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Amazon Redshift

Amazon Redshift is a data warehouse that allows its users to analyze data in conjunction with existing Business Intelligence tools and standard SQL. With Amazon Redshift users are enabled to perform complex analysis queries on multiple petabytes of structured data.

Type Name

redshift

Connection Properties

Template name: redshift

Appropriate translator name: redshift

Properties:

  • host (default: localhost)
  • port (default: 5439)
  • db
  • user-name
  • password (default: empty)
  • driver (default: redshift)
  • driver-class (default: com.amazon.redshift.jdbc.Driver)
  • ssl (TRUE|FALSE; default: FALSE)
  • jdbc-properties (arbitrary extra properties)

  • new-connection-sql

  • check-valid-connection-sql (default: select 0)
  • min-pool-size (default: 2)
  • max-pool-size (default: 70)
  • cloudAgent (default: FALSE)


Here is an example:

SQL 
CALL SYSADMIN.createConnection(name => 'redshift', jbossCLITemplateName => 'redshift', connectionOrResourceAdapterProperties => 'host=<host>,port=5439,db=<database>,user-name=<user_name>,password=<password>') ;;
CALL SYSADMIN.createDataSource(name => 'redshift', translator => 'redshift', modelProperties => 'importer.schemaPattern=test_nk,importer.useFullSchemaName=FALSE,importer.tableTypes="TABLE,VIEW"', translatorProperties => 'supportsNativeQueries=true') ;;

Translator Properies

Translator Properties Shared by All JDBC Connectors

(Properties listed in alphabetical order)

To view the full table, click the expand button in its top right corner


Name

Description

Default value

comparisonStringConversion

Sets a template to convert WHERE clauses on strings

Examples

SQL 
comparisonStringConversion=%s
-- no conversion will be applied

comparisonStringConversion=binary %s
-- WHERE binary someStringExpression LIKE someOtherStringExpression

comparisonStringConversion=(%s COLLATE Latin1_General_CS_AS)
-- WHERE (someStringExpression COLLATE Latin1_General_CS_AS LIKE someOtherStringExpression)


  • MS SQL Server:
    (%s COLLATE Latin1_General_CS_AS)
  • MySQL, SingleStore:
    binary %s
  • Others:
    %s

DatabaseTimeZone

Database time zone, used when fetching date, time, or timestamp values

System default time zone

DatabaseVersion

Specific database version, used to fine-tune pushdown support

Automatically detected by the server through the data source JDBC driver, if possible

forbidNonMatchingNamesOnly considered when importer.tableNamePattern is set. When set to FALSE, allows creation of tables with names that do not match the tableNamePattern. Tables with non-matching names will only be accessible until the server restartsTRUE
ForceQuotedIdentifiers

If TRUE, all identifiers in the final query (that is being generated by a translator to be sent directly to the target DBMS) will be quoted

TRUE

MaxPreparedInsertBatchSize

Maximum size of prepared insert batch

2048

OrderByStringConversion

Sets a template to convert ORDER BY clauses on strings

Examples

SQL 
OrderByStringConversion=%s
-- no conversion will be applied

OrderByStringConversion=(binary %s)
-- ORDER BY (binary someStringExpression)

OrderByStringConversion=cast((%s) as varchar(2000) ccsid 1208)
-- ORDER BY cast((someStringExpression) as varchar(2000) ccsid 1208)
  • DB2 for AS/400:
    cast((%s) as varchar(2000) ccsid 1208)
  • DB2 for zOS:
    cast((%s) as varchar(2000) ccsid ASCII)
  • MS SQL Server:
    (cast(cast(%s as varchar) as varbinary)
  • MySQL, SingleStore:
    (binary %s)
  • PostgreSQL:
    (%s COLLATE \"C\")
  • Others:
    %s
supportsConvertFromClobToString If TRUE, indicates that the translator supports the CONVERT/CAST function from clob to string
  • MySQL, PostgreSQL, Redshift, Greenplum, Oracle, MS SQL Server:
    TRUE 
  • Others:
    FALSE

supportsNativeQueries

Forces a translator to issue a native() system procedure that can be used to pass native queries directly to an underlying DBMS

