Starburst Synapse connector#

The Synapse connector allows you to query an external Azure Synapse SQL pool in Starburst Enterprise platform (SEP).

Requirements#

To connect to an Azure Synapse SQL pool, you need:

Configuration#

The connector can query a single Synapse SQL pool. Create a catalog properties file that specifies the Synapse connector by setting the connector.name to synapse.

For example, to access a Synapse SQL pool as mysynapsepool, create the file etc/catalog/mysynapsepool.properties. Replace the connection properties as appropriate for your setup:

connector.name=synapse
connection-url=jdbc:sqlserver://<serverName>:<portNumber>;database=<SQLpoolName>
connection-user=sepuser
connection-password=secret1v3

The connection-url parameter uses the SQL Server JDBC driver connection string syntax, from where the database parameter is inherited. This basic configuration can be used for both dedicated and serverless pools, as follows.

For dedicated SQL pools#

For this connection option:

  • The serverName component of the JDBC URL is shown in the Azure UI as the SQL endpoint in the following format: yourserver.sql.azuresynape.net.

  • For the database parameter, specify the name of the SQL pool that you create with DML such as CREATE SCHEMA synapse_pool.pool1.

Using the default port 1433, this results in a JDBC string like the following:

jdbc:sqlserver://yourserver.sql.azuresynapse.net:1433;database=pool1

For serverless SQL pools#

For this connection option:

  • The serverName component of the JDBC URL is found in the Azure UI as the SQL on-demand endpoint, in the following format: yourserver-ondemand.sql.azuresynapse.net.

  • For the database parameter, specify the fixed term master.

This results in a JDBC string like the following:

jdbc:sqlserver://yourserver-ondemand.sql.azuresynapse.net:1433;database=master

General configuration properties#

The following table describes general catalog configuration properties for the connector:

Property name

Description

Default value

case-insensitive-name-matching

Support case insensitive schema and table names.

false

case-insensitive-name-matching.cache-ttl

1m

case-insensitive-name-matching.config-file

Path to a name mapping configuration file in JSON format that allows Trino to disambiguate between schemas and tables with similar names in different cases.

null

case-insensitive-name-matching.refresh-period

Frequency with which Trino checks the name matching configuration file for changes.

0 (refresh disabled)

metadata.cache-ttl

Duration for which metadata, including table and column statistics, is cached.

0 (caching disabled)

metadata.cache-missing

Cache the fact that metadata, including table and column statistics, is not available

false

metadata.cache-maximum-size

Maximum number of objects stored in the metadata cache

10000

write.batch-size

Maximum number of statements in a batched execution. Do not change this setting from the default. Non-default values may negatively impact performance.

1000

join-pushdown.enabled

Enable join pushdown. Equivalent catalog session property is join_pushdown_enabled. Enabling this may negatively impact performance for some queries.

false

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)

CHAR(n)

NVARCHAR(n)

VARCHAR(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)

General configuration properties#

The following properties can be used to configure how data types from the connected data source are mapped to Trino data types and how the metadata is cached in Trino.

Property name

Description

Default value

unsupported-type-handling

Configure how unsupported column data types are handled:

  • IGNORE, column is not accessible.

  • CONVERT_TO_VARCHAR, column is converted to unbounded VARCHAR.

The respective catalog session property is unsupported_type_handling.

IGNORE

jdbc-types-mapped-to-varchar

Allow forced mapping of comma separated lists of data types to convert to unbounded VARCHAR

SQL support#

The connector provides read and write access to data and metadata in the Synapse SQL pool. In addition to the globally available and read operation statements, the connector supports the following features:

Warning

Transact-SQL syntax and associated features are not supported.

SQL DELETE#

If a WHERE clause is specified, the DELETE operation only works if the predicate in the clause can be fully pushed down to the data source.

Creating tables#

Synapse-native table structure and table distribution options for CREATE TABLE are not supported.

In addition, Synapse cannot create tables in serverless pools, which also applies to catalogs using Synapse in SEP.

ALTER TABLE#

The connector does not support renaming tables across multiple schemas. For example, the following statement is supported:

ALTER TABLE catalog.schema_one.table_one RENAME TO catalog.schema_one.table_two

The following statement attempts to rename a table across schemas, and therefore is not supported:

ALTER TABLE catalog.schema_one.table_one RENAME TO catalog.schema_two.table_two

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 to update such as 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:

Starburst Cached Views#

The connector 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.

Active Directory password authentication#

The connector supports Active Directory password authentication. To enable it, edit the catalog properties file to include the authentication type and specify user and password added to AD service associated with Synapse instance:

connection-user=active-directory-user
connection-password=active-directory-user-password
synapse.authentication.type=ACTIVE_DIRECTORY_PASSWORD

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.

Password credential pass-through#

The connector supports password credential pass-through. To enable it, edit the catalog properties file to include the authentication type:

synapse.authentication.type=PASSWORD_PASS_THROUGH

Use the ACTIVE_DIRECTORY_PASSWORD_PASS_THROUGH authentication type to enable password pass-through for Active Directory password authentication:

synapse.authentication.type=ACTIVE_DIRECTORY_PASSWORD_PASS_THROUGH

For more information about configurations and limitations, see Password credential pass-through.