Storm SQL uses Apache Calcite to parse and evaluate the SQL statements. Storm SQL also adopts Rex compiler from Calcite, so Storm SQL is expected to handle SQL dialect recognized by Calcite's default SQL parser.

The page is based on Calcite SQL reference on website, and removes the area Storm SQL doesn't support, and also adds the area Storm SQL supports.

Please read Storm SQL integration page first to see what features Storm SQL supports.

Grammar

Calcite provides broader SQL Grammar. But Storm SQL is not database system and handles streaming data, so only subset of grammar is supported. Storm SQL doesn't redefine SQL Grammar and just utilize the parser Calcite provided, so SQL statements are still parsed based on Calcite's SQL Grammar.

SQL grammar in BNF-like form.

statement:
      setStatement
  |   resetStatement
  |   explain
  |   describe
  |   insert
  |   update
  |   merge
  |   delete
  |   query

setStatement:
      [ ALTER ( SYSTEM | SESSION ) ] SET identifier '=' expression

resetStatement:
      [ ALTER ( SYSTEM | SESSION ) ] RESET identifier
  |   [ ALTER ( SYSTEM | SESSION ) ] RESET ALL

explain:
      EXPLAIN PLAN
      [ WITH TYPE | WITH IMPLEMENTATION | WITHOUT IMPLEMENTATION ]
      [ EXCLUDING ATTRIBUTES | INCLUDING [ ALL ] ATTRIBUTES ]
      FOR ( query | insert | update | merge | delete )

describe:
      DESCRIBE DATABASE databaseName
   |  DESCRIBE CATALOG [ databaseName . ] catalogName
   |  DESCRIBE SCHEMA [ [ databaseName . ] catalogName ] . schemaName
   |  DESCRIBE [ TABLE ] [ [ [ databaseName . ] catalogName . ] schemaName . ] tableName [ columnName ]
   |  DESCRIBE [ STATEMENT ] ( query | insert | update | merge | delete )

insert:
      ( INSERT | UPSERT ) INTO tablePrimary
      [ '(' column [, column ]* ')' ]
      query

update:
      UPDATE tablePrimary
      SET assign [, assign ]*
      [ WHERE booleanExpression ]

assign:
      identifier '=' expression

merge:
      MERGE INTO tablePrimary [ [ AS ] alias ]
      USING tablePrimary
      ON booleanExpression
      [ WHEN MATCHED THEN UPDATE SET assign [, assign ]* ]
      [ WHEN NOT MATCHED THEN INSERT VALUES '(' value [ , value ]* ')' ]

delete:
      DELETE FROM tablePrimary [ [ AS ] alias ]
      [ WHERE booleanExpression ]

query:
      values
  |   WITH withItem [ , withItem ]* query
  |   {
          select
      |   selectWithoutFrom
      |   query UNION [ ALL ] query
      |   query EXCEPT query
      |   query INTERSECT query
      }
      [ ORDER BY orderItem [, orderItem ]* ]
      [ LIMIT { count | ALL } ]
      [ OFFSET start { ROW | ROWS } ]
      [ FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ]

withItem:
      name
      [ '(' column [, column ]* ')' ]
      AS '(' query ')'

orderItem:
      expression [ ASC | DESC ] [ NULLS FIRST | NULLS LAST ]

select:
      SELECT [ STREAM ] [ ALL | DISTINCT ]
          { * | projectItem [, projectItem ]* }
      FROM tableExpression
      [ WHERE booleanExpression ]
      [ GROUP BY { groupItem [, groupItem ]* } ]
      [ HAVING booleanExpression ]
      [ WINDOW windowName AS windowSpec [, windowName AS windowSpec ]* ]

selectWithoutFrom:
      SELECT [ ALL | DISTINCT ]
          { * | projectItem [, projectItem ]* }

projectItem:
      expression [ [ AS ] columnAlias ]
  |   tableAlias . *

tableExpression:
      tableReference [, tableReference ]*
  |   tableExpression [ NATURAL ] [ LEFT | RIGHT | FULL ] JOIN tableExpression [ joinCondition ]

joinCondition:
      ON booleanExpression
  |   USING '(' column [, column ]* ')'

tableReference:
      tablePrimary
      [ [ AS ] alias [ '(' columnAlias [, columnAlias ]* ')' ] ]

