This page provides a guide to Establishing a Connection to Apache Impala in CData Cloud, as well as information on the available resources, and a reference to the available connection properties.

Connecting to Apache Impala

Establishing a Connection shows how to authenticate to Apache Impala and configure any necessary connection properties to create a database in CData Cloud

Accessing Data from CData Cloud Services

Accessing data from Apache Impala through the available standard services and CData Cloud administration is documented in further details in the CData Cloud Documentation.

Connect to Apache Impala by selecting the corresponding icon in the Database tab. Required properties are listed under Settings. The Advanced tab lists connection properties that are not typically required.

Connecting to Apache Impala

In order to connect to Apache Impala, set the following:

• Server: The name or network address of the SQL Server instance.
• Port: The port for the connection to the Impala Server instance.
• ProtocolVersion: The Thrift protocol version to use when connecting to the Impala server.
• Database (optional): A default database to use when one is not supplied in the SQL query. This enables using table names without having to specify database.tablename in the query.
• Pagesize (optional): The number of results to pull per page from Apache Impala when selecting data.
• QueryPassthrough (optional): Indicates if the query should be passed to Impala as-is.
• UseSSL (optional): Set this to enable TLS/SSL.

  When QueryPassthrough is set to false (default), the CData ADO.NET Provider for Apache Impala will attempt to modify the query to conform to Impala required format.

Authenticating to Apache Impala

There are several ways to authenticate to Apache Impala including:

• NoSasl
• LDAP
• Kerberos

NoSasl

When using NoSasl, no authentication is performed. It is used when you are connecting to a server from a trusted location such as a test machine on your local network. By default, NoSasl is as the default AuthScheme, so no additional connection properties need to be set.

LDAP

To authenticate with LDAP, set the following connection properties:

• AuthScheme: Set this to LDAP.
• User: Set this to user to login as.
• Password: Set this to the password of the user.

To authenticate, set User, Password, and AuthScheme. If the LDAP server enables the Unauthenticated Authentication Mechanism of Simple Bind, the Password is optional instead of required.

Kerberos

Set the AuthScheme property to Kerberos. Please see Using Kerberos for details about how to authenticate with Kerberos.

Kerberos

To authenticate to Apache Impala with Kerberos, set AuthScheme to KERBEROS.

Authenticating to Apache Impala via Kerberos requires you to define authentication properties and to choose how Kerberos should retrieve authentication tickets.

Retrieve Kerberos Tickets

Kerberos tickets are used to authenticate the requester's identity. The use of tickets instead of formal logins/passwords eliminates the need to store passwords locally or send them over a network. Users are reauthenticated (tickets are refreshed) whenever they log in at their local computer or enter kinit USER at the command prompt.

The Cloud provides three ways to retrieve the required Kerberos ticket, depending on whether or not the KRB5CCNAME and/or KerberosKeytabFile variables exist in your environment.

MIT Kerberos Credential Cache File

This option enables you to use the MIT Kerberos Ticket Manager or kinit command to get tickets. With this option there is no need to set the User or Password connection properties.

This option requires that KRB5CCNAME has been created in your system.

To enable ticket retrieval via MIT Cerberos Credential Cache Files:

1. Ensure that the KRB5CCNAME variable is present in your environment.
2. Set KRB5CCNAME to a path that points to your credential cache file. (For example, C:\krb_cache\krb5cc_0 or /tmp/krb5cc_0.) The credential cache file is created when you use the MIT Kerberos Ticket Manager to generate your ticket.
3. To obtain a ticket:
   1. Open the MIT Kerberos Ticket Manager application.
   2. Click Get Ticket.
   3. Enter your principal name and password.
   4. Click OK.

   If the ticket is successfully obtained, the ticket information appears in Kerberos Ticket Manager and is stored in the credential cache file.

The Cloud uses the cache file to obtain the Kerberos ticket to connect to Apache Impala.

Note: If you would prefer not to edit KRB5CCNAME, you can use the KerberosTicketCache property to set the file path manually. After this is set, the Cloud uses the specified cache file to obtain the Kerberos ticket to connect to Apache Impala.