Example

SQL 
SELECT x.* 
FROM table
  ( 
    CALL "dwh.native"("request" => 'SELECT query, pid, elapsed, substring FROM svl_qlog ORDER BY STARTTIME DESC LIMIT 200') 
  ) w
  , ARRAYTABLE( w.tuple COLUMNS query string, pid integer , elapsed string, "substring" string ) x;

More usage examples

  • MySQL, PostgreSQL, Redshift, Snowflake, Oracle, MS SQL Server; Exasol, Vertica, Bigquery, SingleStore, Azure:
    TRUE
  • Others:
    FALSE
supportsOrderByAlias

If FALSE, the CData Virtuality Server does not generate aliases in the ORDER BY clause.

If TRUE, indicates that the source supports aliases in the ORDER BY clause

  • PostgreSQL:
    TRUE
  • Others:
    • if OrderByStringConversion is not set, same as supportsOrderBy
    • if OrderByStringConversion is set, default for supportsOrderByAlias is  FALSE
supportsOrderByString

If FALSE, the CData Virtuality Server does not push down the ORDER BY clause if it contains at least one expression of string type.

If TRUE, indicates that the source supports strings in the ORDER BY clause

TrimStrings

If TRUE, trims trailing whitespace from fixed-length character strings. Please note that the CData Virtuality Server only has string or varchar type that treats trailing whitespace as meaningful

FALSE

UseBindVariables

if TRUE, indicates that PreparedStatements should be used and that literal values in the source query should be replaced with bind variables. If FALSE, only LOB values will trigger the use of PreparedStatements

TRUE

UseCommentsInSourceQuery

Embeds a / comment / leading comment with session/request id in the source SQL query for informational purposes

FALSE

The names of the translator properties are case-sensitive.

Translator Properties Specific for Amazon Redshift

To view the full table, click the expand button in its top right corner


NameDescriptionDefault value
replaceNullCharsWithString property. If set, the translator replaces all null characters in strings before executing INSERT / UPDATE with the string specified as the property value. You may specify an empty string as wellSingle space
uploadMode

Values: bulkInsertSingleThread, bulkInsertMultiThread

  • bulkInsertSingleThread: Bulk inserts in a single thread
  • bulkInsertMultiThread: Bulk inserts in multiple threads

The legacy value insertMultiThread still works for backward compatibility


Value: s3Load

Uploads data as files on Amazon S3 storage. Translator properties region, keyId, and secretKey should be specified for the mode to work properly.

The value is case-insensitive, so s3Load and S3LOAD are the same values


maxChunkSizeSets the size limit of a temp file in bytes 16000
numberOfThreadsSpecifies the maximum number of uploader threads 10
tempFolder

Value: a path to a folder (relative or absolute).

Specifies the folder to be used for creating temporary files instead of the system configured one. If not specified, the default OS tmp folder is used
bucketName

Value: a bucket name.

Only for the s3Load uploadMode.
Specifies a bucket name to upload data files to. If specified, the specified bucket is used and assumed to exist (no creation/deletion operations performed). The region specified for the bucket must be the same as the region specified via the region translator property. If no bucketName is specified, a bucket will be created and deleted after the operation is finished
bucketPrefix

Value: a bucket prefix.

Only for the s3Load uploadMode.
Specifies a prefix of a bucket name to upload data files to. The name of the bucket created for uploading will start with the specified prefix. The bucket will be deleted after the operation is finished
createBucket

Value: boolean.

Specifies if the bucket set by the bucketName property should be created if it does not exist

 FALSE
region

Value: a region.

Only for the s3Load uploadMode.
Specifies a region endpoint
keyId, secretKey

Only for the s3Load uploadMode. You can read and set the values for keyId and secretKey via the AWS console -> S3 -> username in the upper right corner -> Security Credentials -> Access Keys (Access Key ID and Secret Access Key)
iamRole, awsAccountId

Only for the s3Load uploadMode. Alternate (to keyId and secretKey) way to perform S3 authorization
EncryptDataOnS3

Only for the s3Load uploadMode. Indicates whether the uploaded file should be encrypted

