SET RECOMMENDATIONS (Transact-SQL)

  • Makale

Applies to: Azure Synapse Analytics (dedicated SQL pool only)

Enables or disables the Azure Synapse distribution advisor for the current session. For instructions and samples on the use of the distribution advisor, see Distribution Advisor in Azure Synapse SQL.

Note

Distribution Advisor is currently in preview for Azure Synapse Analytics. Preview features are meant for testing only and should not be used on production instances or production data. As a preview feature, Distribution Advisor is subject to undergo changes in behavior or functionality. Please also keep a copy of your test data if the data is important.

Transact-SQL syntax conventions

Syntax

SET RECOMMENDATIONS { ON | OFF };

Arguments

ON

Enables Distribution Advisor for the current client session. Subsequently run queries will be taken into consideration for distribution strategy recommendations.

OFF

Turns Distribution Advisor OFF for the current client session. Returns advice as a string.

Remarks

Applies to Azure Synapse Analytics (dedicated SQL pool only) only.

Run this command when connected to a user database.

Permissions

Requires membership in the public role.

Examples

Following example will return distribution recommendation on selected TPC-DS queries. TPC-DS is an industry standard benchmark for analytical decision support workloads.

First, begin the distribution advisor recommendation collection and run sample queries.

-- Step 1: Turn the distribution advisor ON for the current client session
SET RECOMMENDATIONS ON;
GO

-- <insert your queries here, up to 100>
SELECT ss_store_sk, COUNT(*) FROM store_sales, store WHERE ss_store_sk = s_store_sk GROUP BY ss_store_sk;

SELECT cs_item_sk, COUNT(*) FROM catalog_sales, item WHERE cs_item_sk = i_item_sk  AND i_manufact_id > 100 GROUP BY cs_item_sk;

SELECT * FROM dbo.reason;

-- Turn the distribution advisor OFF for the current client session.
SET RECOMMENDATIONS OFF;
GO

Collect recommendations from the dynamic management view sys.dm_pdw_distrib_advisor_results for the current session. For example:


-- Step 2: view advice generated for the above workload
DECLARE @sessionid nvarchar(100), @recommendation nvarchar(max);
SELECT @sessionid = SESSION_ID();
SELECT @recommendation = recommendation FROM sys.dm_pdw_distrib_advisor_results WHERE session_id = @sessionid;
SELECT @recommendation;
GO

Next steps