Create a covering index for often-used, high-impact queries.

为最常用和最重要的查询创建覆盖索引。

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Covering indexes allow data storage within the index itself while sparse indexes exclude documents that do not contain the missing field.

Covered索引允许在索引本身里存储数据，而Sparse索引则会排除掉不包含索引字段的文档。

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The index is a combination of three sub-indices covering wealth, health and education.

该指数由3个次指标组成，涵盖了财富，健康和教育领域。

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Earlier this month, the index covering the Mumbai exchange touched levels not seen since February 2001, having climbed by more than 50% since April.

ECONOMIST: India's economy

Japan accounts for the largest country weighting in the MSCI EAFE (Europe, Australia, Far East) index, a global stock index covering more than 20 countries.

FORBES: When All Else Fails, Go Long

The ISM Non-Mfg Index, covering the services sector, also declined in March.

FORBES: Stock Market Warning Signs Becoming Ominous