Whether the provider exposes aggregate columns that are also available as child tables. Ignored if TableSupport is not set to Full.

データ型

bool

デフォルト値

false

解説

The 本製品 will expose array fields within a bucket as a separate child table, such as in the Games_scores example described in 自動スキーマ検出. By default the 本製品 will also expose these array fields as JSON aggregates on the base table. For example, either of these queries would return information on game scores:

/* Return each score as an individual row */ 
SELECT value FROM Games_scores;

/* Return all scores for each Game as a JSON string */
SELECT scores FROM Games;

Since these aggregates are exposed on the base table, they will be generated even when the information they contain is redundant. For example, when performing this join the scores aggregate on Games is populated as well as the value column on Games_scores. Internally this causes two copies of the scores data to be transferred from Couchbase.

/* Retrieves score data twice, once for Games.scores and once for Games_scores.value */
SELECT * FROM Games INNER JOIN Games_scores ON Games.[Document.Id] = Games_scores.[Document.Id]

This option can be used to prevent the aggregate field from being exposed when the same information is also available from a child table. In the games example, setting this option to true means that the Games table would only expose a primary key column. The only way to retrieve information about scores would be the child table, so score data would only be read once from Couchbase.

/* Only exposes Document.Id, not scores */
SELECT * FROM Games;

/* Only retrieves score data once for Games_scores.value */
SELECT * FROM Games INNER JOIN Games_scores ON Games.[Document.Id] = Games_scores.[Document.Id]

Note that this option overrides FlattenArrays, since all data from flattened arrays is also avaialable as child tables. If this option is set then no array flattening is performed, even if FlattenArrays is set to a value over 0.