Calcite (https://calcite.apache.org/) is an incubator project of Apache. It is a framework for building JDBC or ODBC access databases. By customizing some adapters, you can access any type of data through sql. Recall that we used The SQL scenario only uses access relational databases such as MYSQL, ORACLE, etc., to query the data on HDFS through hive, but if we want to access a certain data structure in memory through the SQL interface (first of all, this structure has a relational model), the content in the file (For example, CSV files, ordinary files with a certain structure, in fact, these can be accessed through hive), access hbase and some NOSQL databases, and even want to access across data sources (join query between data in hive and data in mysql). The above basically represents the storage locations of various data that we usually come into contact with, and the problem that Calcite needs to solve is to let you find a way to build a relational model of these data, and then query the data through SQL
Adapters
Schema adaptersPermalink
A schema adapter allows Calcite to read particular kind of data, presenting the data as tables within a schema.
1)Cassandra adapter (calcite-cassandra)
2)CSV adapter (example/csv)
3)Druid adapter (calcite-druid)
4)Elasticsearch adapter (calcite-elasticsearch)
5)File adapter (calcite-file)
6)JDBC adapter (part of calcite-core)
7)MongoDB adapter (calcite-mongodb)
8)Pig adapter (calcite-pig)
9)Solr cloud adapter (solr-sql)
10)Spark adapter (calcite-spark)
11)Splunk adapter (calcite-splunk)
12)Eclipse Memory Analyzer (MAT) adapter (mat-calcite-plugin)
Apache Calcite has the following technical features:
Support standard SQL language;
Independent of programming languages and data sources, different front-ends and back-ends can be supported;
Support relational algebra, customizable logic planning rules and query engine optimized based on cost model;
Support materialized view management (create, discard, persist and auto-identify);
Lattice and Tile mechanisms based on materialized views for OLAP analysis;
Supports queries on streaming data.