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For unordered access as defined in the java.util.Map interface, the java.util.concurrent.ConcurrentHashMap implements java.util.concurrent.ConcurrentMap. [2] The mechanism is a hash access to a hash table with lists of entries, each entry holding a key, a value, the hash, and a next reference.
A concurrent hash table or concurrent hash map is an implementation of hash tables allowing concurrent access by multiple threads using a hash function. [1] [2] Concurrent hash tables represent a key concurrent data structure for use in concurrent computing which allow multiple threads to more efficiently cooperate for a computation among ...
InfinityDB can be accessed as an extended standard java.util.concurrent.ConcurrentNavigableMap, or via a low-level 'ItemSpace' API. The ConcurrentNavigableMap interface is a subinterface of java.util.Map but has special ordering and concurrency methods: this is the same API as java.util.concurrent.ConcurrentSkipListMap.
Trino is an open-source distributed SQL query engine designed to query large data sets distributed over one or more heterogeneous data sources. [1] Trino can query data lakes that contain a variety of file formats such as simple row-oriented CSV and JSON data files to more performant open column-oriented data file formats like ORC or Parquet [2] [3] residing on different storage systems like ...
Covering indexes are each for a specific table. Queries which JOIN/ access across multiple tables, may potentially consider covering indexes on more than one of these tables. [7] A covering index can dramatically speed up data retrieval but may itself be large due to the additional keys, which slow down data insertion and update.
Apache Iceberg is a high performance open-source format for large analytic tables. Iceberg enables the use of SQL tables for big data while making it possible for engines like Spark, Trino, Flink, Presto, Hive, Impala, StarRocks, Doris, and Pig to safely work with the same tables, at the same time. [1] Iceberg is released under the Apache ...
One DAO for each table. One DAO for all the tables for a particular DBMS. Where the SELECT query is limited only to its target table and cannot incorporate JOINS, UNIONS, subqueries and Common Table Expressions (CTEs) Where the SELECT query can contain anything that the DBMS allows.
After freezing the database no more schema alterations take place. Relations among tables are mapped in the same way: by convention. For instance, to create a one-to-many relationship between two tables one assigns an array to the property bearing the name of the target table. This automatically creates the table as well as the required columns.