Keytab File

If your environment lacks the KRB5CCNAME environment variable, you can retrieve a Kerberos ticket using a Keytab File.

To use this method, set the User property to the desired username, and set the KerberosKeytabFile property to a file path pointing to the keytab file associated with the user.

User and Password

If your environment lacks the KRB5CCNAME environment variable and the KerberosKeytabFile property has not been set, you can retrieve a ticket using a user and password combination.

To use this method, set the User and Password properties to the user/password combination that you use to authenticate with Apache Impala.

Enabling Cross-Realm Authentication

More complex Kerberos environments can require cross-realm authentication where multiple realms and KDC servers are used. For example, they might use one realm/KDC for user authentication, and another realm/KDC for obtaining the service ticket.

To enable this kind of cross-realm authentication, set the KerberosRealm and KerberosKDC properties to the values required for user authentication. Also, set the KerberosServiceRealm and KerberosServiceKDC properties to the values required to obtain the service ticket.

Troubleshooting Performance

You may experience slow performance when querying large tables.

If you have a version of Apache Impala prior to version 3.4.0 installed, the following performance optimization is not possible. This is because these older versions are capped at a pagesize of 1024.

If you have Apache Impala version 3.4.0 or newer installed, follow this procedure to improve performance:

1. Set the Pagesize connection property to a comfortably high value. The default pagesize in versions 3.4.0 and later is 10000. A higher value will result in improved performance at the cost of addtional memory usage.
2. Enable result spooling by executing the following query:
   

   SET SPOOL_QUERY_RESULTS = TRUE

Customizing the SSL Configuration

By default, the Cloud attempts to negotiate SSL/TLS by checking the server's certificate against the system's trusted certificate store.

To specify another certificate, see the SSLServerCert property for the available formats to do so.

Connecting Through a Firewall or Proxy

HTTP Proxies

To connect through the Windows system proxy, you do not need to set any additional connection properties. To connect to other proxies, set ProxyAutoDetect to false.

In addition, to authenticate to an HTTP proxy, set ProxyAuthScheme, ProxyUser, and ProxyPassword, in addition to ProxyServer and ProxyPort.

Other Proxies

Set the following properties:

• To use a proxy-based firewall, set FirewallType, FirewallServer, and FirewallPort.
• To tunnel the connection, set FirewallType to TUNNEL.
• To authenticate, specify FirewallUser and FirewallPassword.
• To authenticate to a SOCKS proxy, additionally set FirewallType to SOCKS5.

The Cloud models Apache Impala instances as relational databases. The Cloud leverages the Impala Server Thrift API, to enable bidirectional access to Apache Impala data through SQL. Impala Server 2.2.0 and above are supported.

Discovering Schemas

The CData Cloud dynamically obtains the Apache Impala schemas. Reconnect to load any changes in the metadata, such as added or removed columns or changes in data type.

You can query the system tables described in this section to access schema information, information on data source functionality, and batch operation statistics.

Schema Tables

The following tables return database metadata for Apache Impala:

• sys_catalogs: Lists the available databases.
• sys_schemas: Lists the available schemas.
• sys_tables: Lists the available tables and views.
• sys_tablecolumns: Describes the columns of the available tables and views.
• sys_procedures: Describes the available stored procedures.
• sys_procedureparameters: Describes stored procedure parameters.
• sys_keycolumns: Describes the primary and foreign keys.
• sys_indexes: Describes the available indexes.

Data Source Tables

The following tables return information about how to connect to and query the data source:

• sys_connection_props: Returns information on the available connection properties.
• sys_sqlinfo: Describes the SELECT queries that the Cloud can offload to the data source.

Query Information Tables

The following table returns query statistics for data modification queries, including batch operations::

• sys_identity: Returns information about batch operations or single updates.

Lists the available databases.

The following query retrieves all databases determined by the connection string:

SELECT * FROM sys_catalogs

Columns

Name	Type	Description
CatalogName	String	The database name.

Lists the available schemas.

The following query retrieves all available schemas:

          SELECT * FROM sys_schemas
          

Columns

Name	Type	Description
CatalogName	String	The database name.
SchemaName	String	The schema name.

Lists the available tables.