 FALSE
useDoubleSlashToEscapeRegex

Used to change the default escaping behaviour in LIKE_REGEX expressions

 TRUE
uploadZipped

Enables compression of temporary files before uploading them to S3. May be disabled for environments with high network bandwidth in order to save some CPU power but this will increase the disk usage

 FALSE
truncateStrings

If FALSE, an exception is thrown if a string/clob value exceeds storage size. Otherwise, if set to TRUE, values that exceed storage size will be truncated

 FALSE
varcharReserveAdditionalSpacePercent

As Redshift and Vertica measure varchar size in bytes, not chars, and stores strings in UTF-8 encoding, a char may be 1 to 4 bytes long. You can specify the percentage by which the byte size will exceed the original char size.
For instance, if in an original DBMS there is a varchar(32) column (32 chars), the actual data of 32 chars long may occupy 32 bytes for English alphabet or 128 bytes for Chinese characters. If the user knows that the data contain English chars only, he may not specify it at all and the resulting column in the target will be varchar(32) (bytes this time). If the user uses the Chinese language for the column, he should specify a value of 300 for the property and it means that it is necessary to add 300 percent to the original field length (32 + 300 % = 128).

Also, there's a special value: 65535 which makes every varchar to be of 65535 bytes long

 0
acceptInvChars

Value:  any ASCII character except NULL

Only for the s3Load uploadMode.

This property enables the loading of data into VARCHAR columns even if the data contains invalid UTF-8 characters. If it's specified, ACCEPTINVCHARS option will be passed to the S3 COPY command and each invalid UTF-8 character will be replaced with a string of equal length consisting of the character specified. For example, if the replacement character is '^', an invalid three-bytruncateStringste character will be replaced with '^^^'.

If acceptInvChars is not specified, an error will be thrown whenever an invalid UTF-8 character is encountered
copyParams

Arbitrary parameters to be passed to the COPY command when uploading data from S3

 NULL
keepTempFiles

Keep temporary files after uploading

 FALSE - can be enabled for debugging
maxTableNameLength

Maximum length of a table name

 127
maxColumnNameLength

Maximum length of a column name .

(info) Five chars of defined maximum length will be reserved for internal purposes and cannot be used for column-identifier

 127

Here is an example:

SQL 
CALL SYSADMIN.createConnection(name => 'redshift', jbossCLITemplateName => 'redshift', connectionOrResourceAdapterProperties => 'host=<host>,port=5439,db=<database>,user-name=<user_name>,password=<password>') ;;
CALL SYSADMIN.createDataSource(name => 'redshift', translator => 'redshift', modelProperties => 'importer.schemaPattern=test_nk,importer.useFullSchemaName=FALSE,importer.tableTypes="TABLE,VIEW"', translatorProperties => 'varcharReserveAdditionalSpacePercent=300,supportsNativeQueries=true,uploadMode=s3Load,region=<region>,bucketName=<bucket_name>,createBucket=true,keyId=<key_ID>,secretKey="<secret_key>"') ;;

Translator Properties for Amazon Redshift as Analytical Storage

If Amazon Redshift is used as analytical storage, we recommend loading data using Amazon AWS S3 (S3LOAD), as inserting data into Redshift using standard JDBC protocol can be very slow.

The following translator properties are required to configure S3LOAD:

ParameterDescription
uploadMode=s3loadExplicitly specifies S3LOAD mode

region

AWS S3 region endpoint
bucketNameBucket name to upload data files t; optional
bucketPrefixPrefix of the temporary bucket to upload data files to if bucketName is not specified; must comply with Amazon S3 bucket naming convention (nb: 36 characters would be added to the bucket prefix when creating a temporary bucket); optional
createBucketSpecifies if the bucket set in the bucketName parameter should be created if it does not exist; optional; default: FALSE
keyIdAWS S3 key ID
secretKeyAWS S3 secret key

Here is an example:

SQL 
CALL SYSADMIN.createConnection(name => 'redshift', jbossCLITemplateName => 'redshift', connectionOrResourceAdapterProperties => 'host=<host>,port=5439,db=<database>,user-name=<user_name>,password=<password>') ;;
CALL SYSADMIN.createDataSource(name => 'redshift', translator => 'redshift', modelProperties => 'importer.schemaPattern=test_nk,importer.useFullSchemaName=FALSE,importer.tableTypes="TABLE,VIEW"', translatorProperties => 'varcharReserveAdditionalSpacePercent=300,supportsNativeQueries=true,uploadMode=s3Load,region=<region>,bucketName=<bucket_name>,createBucket=true,keyId=<key_ID>,secretKey="<secret_key>"') ;;

