Help Center/ GaussDB(DWS)/ More Documents/ Developer Guide (Kuala Lumpur Region)/ Query Performance Optimization/ Query Improvement/ Hint-based Tuning/ Stream Operation Hints
Updated on 2022-08-16 GMT+08:00
View PDF
Share

Stream Operation Hints

Function

These hints specify a stream operation, which can be broadcast or redistribute.

Syntax

1
 
[no] broadcast|redistribute(table_list)

Parameter Description

  • no indicates that the specified hint will not be used for a join.

Examples

Hint the query plan in Examples as follows:

1
2
 
explain
select /*+ no redistribute(store_sales store_returns item store) leading(((store_sales store_returns item store) customer)) */ i_product_name product_name ...

In the original plan, the join result of store_sales, store_returns, item, and store is redistributed before it is joined with customer. After the hinting, the redistribution is disabled and the join order is retained. The optimized plan is as follows:

Parent topic: Hint-based Tuning