The following query retrieves the available tables and views:

          SELECT * FROM sys_tables
          

Columns

Name	Type	Description
CatalogName	String	The database containing the table or view.
SchemaName	String	The schema containing the table or view.
TableName	String	The name of the table or view.
TableType	String	The table type (table or view).
Description	String	A description of the table or view.
IsUpdateable	Boolean	Whether the table can be updated.

Describes the columns of the available tables and views.

The following query returns the columns and data types for the [CData].[Default].Customers table:

SELECT ColumnName, DataTypeName FROM sys_tablecolumns WHERE TableName='Customers' AND CatalogName='CData' AND SchemaName='Default'

Columns

Name	Type	Description
CatalogName	String	The name of the database containing the table or view.
SchemaName	String	The schema containing the table or view.
TableName	String	The name of the table or view containing the column.
ColumnName	String	The column name.
DataTypeName	String	The data type name.
DataType	Int32	An integer indicating the data type. This value is determined at run time based on the environment.
Length	Int32	The storage size of the column.
DisplaySize	Int32	The designated column's normal maximum width in characters.
NumericPrecision	Int32	The maximum number of digits in numeric data. The column length in characters for character and date-time data.
NumericScale	Int32	The column scale or number of digits to the right of the decimal point.
IsNullable	Boolean	Whether the column can contain null.
Description	String	A brief description of the column.
Ordinal	Int32	The sequence number of the column.
IsAutoIncrement	String	Whether the column value is assigned in fixed increments.
IsGeneratedColumn	String	Whether the column is generated.
IsHidden	Boolean	Whether the column is hidden.
IsArray	Boolean	Whether the column is an array.
IsReadOnly	Boolean	Whether the column is read-only.
IsKey	Boolean	Indicates whether a field returned from sys_tablecolumns is the primary key of the table.

Lists the available stored procedures.

The following query retrieves the available stored procedures:

          SELECT * FROM sys_procedures
          

Columns

Name	Type	Description
CatalogName	String	The database containing the stored procedure.
SchemaName	String	The schema containing the stored procedure.
ProcedureName	String	The name of the stored procedure.
Description	String	A description of the stored procedure.
ProcedureType	String	The type of the procedure, such as PROCEDURE or FUNCTION.

Describes stored procedure parameters.

The following query returns information about all of the input parameters for the SearchSuppliers stored procedure:

SELECT * FROM sys_procedureparameters WHERE ProcedureName='SearchSuppliers' AND Direction=1 OR Direction=2

Columns

Name	Type	Description
CatalogName	String	The name of the database containing the stored procedure.
SchemaName	String	The name of the schema containing the stored procedure.
ProcedureName	String	The name of the stored procedure containing the parameter.
ColumnName	String	The name of the stored procedure parameter.
Direction	Int32	An integer corresponding to the type of the parameter: input (1), input/output (2), or output(4). input/output type parameters can be both input and output parameters.
DataTypeName	String	The name of the data type.
DataType	Int32	An integer indicating the data type. This value is determined at run time based on the environment.
Length	Int32	The number of characters allowed for character data. The number of digits allowed for numeric data.
NumericPrecision	Int32	The maximum precision for numeric data. The column length in characters for character and date-time data.
NumericScale	Int32	The number of digits to the right of the decimal point in numeric data.
IsNullable	Boolean	Whether the parameter can contain null.
IsRequired	Boolean	Whether the parameter is required for execution of the procedure.
IsArray	Boolean	Whether the parameter is an array.
Description	String	The description of the parameter.
Ordinal	Int32	The index of the parameter.

Describes the primary and foreign keys.

The following query retrieves the primary key for the [CData].[Default].Customers table:

         SELECT * FROM sys_keycolumns WHERE IsKey='True' AND TableName='Customers' AND CatalogName='CData' AND SchemaName='Default'
          

Columns

Name	Type	Description
CatalogName	String	The name of the database containing the key.
SchemaName	String	The name of the schema containing the key.
TableName	String	The name of the table containing the key.
ColumnName	String	The name of the key column.
IsKey	Boolean	Whether the column is a primary key in the table referenced in the TableName field.
IsForeignKey	Boolean	Whether the column is a foreign key referenced in the TableName field.
PrimaryKeyName	String	The name of the primary key.
ForeignKeyName	String	The name of the foreign key.
ReferencedCatalogName	String	The database containing the primary key.
ReferencedSchemaName	String	The schema containing the primary key.
ReferencedTableName	String	The table containing the primary key.
ReferencedColumnName	String	The column name of the primary key.