Data Source Properties

Data Source Properties Shared by All JDBC Connectors

(Properties listed in alphabetical order)

To view the full table, click the expand button in its top right corner


Name

Description

Default

importer.autoCorrectColumnNames Replaces . in a column name with _ as the period character is not supported by the CData Virtuality Server in column names TRUE
importer.catalog

Database catalogs to use. Can be used if the db connection property is omitted.

Only for Microsoft SQL Server and Snowflake:

  • Multiple catalogs (multiple databases) usage is supported;
  • '%' as a wildcard is allowed: for example, importer.catalog="foo%" will import foo, foobar, etc.
  • To specify several catalog names or/and patterns, values should be comma-separated and enclosed within double quotes: importer.catalog="schema1,schema2,pattern1%,pattern2%";
  • To use all catalogs, the value should be '%': importer.catalog="%"
  • To escape a wildcard in a catalog name, use the '\' escape character. The value should be as follows: importer.catalog="test\_tables"

Exasol:

SQL 
EXA_DB

All others: empty

importer.defaultSchema
  • Only for data sources that are also supported as Analytical Storage (SQLServer, MySQL, Oracle, PostgreSQL, Redshift);
  • When the property is correctly set, SELECT INTO, CREATE, and DROP TABLE commands are enabled for that data source;
  • Must point to the original schema name in the DBMS (e.g. importer.defaultSchema=public);
  • Needs specifying where tables will be created or dropped in the source DBMS;
  • Not meant to be used with Analytical Storage data source

Please note that writing into a data source is only possible if this parameter is set.

Empty
importer.enableMetadataCache Turns on metadata cache for a single data source even when the global option is turned off. Together with importer.skipMetadataLoadOnStartup=true, it allows using materialized views after server restart when the original source is unavailable
 FALSE
importer.excludeProcedures Case-insensitive regular expression that will exclude a matching fully qualified procedure name from import
Empty
importer.excludeSchemas Comma-separated list of schemas (no % or ? wildcards allowed) to exclude listed schemas from import. A schema specified in defaultSchema or schemaPattern will be imported despite being listed in excludeSchemas. Helps to speed up metadata loading

Oracle:

SQL 
APEX_PUBLIC_USER,
DIP,
FLOWS_040100,
FLOWS_020100,
FLOWS_FILES,
MDDATA,
ORACLE_OCM,
SPATIAL_CSW_ADMIN_USR,
SPATIAL_WFS_ADMIN_USR,
XS$NULL,
BI,
HR,
OE,
PM,
IX,
SH,
SYS,
SYSTEM,
MDSYS,
CTXSYS

All others: empty

importer.excludeTables

Case-insensitive regular expression that will exclude a matching fully qualified table name from import. Does not speed up metadata loading. Here are some examples:

1. Excluding all tables in the (source) schemas sys and INFORMATION_SCHEMA:

SQL 
importer.excludeTables=(.*[.]sys[.].*|.*[.]INFORMATION_SCHEMA[.].*)

2. Excluding all tables except the ones starting with "public.br" and "public.mk" using a negative lookahead: 

SQL 
importer.excludeTables=(?!public\.(br|mk)).*

3. Excluding "tablename11" from the list ["tablename1", "tablename11", "company", "companies"]:

SQL 
importer.excludeTables=.*\.(?!\btablename1\b|\bcompan).*
  • ".*\." will match the schema portion of the table name;
  • "\b" is a word boundary. It is used to define the boundary between text characters and non-character text;
  • "\btablename1\b" will only match tablename1 and not tablename11 because of the use of "\b";
  • "\bcompan" will match "company" and "companies" because we did not use "\b" at the end to delimit a word boundary;
  • ".*" at the end is necessary to match the trailing characters after the name

Empty

importer.fetchSize

Fetch size assigned to a resultset on loading metadata

No default value

importer.importApproximateIndexes

If set to TRUE, imports approximate index information

TRUE

importer.importIndexes If set to TRUE, imports index/unique key/cardinality information FALSE
importer.importKeys If set to TRUE, imports primary and foreign keys FALSE

importer.importProcedures

If set to TRUE, imports procedures and procedure columns. Overloaded procedures can be imported with an additional option useProcedureSpecificName.

