Capacity limits for dedicated SQL pool in Azure Synapse Analytics

Maximum values allowed for various components of dedicated SQL pool in Azure Synapse Analytics.

Workload management

Category	Description	Maximum
Data Warehouse Units (DWU)	Max DWU for a single dedicated SQL pool	Gen1: DW6000 Gen2: DW30000c
Data Warehouse Units (DWU)	Default DTU per server	54,000 By default, each SQL server (for example, myserver.database.windows.net) has a DTU Quota of 54,000, which allows up to DW6000c. This quota is simply a safety limit. You can increase your quota by creating a support ticket and selecting Quota as the request type. To calculate your DTU needs, multiply the 7.5 by the total DWU needed, or multiply 9 by the total cDWU needed. For example: DW6000 x 7.5 = 45,000 DTUs DW7500c x 9 = 67,500 DTUs. You can view your current DTU consumption from the SQL server option in the portal. Both paused and unpaused databases count toward the DTU quota.
Database connection	Maximum Concurrent open sessions	1024 The number of concurrent open sessions will vary based on the selected DWU. DWU1000c and above support a maximum of 1024 open sessions. DWU500c and below, support a maximum concurrent open session limit of 512. Note, there are limits on the number of queries that can execute concurrently. When the concurrency limit is exceeded, the request goes into an internal queue where it waits to be processed.
Database connection	Maximum memory for prepared statements	20 MB
Workload management	Maximum concurrent queries	128 A maximum of 128 concurrent queries will execute and remaining queries will be queued. The number of concurrent queries can decrease when users are assigned to higher resource classes or when the data warehouse unit setting is lowered. Some queries, like DMV queries, are always allowed to run and do not impact the concurrent query limit. For more information on concurrent query execution, see the concurrency maximums article.
tempdb	Maximum GB	399 GB per DW100c. For example, at DWU1000c, tempdb is sized to 3.99 TB.

Database objects

Category	Description	Maximum
Database	Max size	Gen1: 240 TB compressed on disk. This space is independent of tempdb or log space, and therefore this space is dedicated to permanent tables. Clustered columnstore compression is estimated at 5X. This compression allows the database to grow to approximately 1 PB when all tables are clustered columnstore (the default table type). Gen2: Unlimited storage for columnstore tables. Rowstore portion of the database is still limited to 240 TB compressed on disk.
Table	Max size	Unlimited size for columnstore tables. 60 TB for rowstore tables compressed on disk.
Table	Tables per database	100,000
Table	Columns per table	1024 columns
Table	Bytes per column	Dependent on column data type. Limit is 8000 for char data types, 4000 for nvarchar, or 2 GB for MAX data types.
Table	Bytes per row, defined size	8060 bytes The number of bytes per row is calculated in the same manner as it is for SQL Server with page compression. Like SQL Server, row-overflow storage is supported, which enables variable length columns to be pushed off-row. When variable length rows are pushed off-row, only 24-byte root is stored in the main record. For more information, see Row-Overflow Data Exceeding 8 KB.
Table	Partitions per table	15,000 For high performance, we recommend minimizing the number of partitions you need while still supporting your business requirements. As the number of partitions grows, the overhead for Data Definition Language (DDL) and Data Manipulation Language (DML) operations grows and causes slower performance.
Table	Characters per partition boundary value.	4000
Index	Non-clustered indexes per table.	50 Applies to rowstore tables only.
Index	Clustered indexes per table.	1 Applies to both rowstore and columnstore tables.
Index	Index key size.	900 bytes. Applies to rowstore indexes only. Indexes on varchar columns with a maximum size of more than 900 bytes can be created if the existing data in the columns does not exceed 900 bytes when the index is created. However, later INSERT or UPDATE actions on the columns that cause the total size to exceed 900 bytes will fail.
Index	Key columns per index.	16 Applies to rowstore indexes only. Clustered columnstore indexes include all columns.
Statistics	Size of the combined column values.	900 bytes.
Statistics	Columns per statistics object.	32
Statistics	Statistics created on columns per table.	30,000
Stored Procedures	Maximum levels of nesting.	8
View	Columns per view	1,024

Loads

Category	Description	Maximum
Polybase Loads	MB per row	1 Polybase loads rows that are smaller than 1 MB. Loading LOB data types into tables with a Clustered Columnstore Index (CCI) is not supported.
Polybase Loads	Total number of files	1,000,000 Polybase loads can not exceed more than 1M files. You may experience the following error: Operation failed as split count exceeding upper bound of 1000000.

Queries

Category	Description	Maximum
Query	Queued queries on user tables.	1000
Query	Concurrent queries on system views.	100
Query	Queued queries on system views	1000
Query	Maximum parameters	2098
Batch	Maximum size	65,536*4096
SELECT results	Columns per row	4096 You can never have more than 4096 columns per row in the SELECT result. There is no guarantee that you can always have 4096. If the query plan requires a temporary table, the 1024 columns per table maximum might apply.
SELECT	Nested subqueries	32 You can never have more than 32 nested subqueries in a SELECT statement. There is no guarantee that you can always have 32. For example, a JOIN can introduce a subquery into the query plan. The number of subqueries can also be limited by available memory.
SELECT	Columns per JOIN	1024 columns You can never have more than 1024 columns in the JOIN. There is no guarantee that you can always have 1024. If the JOIN plan requires a temporary table with more columns than the JOIN result, the 1024 limit applies to the temporary table.
SELECT	Bytes per GROUP BY columns.	8060 The columns in the GROUP BY clause can have a maximum of 8060 bytes.
SELECT	Bytes per ORDER BY columns	8060 bytes The columns in the ORDER BY clause can have a maximum of 8060 bytes
Identifiers per statement	Number of referenced identifiers	65,535 The number of identifiers that can be contained in a single expression of a query is limited. Exceeding this number results in SQL Server error 8632. For more information, see Internal error: An expression services limit has been reached.
String literals	Number of string literals in a statement	20,000 The number of string constants in a single expression of a query is limited. Exceeding this number results in SQL Server error 8632.

Metadata

DMV's will reset when a dedicated SQL pool is paused or when it is scaled.

System view	Maximum rows
sys.dm_pdw_dms_cores	100
sys.dm_pdw_dms_workers	Total number of DMS workers for the most recent 1000 SQL requests.
sys.dm_pdw_errors	10,000
sys.dm_pdw_exec_requests	10,000
sys.dm_pdw_exec_sessions	10,000
sys.dm_pdw_request_steps	Total number of steps for the most recent 1000 SQL requests that are stored in sys.dm_pdw_exec_requests.
sys.dm_pdw_sql_requests	The most recent 1000 SQL requests that are stored in sys.dm_pdw_exec_requests.

Next steps

For recommendations on using Azure Synapse, see the Cheat Sheet.