Help Center> GaussDB(for MySQL)> User Guide> Kernel Functions> Parallel Query> Usage> Application Scenarios
Updated on 2023-09-14 GMT+08:00
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Application Scenarios

Parallel query is suitable for the following scenarios:

  • Full table scans, index scans, index range scans, index reverse scans, index point queries, and index pushdown.
  • Single-table queries, multi-table joins, views, subqueries, and partial CTE queries.
  • Multiple JOIN algorithms, including BNL Join, BKA Join, HASH Join, Nested Loop Join, Semi Join, Anti Join, and Outer join.
  • Multiple subqueries, including conditional subqueries, scalar subqueries, some correlated subqueries, non-correlated subqueries, and derived tables.
  • Multiple data types, including Integer, Character, Floating Point, and Time.
  • Arithmetic expressions (+, -, *, %, /, |, and &), conditional expressions (<, <=, >, >=, <>, Between/And, In), logical operations (Or, And, Not), and common functions (Character, Integer, and Time), and aggregation functions (COUNT/SUM/AVG/MIN/MAX)

    The count aggregate function can be executed concurrently only when innodb_parallel_select_count is disabled.

  • Non-partitioned table queries, and queries for a single partition of partitioned tables
  • Order By, Group By/Distinct, Limit/Offset, Where/Having, and Column Projection
  • UNION/UNION ALL queries
  • EXPLAIN statements to view execution plans. Traditional Explain statements, Explain format=tree, and Explain format=json are included.
Parent topic: Usage