Please note that it is currently not possible to import procedures which use the same name for more than one parameter (e.g. same name for IN and OUT parameters). Such procedures can be excluded from import with the parameter excludeProcedures.
Please note that it is not always possible to import procedure result set columns due to database limitations

FALSE

TRUE only for CData connector

importer.loadColumnsTableByTableSet to TRUE to force table by table metadata processingFALSE/TRUE only for Netsuite and SAP Advantage Database Server
importer.loadMetadataWithJdbc If set to TRUE, turns off all custom metadata load ways FALSE
importer.loadSourceSystemFunctionsIf set to TRUE, data source-specific functions are loaded. Supported for Microsoft SQL Server and AzureFALSE
importer.procedureNamePattern Procedure(s) to import. If omitted, all procedures will be imported. % as a wildcard is allowed: for example, importer.procedureNamePattern=foo% will import foo , foobar, etc. W orks only in combination with importProcedures Empty

importer.quoteNameInSource

If set to FALSE, directs the Data Virtuality Server to create source queries using unquoted identifiers

TRUE

importer.renameDuplicateColumns If set to TRUE,  renames duplicate columns caused by either mixed case collisions or autoCorrectColumnNames replacing . with _. The suffix _n where n is an integer will be added to make the name unique TRUE
importer.renameDuplicateTables If set to TRUE, renames duplicate tables caused by mixed case collisions. The suffix _n where n is an integer will be added to make the name unique TRUE
importer.replaceSpecSymbsInColNamesIf set to TRUE, replaces all special symbols (any symbols not in the ^A-Za-z0-9_ sequence) to the _ symbol in column names of tables FALSE / TRUE only for BigQuery
importer.schemaPattern Schema(s) to import. If omitted or has "" value, all schemas will be imported. % as wildcard is allowed: for example, importer.schemaPattern=foo% will import foo, foobar, etc. To specify several schema names or/and patterns, values should be comma-separated and enclosed within double quotes: importer.schemaPattern="schema1,schema2,pattern1%,pattern2%". For proper escaping of special characters depending on the type of data source, check Escaping special characters in schema names or use wildcards instead: "[schema_name]" can be rewritten as "%schema%name%". Helps to speed up metadata loadingEmpty
importer.skipMetadataLoadOnStartup

If set to TRUE, allows skipping metadata loading on server startup if there's cached metadata for the data source. . Together with importer.enableMetadataCache=true, it allows using materialized views after server restart when the original source is unavailable

 FALSE
importer.tableNamePattern Table(s) to import. If omitted, all tables will be imported. % as a wildcard is allowed: for example, importer.tableNamePattern=foo% will import foo, foobar, etcEmpty
importer.tableTypes

Comma-separated list (without spaces) of table types to import. Available types depend on the DBMS. Usual format: "TABLE,VIEW".

Other typical types are "SYSTEM TABLE", "GLOBAL TEMPORARY", "LOCAL TEMPORARY", "ALIAS", "SYNONYM"

Empty
importer.useCatalogName If set to TRUE, uses any non-null/non-empty catalogue name as part of the name in source, e.g. "catalogue"."table"."column", and in the CData Virtuality Server runtime name if useFullSchemaName is TRUE. If set to FALSE, will not use the catalogue name in either the name in source or the CData Virtuality Server runtime name. Should be set to FALSE for sources that do not fully support a catalogue concept, but return a non-null catalogue name in their metadata - such as HSQL TRUE / FALSE only for Hive and EXASOL
importer.useFullSchemaName

If set to FALSE, directs the importer to drop the source catalogue/schema from the CData Virtuality Server object name so that the CData Virtuality Server fully qualified name will be in the form of <model name>.<table name>.