Describes the foreign keys.

The following query retrieves all foreign keys which refer to other tables:

         SELECT * FROM sys_foreignkeys WHERE ForeignKeyType = 'FOREIGNKEY_TYPE_IMPORT'
          

Columns

Name	Type	Description
CatalogName	String	The name of the database containing the key.
SchemaName	String	The name of the schema containing the key.
TableName	String	The name of the table containing the key.
ColumnName	String	The name of the key column.
PrimaryKeyName	String	The name of the primary key.
ForeignKeyName	String	The name of the foreign key.
ReferencedCatalogName	String	The database containing the primary key.
ReferencedSchemaName	String	The schema containing the primary key.
ReferencedTableName	String	The table containing the primary key.
ReferencedColumnName	String	The column name of the primary key.
ForeignKeyType	String	Designates whether the foreign key is an import (points to other tables) or export (referenced from other tables) key.

Describes the primary keys.

The following query retrieves the primary keys from all tables and views:

         SELECT * FROM sys_primarykeys
          

Columns

Name	Type	Description
CatalogName	String	The name of the database containing the key.
SchemaName	String	The name of the schema containing the key.
TableName	String	The name of the table containing the key.
ColumnName	String	The name of the key column.
KeySeq	String	The sequence number of the primary key.
KeyName	String	The name of the primary key.

Describes the available indexes. By filtering on indexes, you can write more selective queries with faster query response times.

The following query retrieves all indexes that are not primary keys:

          SELECT * FROM sys_indexes WHERE IsPrimary='false'
          

Columns

Name	Type	Description
CatalogName	String	The name of the database containing the index.
SchemaName	String	The name of the schema containing the index.
TableName	String	The name of the table containing the index.
IndexName	String	The index name.
ColumnName	String	The name of the column associated with the index.
IsUnique	Boolean	True if the index is unique. False otherwise.
IsPrimary	Boolean	True if the index is a primary key. False otherwise.
Type	Int16	An integer value corresponding to the index type: statistic (0), clustered (1), hashed (2), or other (3).
SortOrder	String	The sort order: A for ascending or D for descending.
OrdinalPosition	Int16	The sequence number of the column in the index.

Returns information on the available connection properties and those set in the connection string.

When querying this table, the config connection string should be used:

jdbc:cdata:apacheimpala:config:

This connection string enables you to query this table without a valid connection.

The following query retrieves all connection properties that have been set in the connection string or set through a default value:

SELECT * FROM sys_connection_props WHERE Value <> ''

Columns

Name	Type	Description
Name	String	The name of the connection property.
ShortDescription	String	A brief description.
Type	String	The data type of the connection property.
Default	String	The default value if one is not explicitly set.
Values	String	A comma-separated list of possible values. A validation error is thrown if another value is specified.
Value	String	The value you set or a preconfigured default.
Required	Boolean	Whether the property is required to connect.
Category	String	The category of the connection property.
IsSessionProperty	String	Whether the property is a session property, used to save information about the current connection.
Sensitivity	String	The sensitivity level of the property. This informs whether the property is obfuscated in logging and authentication forms.
PropertyName	String	A camel-cased truncated form of the connection property name.
Ordinal	Int32	The index of the parameter.
CatOrdinal	Int32	The index of the parameter category.
Hierarchy	String	Shows dependent properties associated that need to be set alongside this one.
Visible	Boolean	Informs whether the property is visible in the connection UI.
ETC	String	Various miscellaneous information about the property.

Describes the SELECT query processing that the Cloud can offload to the data source.

See SQL Compliance for SQL syntax details.

Discovering the Data Source's SELECT Capabilities

Below is an example data set of SQL capabilities. Some aspects of SELECT functionality are returned in a comma-separated list if supported; otherwise, the column contains NO.

