Merge pull request #185372 from LitKnd/external-tables-limitations-azuresqldb

Adding limitation for cursors and elastic query

Author: PRMerger15

articles/azure-sql/database/elastic-query-overview.md

@@ -137,10 +137,11 @@ Elastic query is included in the cost of Azure SQL Database. Note that topologie
 * Running your first elastic query can take up to a few minutes on smaller resources and Standard and General Purpose service tier. This time is necessary to load the elastic query functionality; loading performance improves with higher service tiers and compute sizes.
 * Scripting of external data sources or external tables from SSMS or SSDT is not yet supported.
 * Import/Export for SQL Database does not yet support external data sources and external tables. If you need to use Import/Export, drop these objects before exporting and then re-create them after importing.
-* Elastic query currently only supports read-only access to external tables. You can, however, use full T-SQL functionality on the database where the external table is defined. This can be useful to, e.g., persist temporary results using, for example, SELECT <column_list> INTO <local_table>, or to define stored procedures on the elastic query database that refer to external tables.
+* Elastic query currently only supports read-only access to external tables. You can, however, use full Transact-SQL functionality on the database where the external table is defined. This can be useful to, e.g., persist temporary results using, for example, SELECT <column_list> INTO <local_table>, or to define stored procedures on the elastic query database that refer to external tables.
 * Except for nvarchar(max), LOB types (including spatial types) are not supported in external table definitions. As a workaround, you can create a view on the remote database that casts the LOB type into nvarchar(max), define your external table over the view instead of the base table and then cast it back into the original LOB type in your queries.
 * Columns of nvarchar(max) data type in result set disable advanced batching technics used in Elastic Query implementation and may affect performance of query for an order of magnitude, or even two orders of magnitude in non-canonical use cases where large amount of non-aggregated data is being transferred as a result of query.
 * Column statistics over external tables are currently not supported. Table statistics are supported, but need to be created manually.
+* Cursors are not supported for external tables in Azure SQL Database.
 * Elastic query works with Azure SQL Database only. You cannot use it for querying a SQL Server instance.
 
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articles/azure-sql/database/elastic-query-vertical-partitioning.md

@@ -198,6 +198,7 @@ You can use regular SQL Server connection strings to connect your BI and data in
 ## Next steps
 
 * For an overview of elastic query, see [Elastic query overview](elastic-query-overview.md).
+* For limitations of elastic query, see [Preview limitations](elastic-query-overview.md#preview-limitations)
 * For a vertical partitioning tutorial, see [Getting started with cross-database query (vertical partitioning)](elastic-query-getting-started-vertical.md).
 * For a horizontal partitioning (sharding) tutorial, see [Getting started with elastic query for horizontal partitioning (sharding)](elastic-query-getting-started.md).
 * For syntax and sample queries for horizontally partitioned data, see [Querying horizontally partitioned data)](elastic-query-horizontal-partitioning.md)