Please note that this may lead to objects with duplicate names when importing from multiple schemas, which results in an exception

 TRUE
importer.useProcedureSpecificName If set to TRUE, allows the import of overloaded procedures (which will normally result in a duplicate procedure error) by using the unique procedure specific name in the CData Virtuality Server. This option will only work with JDBC 4.0 compatible drivers that report specific names FALSE
importer.widenUnsignedTypes If set to TRUE, converts unsigned types to the next widest type. For example, SQL Server reports tinyint as an unsigned type. With this option enabled, tinyint would be imported as a short instead of a byte TRUE
The names of the data source properties are case-sensitive.

Escaping wildcards in importer.catalog available since v4.0.8

Default values importer.catalog='EXA_DB' and importer.useCatalogName=FALSE available since v4.4

importer.loadSourceSystemFunctions is available since v4.6

importer.importProcedures set to TRUE by default for CData connector since v4.7

Distribution and Sort Keys

Redshift does not support indexes but supports sort and distribution keys that can be used to improve the performance of queries. With respect to indexes, these keys must be defined when the table is created.

Sort Keys

SORTKEYs are created by analyzing the currently recommended indexes collected for each optimization. They can be specified both at column and table levels. It is possible to specify only one SORTKEY column (at column level) or multiple columns (at table level).

Since it is possible to specify only one SORTKEY (with one or more columns) at the table level, we decided to create a SORTKEY corresponding to the recommended index (with kind SINGLE or MULTIPLE) with the highest frequency. The system will create then a SORTKEY with one column or with multiple columns if the highest frequency index is SINGLE or MULTIPLE, respectively.

Columns that are normally recommended for index creation are used to define sort and distribution keys.

Distribution Keys

DISTKEYs are not automatically recommended by the system and need to be manually created by the user. Here are two things to keep in mind:

  • It is not possible to specify more than one DISTKEY for each recommended optimization;
  • IndexType of a DISTKEY must be set to MANUAL (which is the default, so you can skip this step).

Distribution Style

The data distribution style is defined for the whole table. Amazon Redshift distributes the rows of a table to the compute nodes according to the distribution style specified for the table. The distribution style that you select for tables affects the overall performance of your database.

StyleDescription
EVENThe data in the table is spread evenly across the nodes in a cluster in a round-robin distribution. Row IDs are used to determine the distribution, and roughly the same number of rows are distributed to each node. This is the default distribution method
KEYThe data is distributed by the values in the DISTKEY column. When you set the joining columns of joining tables as distribution keys, the joining rows from both tables are collocated on the compute nodes. When data is collocated, the optimizer can perform joins more efficiently. If you specify DISTSTYLE KEY, you must name a DISTKEY column
ALLA copy of the entire table is distributed to every node. This distribution style ensures that all the rows required for any join are available on every node, but it multiplies storage requirements and increases the load and maintenance times for the table. ALL distribution can improve execution time when used with certain dimension tables where KEY distribution is not appropriate, but performance improvements must be weighed against maintenance costs

Internal

SORTKEY and DISTKEY created for a table in Redshift can be checked with a query like this (to be executed directly on Redshift):

SQL 
SELECT tablename, "column", type, encoding, distkey, sortkey FROM pg_table_def WHERE tablename LIKE 'mat_table%';

Please note that the schema containing the table has to be in the search path.

Usage Examples

SORTKEY, DISTKEY, and DISTSTYLE are passed as OPTIONS. They are added to the CREATE TABLE or SELECT INTO command as shown below:

SQL 
CREATE TABLE source.table_name (id integer, name varchar(255))
OPTIONS (DISTKEY 'id', SORTKEY 'id,name') ;;
  
SELECT * INTO target.table_name FROM source.table_name
OPTIONS (SORTKEY 'id', DISTSTYLE 'EVEN') ;;

Redshift Spectrum

The Redshift JDBC driver exposes Spectrum tables as EXTERNAL TABLE. In order to have your Redshift data source list Spectrum tables, adjust the data source parameter importer.tableTypes accordingly by specifying e.g. importer.tableTypes="TABLE,VIEW,EXTERNAL TABLE".

See Also

Using S3 to Ingest Data into Redshift instead of using SQL INSERT statements

Show Running Queries on Redshift via Native Interface for the 200 most recent queries


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