Name	Description	Possible Values
AGGREGATE_FUNCTIONS	Supported aggregation functions.	AVG, COUNT, MAX, MIN, SUM, DISTINCT
COUNT	Whether COUNT function is supported.	YES, NO
IDENTIFIER_QUOTE_OPEN_CHAR	The opening character used to escape an identifier.	[
IDENTIFIER_QUOTE_CLOSE_CHAR	The closing character used to escape an identifier.	]
SUPPORTED_OPERATORS	A list of supported SQL operators.	=, >, <, >=, <=, <>, !=, LIKE, NOT LIKE, IN, NOT IN, IS NULL, IS NOT NULL, AND, OR
GROUP_BY	Whether GROUP BY is supported, and, if so, the degree of support.	NO, NO_RELATION, EQUALS_SELECT, SQL_GB_COLLATE
OJ_CAPABILITIES	The supported varieties of outer joins supported.	NO, LEFT, RIGHT, FULL, INNER, NOT_ORDERED, ALL_COMPARISON_OPS
OUTER_JOINS	Whether outer joins are supported.	YES, NO
SUBQUERIES	Whether subqueries are supported, and, if so, the degree of support.	NO, COMPARISON, EXISTS, IN, CORRELATED_SUBQUERIES, QUANTIFIED
STRING_FUNCTIONS	Supported string functions.	LENGTH, CHAR, LOCATE, REPLACE, SUBSTRING, RTRIM, LTRIM, RIGHT, LEFT, UCASE, SPACE, SOUNDEX, LCASE, CONCAT, ASCII, REPEAT, OCTET, BIT, POSITION, INSERT, TRIM, UPPER, REGEXP, LOWER, DIFFERENCE, CHARACTER, SUBSTR, STR, REVERSE, PLAN, UUIDTOSTR, TRANSLATE, TRAILING, TO, STUFF, STRTOUUID, STRING, SPLIT, SORTKEY, SIMILAR, REPLICATE, PATINDEX, LPAD, LEN, LEADING, KEY, INSTR, INSERTSTR, HTML, GRAPHICAL, CONVERT, COLLATION, CHARINDEX, BYTE
NUMERIC_FUNCTIONS	Supported numeric functions.	ABS, ACOS, ASIN, ATAN, ATAN2, CEILING, COS, COT, EXP, FLOOR, LOG, MOD, SIGN, SIN, SQRT, TAN, PI, RAND, DEGREES, LOG10, POWER, RADIANS, ROUND, TRUNCATE
TIMEDATE_FUNCTIONS	Supported date/time functions.	NOW, CURDATE, DAYOFMONTH, DAYOFWEEK, DAYOFYEAR, MONTH, QUARTER, WEEK, YEAR, CURTIME, HOUR, MINUTE, SECOND, TIMESTAMPADD, TIMESTAMPDIFF, DAYNAME, MONTHNAME, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, EXTRACT
REPLICATION_SKIP_TABLES	Indicates tables skipped during replication.
REPLICATION_TIMECHECK_COLUMNS	A string array containing a list of columns which will be used to check for (in the given order) to use as a modified column during replication.
IDENTIFIER_PATTERN	String value indicating what string is valid for an identifier.
SUPPORT_TRANSACTION	Indicates if the provider supports transactions such as commit and rollback.	YES, NO
DIALECT	Indicates the SQL dialect to use.
KEY_PROPERTIES	Indicates the properties which identify the uniform database.
SUPPORTS_MULTIPLE_SCHEMAS	Indicates if multiple schemas may exist for the provider.	YES, NO
SUPPORTS_MULTIPLE_CATALOGS	Indicates if multiple catalogs may exist for the provider.	YES, NO
DATASYNCVERSION	The CData Data Sync version needed to access this driver.	Standard, Starter, Professional, Enterprise
DATASYNCCATEGORY	The CData Data Sync category of this driver.	Source, Destination, Cloud Destination
SUPPORTSENHANCEDSQL	Whether enhanced SQL functionality beyond what is offered by the API is supported.	TRUE, FALSE
SUPPORTS_BATCH_OPERATIONS	Whether batch operations are supported.	YES, NO
SQL_CAP	All supported SQL capabilities for this driver.	SELECT, INSERT, DELETE, UPDATE, TRANSACTIONS, ORDERBY, OAUTH, ASSIGNEDID, LIMIT, LIKE, BULKINSERT, COUNT, BULKDELETE, BULKUPDATE, GROUPBY, HAVING, AGGS, OFFSET, REPLICATE, COUNTDISTINCT, JOINS, DROP, CREATE, DISTINCT, INNERJOINS, SUBQUERIES, ALTER, MULTIPLESCHEMAS, GROUPBYNORELATION, OUTERJOINS, UNIONALL, UNION, UPSERT, GETDELETED, CROSSJOINS, GROUPBYCOLLATE, MULTIPLECATS, FULLOUTERJOIN, MERGE, JSONEXTRACT, BULKUPSERT, SUM, SUBQUERIESFULL, MIN, MAX, JOINSFULL, XMLEXTRACT, AVG, MULTISTATEMENTS, FOREIGNKEYS, CASE, LEFTJOINS, COMMAJOINS, WITH, LITERALS, RENAME, NESTEDTABLES, EXECUTE, BATCH, BASIC, INDEX
PREFERRED_CACHE_OPTIONS	A string value specifies the preferred cacheOptions.
ENABLE_EF_ADVANCED_QUERY	Indicates if the driver directly supports advanced queries coming from Entity Framework. If not, queries will be handled client side.	YES, NO
PSEUDO_COLUMNS	A string array indicating the available pseudo columns.
MERGE_ALWAYS	If the value is true, The Merge Mode is forcibly executed in Data Sync.	TRUE, FALSE
REPLICATION_MIN_DATE_QUERY	A select query to return the replicate start datetime.
REPLICATION_MIN_FUNCTION	Allows a provider to specify the formula name to use for executing a server side min.
REPLICATION_START_DATE	Allows a provider to specify a replicate startdate.
REPLICATION_MAX_DATE_QUERY	A select query to return the replicate end datetime.
REPLICATION_MAX_FUNCTION	Allows a provider to specify the formula name to use for executing a server side max.
IGNORE_INTERVALS_ON_INITIAL_REPLICATE	A list of tables which will skip dividing the replicate into chunks on the initial replicate.
CHECKCACHE_USE_PARENTID	Indicates whether the CheckCache statement should be done against the parent key column.	TRUE, FALSE
CREATE_SCHEMA_PROCEDURES	Indicates stored procedures that can be used for generating schema files.