tablePrimary:
      [ [ catalogName . ] schemaName . ] tableName
      '(' TABLE [ [ catalogName . ] schemaName . ] tableName ')'
  |   [ LATERAL ] '(' query ')'
  |   UNNEST '(' expression ')' [ WITH ORDINALITY ]
  |   [ LATERAL ] TABLE '(' [ SPECIFIC ] functionName '(' expression [, expression ]* ')' ')'

values:
      VALUES expression [, expression ]*

groupItem:
      expression
  |   '(' ')'
  |   '(' expression [, expression ]* ')'
  |   CUBE '(' expression [, expression ]* ')'
  |   ROLLUP '(' expression [, expression ]* ')'
  |   GROUPING SETS '(' groupItem [, groupItem ]* ')'

windowRef:
      windowName
  |   windowSpec

windowSpec:
      [ windowName ]
      '('
      [ ORDER BY orderItem [, orderItem ]* ]
      [ PARTITION BY expression [, expression ]* ]
      [
          RANGE numericOrIntervalExpression { PRECEDING | FOLLOWING }
      |   ROWS numericExpression { PRECEDING | FOLLOWING }
      ]
      ')'

In merge, at least one of the WHEN MATCHED and WHEN NOT MATCHED clauses must be present.

In orderItem, if expression is a positive integer n, it denotes the nth item in the SELECT clause.

An aggregate query is a query that contains a GROUP BY or a HAVING clause, or aggregate functions in the SELECT clause. In the SELECT, HAVING and ORDER BY clauses of an aggregate query, all expressions must be constant within the current group (that is, grouping constants as defined by the GROUP BY clause, or constants), or aggregate functions, or a combination of constants and aggregate functions. Aggregate and grouping functions may only appear in an aggregate query, and only in a SELECT, HAVING or ORDER BY clause.

A scalar sub-query is a sub-query used as an expression. If the sub-query returns no rows, the value is NULL; if it returns more than one row, it is an error.

IN, EXISTS and scalar sub-queries can occur in any place where an expression can occur (such as the SELECT clause, WHERE clause, ON clause of a JOIN, or as an argument to an aggregate function).

An IN, EXISTS or scalar sub-query may be correlated; that is, it may refer to tables in the FROM clause of an enclosing query.

selectWithoutFrom is equivalent to VALUES, but is not standard SQL and is only allowed in certain conformance levels.

Keywords

The following is a list of SQL keywords. This list is also from Calcite SQL reference. Reserved keywords are bold.

