Starburst Synapse connector#

The Synapse connector allows querying an external Azure Synapse SQL database in Starburst Enterprise platform (SEP).

Note

The connector requires a valid Starburst Enterprise license.

Configuration#

The connector can query a single database on a single instance of Synapse. Create a catalog properties file that specifies the Synapse connector by setting the connector.name to synapse.

For example, to access a database as mysynapsedb, create the file etc/catalog/mysynapsedb.properties. Replace the connection properties as appropriate for your setup:

connector.name=synapse
connection-url=jdbc:sqlserver://<host>:<port>;database=<database>
connection-user=root
connection-password=secret

This basic configuration can be used for both dedicated and serverless pools. The connection URL parameter uses the SQL Server JDBC driver connection string syntax.

Type mapping#

Because SEP and Synapse each support types that the other does not, this connector modifies some types when reading or writing data.

Synapse to SEP read type mapping#

The following read type mapping applies when data is read from existing tables in Synapse, or inserted into existing tables in Synapse from SEP.

Synapse to SEP read type mapping#

Synapse type

SEP type

Notes

BIT

BOOLEAN

BIGINT

BIGINT

SMALLINT

SMALLINT

TINYINT

TINYINT

INT

INTEGER

DECIMAL(p, s), ``NUMERIC(p, s)

DECIMAL(p, s)

for p <= 38

DOUBLE PRECISION

DOUBLE

FLOAT

DOUBLE

BINARY

VARBINARY

CHAR(n)

CHAR(n)

VARCHAR(n)

VARCHAR(n)

NCHAR(n)

NCHAR(n)

NVARCHAR(n)

NVARCHAR(n)

DATE

DATE

DATETIME2(n)

TIMESTAMP(n)

TIME

TIME

No other types are supported.

SEP to Synapse write type mapping#

The following write type mapping applies when tables are created in Synapse from SEP.

SEP to Synapse write type mapping#

SEP type

Synapse type

Notes

BOOLEAN

BIT

BIGINT

BIGINT

INTEGER

INT

SMALLINT

SMALLINT

DOUBLE

DOUBLE PRECISION

CHAR(n <= 4000)

NCHAR(n)

VARCHAR(n <= 4000)

NVARCHAR(n)

VARBINARY

VARBINARY(8000)

DATE

DATE

TIME

TIME

TIMESTAMP(n <= 7) without time zone

DATETIME2(n)

TIMESTAMP(n > 7) without time zone

DATETIME2(7)

Performance#

The connector includes a number of performance-enhancing features, detailed in the following sections.

Table statistics#

The Synapse SQL connector supports table and column statistics to improve query processing performance based on the actual data in the data source.

Table statistics are enabled by default in Synapse SQL.

The connector can retrieve and use information stored in single-column statistics. Synapse can automatically create column statistics for certain columns. If column statistics were not created automatically for a certain column, you can create them by executing the following statement in Synapse SQL:

CREATE STATISTICS my_statistics_name ON table_schema.table_name (column_name);

Synapse SQL routinely updates the statistics as long as the AUTO_CREATE_STATISTICS option is set to ON in Synapse SQL. In some cases, you may want to force statistics update (e.g. after defining new column statistics or after changing data in the table). You can do that by executing the following statement in Synapse SQL:

UPDATE STATISTICS table_schema.table_name(stat_name);

Dynamic filtering#

Dynamic filtering is enabled by default. It causes the connector to wait for dynamic filtering to complete before starting a JDBC query.

You can disable dynamic filtering by setting the property dynamic-filtering.enabled in your catalog properties file to false.

Pushdown#

The connector supports pushdown for a number of operations:

Aggregate pushdown for the following functions:

Caching table projections#

The connectors supports table scan redirection to improve performance and reduce load on the data source.

Security#

The connector includes a number of security-related features, detailed in the following sections.

User impersonation#

The Synapse SQL connector supports user impersonation.

User impersonation can be enabled in the catalog file:

synapse.impersonation.enabled=true

User impersonation in the Synapse connector is based on EXECUTE AS USER.

Limitations#

The connector has the following limitations:

  • Table structure and table distribution options for CREATE TABLE are not supported.

  • TIMESTAMP is not supported; use DATETIME2 instead. Note that SEP translates DATETIME2 to TIMESTAMP in SELECT result sets.

  • Synapse limits certain functionality and features when using serverless pools.

Refer to the Synapse SQL documentation for information about options, limitations and additional considerations.