The following query retrieves the operators that can be used in the WHERE clause:

SELECT * FROM sys_sqlinfo WHERE Name = 'SUPPORTED_OPERATORS'

Note that individual tables may have different limitations or requirements on the WHERE clause; refer to the Data Model section for more information.

Columns

Name	Type	Description
NAME	String	A component of SQL syntax, or a capability that can be processed on the server.
VALUE	String	Detail on the supported SQL or SQL syntax.

Returns information about attempted modifications.

The following query retrieves the Ids of the modified rows in a batch operation:

         SELECT * FROM sys_identity
          

Columns

Name	Type	Description
Id	String	The database-generated Id returned from a data modification operation.
Batch	String	An identifier for the batch. 1 for a single operation.
Operation	String	The result of the operation in the batch: INSERTED, UPDATED, or DELETED.
Message	String	SUCCESS or an error message if the update in the batch failed.

The connection string properties are the various options that can be used to establish a connection. This section provides a complete list of the options you can configure in the connection string for this provider. Click the links for further details.

For more information on establishing a connection, see Establishing a Connection.

Authentication

---

Property	Description
AuthScheme	The authentication scheme used. Accepted values are NoSasl, LDAP and Kerberos.
Server	The name of the server running SQL Server.
Port	The port for the connection to the Impala Server instance.
User	The username used to authenticate with Impala.
Password	The password used to authenticate with Impala.
ProtocolVersion	The Thrift protocol version to use when connecting to the Impala server.
Database	The name of the Impala database to use by default.
TransportMode	The transport mode to use to communicate with the Impala server. Accepted entries are BINARY and HTTP.

