NoSQL データベース
Apache CouchDB is a schema-less document database that provides high performance, availability, and scalability. These features are not necessarily incompatible with a standards-compliant query language like SQL-92. The following sections show various schemes that the 本製品 offers to bridge the gap with relational SQL and a document database.
Automatic Schema Discovery
The 自動スキーマ検出 scheme automatically finds the data types in an Apache CouchDB object by scanning a configured number of rows of the object. You can use RowScanDepth, FlattenArrays, and FlattenObjects to control the relational representation of the collections in Apache CouchDB.
Parsing Nested Data
The 本製品 models the schemaless Apache CouchDB objects into relational tables and translates SQL queries into Apache CouchDB queries to get the requested data.
Free-Form Queries
The schema of the table is necessary to report metadata, but you can write フリーフォームクエリ not tied to the schema to select, insert, update, or delete data from columns that do not exist in the schema (without flattening).
Vertical Flattening
See 垂直フラット化 to process JSON arrays as separate tables.
JSON Functions
See JSON 関数 for query examples that can access specific nested data manually.Query Mapping
See クエリマッピング for more details on how various Apache CouchDB operations are represented as SQL.