Lu, Huayi a24ca60074 DWS DEVELOPER 811 version

Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>
Co-authored-by: Lu, Huayi <luhuayi@huawei.com>
Co-committed-by: Lu, Huayi <luhuayi@huawei.com>

2023-01-19 13:37:49 +00:00

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Stream Operation Hints

Function

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

Syntax

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[no] broadcast|redistribute(table_list)

Parameter Description

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

table_list specifies the tables to be joined. For details, see Parameter Description.

Examples

Hint the query plan in Examples as follows:

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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

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