SSL

---

Property	Description
SSLServerCert	The certificate to be accepted from the server when connecting using TLS/SSL.

Logging

---

Property	Description
Verbosity	The verbosity level that determines the amount of detail included in the log file.

Schema

---

Property	Description
BrowsableSchemas	This property restricts the schemas reported to a subset of the available schemas. For example, BrowsableSchemas=SchemaA,SchemaB,SchemaC.

Miscellaneous

---

Property	Description
HTTPPath	The path component of the URL endpoint when using HTTP TransportMode.
MaxRows	Limits the number of rows returned when no aggregation or GROUP BY is used in the query. This takes precedence over LIMIT clauses.
Pagesize	The maximum number of results to return per page from Apache Impala.
PseudoColumns	This property indicates whether or not to include pseudo columns as columns to the table.
Timeout	The value in seconds until the timeout error is thrown, canceling the operation.
UseSSL	Specifies whether to use SSL Encryption when connecting to Impala.

This section provides a complete list of the Authentication properties you can configure in the connection string for this provider.

---

Property	Description
AuthScheme	The authentication scheme used. Accepted values are NoSasl, LDAP and Kerberos.
Server	The name of the server running SQL Server.
Port	The port for the connection to the Impala Server instance.
User	The username used to authenticate with Impala.
Password	The password used to authenticate with Impala.
ProtocolVersion	The Thrift protocol version to use when connecting to the Impala server.
Database	The name of the Impala database to use by default.
TransportMode	The transport mode to use to communicate with the Impala server. Accepted entries are BINARY and HTTP.

The authentication scheme used. Accepted values are NoSasl, LDAP and Kerberos.

Possible Values

LDAP

Data Type

string

Default Value

"LDAP"

Remarks

The AuthScheme used to authenticate with Impala.

NoSasl (default)	default
LDAP	Used when the enable_ldap_auth property is set to true and ldap_uri property is not empty.
Kerberos	Used when the keytab_file property is is not empty.

The name of the server running SQL Server.

Data Type

string

Default Value

""

Remarks

Set this property to the name or network address of the SQL Server instance.

The port for the connection to the Impala Server instance.

Data Type

string

Default Value

"21050"

Remarks

When using BINARY TransportMode, this property should be set to the value in the 'hs2_port'(default 21050) property of the impala configuration (http://host:25000/varz).

When using HTTP TransportMode, this property should be set to the value in the 'hs2_http_port'(default 28000) property of the impala configuration (http://host:25000/varz).

The username used to authenticate with Impala.

Data Type

string

Default Value

""

Remarks

The username used to authenticate with Impala.

The password used to authenticate with Impala.

Data Type

string

Default Value

""

Remarks

The password used to authenticate with Impala.

The Thrift protocol version to use when connecting to the Impala server.

Possible Values

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11

Data Type

string

Default Value

"7"

Remarks

The most efficient protocol version will be determined automatically by the CData Cloud upon connecting to Impala. This property allows you to explicitly specify the version to use and overrides the version determined by the CData Cloud.

The name of the Impala database to use by default.

Data Type

string

Default Value

""

Remarks

When specified, the CData Cloud will issue a 'USE [Database]' command upon connecting to Impala. This will be the database schema used when executing queries that do not have a schema explicitly specified.

To execute queries on other schemas, the schema can be explicitly specified in the statement.

When Database is not set, the 'default' database schema will be used (no 'USE' statement is issued to Impala in this case).

The transport mode to use to communicate with the Impala server. Accepted entries are BINARY and HTTP.

Possible Values

BINARY, HTTP

Data Type

string

Default Value

"BINARY"

Remarks

The transport mode used to communicate with the Impala server.

This section provides a complete list of the SSL properties you can configure in the connection string for this provider.

---

Property	Description
SSLServerCert	The certificate to be accepted from the server when connecting using TLS/SSL.

The certificate to be accepted from the server when connecting using TLS/SSL.

Data Type

string

Default Value

""

Remarks

If using a TLS/SSL connection, this property can be used to specify the TLS/SSL certificate to be accepted from the server. Any other certificate that is not trusted by the machine is rejected.

