The NoSQL data model in detail (IV.) Aggregation Type summary

backgroundin the first three articles, there are three types of databases in NoSQL that belong to the aggregation model: key-value, document-type, and column-family. The following is an analysis of the similarities and differences between the three aggregation data models so that we can understand the characteristics of each of them well. same Point

The common denominator of the three aggregation-oriented data models is that they all use aggregation, and there is an index key in the aggregation that can find its contents. When running on a cluster, aggregations are the focus, because the database must ensure that the data within the aggregation exists on the same node. Aggregation is the smallest unit of data for an update operation, and for transaction control, the aggregation is the operating unit, which is the appropriate size.

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The key-value data Model regards aggregation as an opaque whole, which means that the entire aggregation can only be detected based on the key, rather than just querying or getting part of it.

The aggregation of the document model is transparent to the data, so that only a subset of the data can be queried or fetched, but because the document has no schema, the database is not well tuned for the document structure when it wants to optimize storage and get some of the aggregations.

The column family model divides aggregations into column families, so that the database treats them as a unit of data within a row aggregation. There is some limitation to the structure of such aggregations, but the database can take advantage of this structure to improve its accessibility.

The NoSQL data model in detail (IV.) Aggregation Type summary