.inventory.find( { dept: "kitchen", $text: { $search: "green" } } )
text index cannot include any other special index types, such as multi-key or geospatial index fields.text索引不能包括任何其他特殊索引类型，如多键索引字段或地理空间索引字段。text index includes keys preceding the text index key, to perform a $text search, the query predicate must include equality match conditions on the preceding keys.text索引包含文本索引键之前的键，则要执行$text搜索，查询谓词必须在前面的键上包含相等匹配条件。text index, all text index keys must be listed adjacently in the index specification document.text索引时，索引规范文档中必须相邻列出所有text索引键。