This property can take the following forms:

Description	Example
A full PEM Certificate (example shortened for brevity)	-----BEGIN CERTIFICATE----- MIIChTCCAe4CAQAwDQYJKoZIhv......Qw== -----END CERTIFICATE-----
A path to a local file containing the certificate	C:\cert.cer
The public key (example shortened for brevity)	-----BEGIN RSA PUBLIC KEY----- MIGfMA0GCSq......AQAB -----END RSA PUBLIC KEY-----
The MD5 Thumbprint (hex values can also be either space or colon separated)	ecadbdda5a1529c58a1e9e09828d70e4
The SHA1 Thumbprint (hex values can also be either space or colon separated)	34a929226ae0819f2ec14b4a3d904f801cbb150d

If not specified, any certificate trusted by the machine is accepted.

Use '*' to signify to accept all certificates. Note that this is not recommended due to security concerns.

This section provides a complete list of the Logging properties you can configure in the connection string for this provider.

---

Property	Description
Verbosity	The verbosity level that determines the amount of detail included in the log file.

The verbosity level that determines the amount of detail included in the log file.

Data Type

string

Default Value

"1"

Remarks

The verbosity level determines the amount of detail that the Cloud reports to the Logfile. Verbosity levels from 1 to 5 are supported. These are detailed in the Logging page.

This section provides a complete list of the Schema properties you can configure in the connection string for this provider.

---

Property	Description
BrowsableSchemas	This property restricts the schemas reported to a subset of the available schemas. For example, BrowsableSchemas=SchemaA,SchemaB,SchemaC.

This property restricts the schemas reported to a subset of the available schemas. For example, BrowsableSchemas=SchemaA,SchemaB,SchemaC.

Data Type

string

Default Value

""

Remarks

Listing the schemas from databases can be expensive. Providing a list of schemas in the connection string improves the performance.

This section provides a complete list of the Miscellaneous properties you can configure in the connection string for this provider.

---

Property	Description
HTTPPath	The path component of the URL endpoint when using HTTP TransportMode.
MaxRows	Limits the number of rows returned when no aggregation or GROUP BY is used in the query. This takes precedence over LIMIT clauses.
Pagesize	The maximum number of results to return per page from Apache Impala.
PseudoColumns	This property indicates whether or not to include pseudo columns as columns to the table.
Timeout	The value in seconds until the timeout error is thrown, canceling the operation.
UseSSL	Specifies whether to use SSL Encryption when connecting to Impala.

The path component of the URL endpoint when using HTTP TransportMode.

Data Type

string

Default Value

"cliservice"

Remarks

This property is used to specify the path component of the URL endpoint when using HTTP TransportMode.

Limits the number of rows returned when no aggregation or GROUP BY is used in the query. This takes precedence over LIMIT clauses.

Data Type

int

Default Value

-1

Remarks

Limits the number of rows returned when no aggregation or GROUP BY is used in the query. This takes precedence over LIMIT clauses.

The maximum number of results to return per page from Apache Impala.

Data Type

int

Default Value

10000

Remarks

The Pagesize property affects the maximum number of results to return per page from Apache Impala. Setting a higher value may result in better performance at the cost of additional memory allocated per page consumed.

This property indicates whether or not to include pseudo columns as columns to the table.

Data Type

string

Default Value

""

Remarks

This setting is particularly helpful in Entity Framework, which does not allow you to set a value for a pseudo column unless it is a table column. The value of this connection setting is of the format "Table1=Column1, Table1=Column2, Table2=Column3". You can use the "*" character to include all tables and all columns; for example, "*=*".

The value in seconds until the timeout error is thrown, canceling the operation.

Data Type

int

Default Value

60

Remarks

If Timeout = 0, operations do not time out. The operations run until they complete successfully or until they encounter an error condition.

If Timeout expires and the operation is not yet complete, the Cloud throws an exception.

Specifies whether to use SSL Encryption when connecting to Impala.

Data Type

bool

Default Value

false

Remarks

Specifies whether to use SSL Encryption when connecting to Impala.

Apache Thrift Client

The Apache License Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.