A, ABS, ABSOLUTE, ACTION, ADA, ADD, ADMIN, AFTER, ALL, ALLOCATE, ALLOW, ALTER, ALWAYS, AND, ANY, ARE, ARRAY, AS, ASC, ASENSITIVE, ASSERTION, ASSIGNMENT, ASYMMETRIC, AT, ATOMIC, ATTRIBUTE, ATTRIBUTES, AUTHORIZATION, AVG, BEFORE, BEGIN, BERNOULLI, BETWEEN, BIGINT, BINARY, BIT, BLOB, BOOLEAN, BOTH, BREADTH, BY, C, CALL, CALLED, CARDINALITY, CASCADE, CASCADED, CASE, CAST, CATALOG, CATALOG_NAME, CEIL, CEILING, CENTURY, CHAIN, CHAR, CHARACTER, CHARACTERISTICTS, CHARACTERS, CHARACTER_LENGTH, CHARACTER_SET_CATALOG, CHARACTER_SET_NAME, CHARACTER_SET_SCHEMA, CHAR_LENGTH, CHECK, CLASS_ORIGIN, CLOB, CLOSE, COALESCE, COBOL, COLLATE, COLLATION, COLLATION_CATALOG, COLLATION_NAME, COLLATION_SCHEMA, COLLECT, COLUMN, COLUMN_NAME, COMMAND_FUNCTION, COMMAND_FUNCTION_CODE, COMMIT, COMMITTED, CONDITION, CONDITION_NUMBER, CONNECT, CONNECTION, CONNECTION_NAME, CONSTRAINT, CONSTRAINTS, CONSTRAINT_CATALOG, CONSTRAINT_NAME, CONSTRAINT_SCHEMA, CONSTRUCTOR, CONTAINS, CONTINUE, CONVERT, CORR, CORRESPONDING, COUNT, COVAR_POP, COVAR_SAMP, CREATE, CROSS, CUBE, CUME_DIST, CURRENT, CURRENT_CATALOG, CURRENT_DATE, CURRENT_DEFAULT_TRANSFORM_GROUP, CURRENT_PATH, CURRENT_ROLE, CURRENT_SCHEMA, CURRENT_TIME, CURRENT_TIMESTAMP, CURRENT_TRANSFORM_GROUP_FOR_TYPE, CURRENT_USER, CURSOR, CURSOR_NAME, CYCLE, DATA, DATABASE, DATE, DATETIME_INTERVAL_CODE, DATETIME_INTERVAL_PRECISION, DAY, DEALLOCATE, DEC, DECADE, DECIMAL, DECLARE, DEFAULT, DEFAULTS, DEFERRABLE, DEFERRED, DEFINED, DEFINER, DEGREE, DELETE, DENSE_RANK, DEPTH, DEREF, DERIVED, DESC, DESCRIBE, DESCRIPTION, DESCRIPTOR, DETERMINISTIC, DIAGNOSTICS, DISALLOW, DISCONNECT, DISPATCH, DISTINCT, DOMAIN, DOUBLE, DOW, DOY, DROP, DYNAMIC, DYNAMIC_FUNCTION, DYNAMIC_FUNCTION_CODE, EACH, ELEMENT, ELSE, END, END-EXEC, EPOCH, EQUALS, ESCAPE, EVERY, EXCEPT, EXCEPTION, EXCLUDE, EXCLUDING, EXEC, EXECUTE, EXISTS, EXP, EXPLAIN, EXTEND, EXTERNAL, EXTRACT, FALSE, FETCH, FILTER, FINAL, FIRST, FIRST_VALUE, FLOAT, FLOOR, FOLLOWING, FOR, FOREIGN, FORTRAN, FOUND, FRAC_SECOND, FREE, FROM, FULL, FUNCTION, FUSION, G, GENERAL, GENERATED, GET, GLOBAL, GO, GOTO, GRANT, GRANTED, GROUP, GROUPING, HAVING, HIERARCHY, HOLD, HOUR, IDENTITY, IMMEDIATE, IMPLEMENTATION, IMPORT, IN, INCLUDING, INCREMENT, INDICATOR, INITIALLY, INNER, INOUT, INPUT, INSENSITIVE, INSERT, INSTANCE, INSTANTIABLE, INT, INTEGER, INTERSECT, INTERSECTION, INTERVAL, INTO, INVOKER, IS, ISOLATION, JAVA, JOIN, K, KEY, KEY_MEMBER, KEY_TYPE, LABEL, LANGUAGE, LARGE, LAST, LAST_VALUE, LATERAL, LEADING, LEFT, LENGTH, LEVEL, LIBRARY, LIKE, LIMIT, LN, LOCAL, LOCALTIME, LOCALTIMESTAMP, LOCATOR, LOWER, M, MAP, MATCH, MATCHED, MAX, MAXVALUE, MEMBER, MERGE, MESSAGE_LENGTH, MESSAGE_OCTET_LENGTH, MESSAGE_TEXT, METHOD, MICROSECOND, MILLENNIUM, MIN, MINUTE, MINVALUE, MOD, MODIFIES, MODULE, MONTH, MORE, MULTISET, MUMPS, NAME, NAMES, NATIONAL, NATURAL, NCHAR, NCLOB, NESTING, NEW, NEXT, NO, NONE, NORMALIZE, NORMALIZED, NOT, NULL, NULLABLE, NULLIF, NULLS, NUMBER, NUMERIC, OBJECT, OCTETS, OCTET_LENGTH, OF, OFFSET, OLD, ON, ONLY, OPEN, OPTION, OPTIONS, OR, ORDER, ORDERING, ORDINALITY, OTHERS, OUT, OUTER, OUTPUT, OVER, OVERLAPS, OVERLAY, OVERRIDING, PAD, PARAMETER, PARAMETER_MODE, PARAMETER_NAME, PARAMETER_ORDINAL_POSITION, PARAMETER_SPECIFIC_CATALOG, PARAMETER_SPECIFIC_NAME, PARAMETER_SPECIFIC_SCHEMA, PARTIAL, PARTITION, PASCAL, PASSTHROUGH, PATH, PERCENTILE_CONT, PERCENTILE_DISC, PERCENT_RANK, PLACING, PLAN, PLI, POSITION, POWER, PRECEDING, PRECISION, PREPARE, PRESERVE, PRIMARY, PRIOR, PRIVILEGES, PROCEDURE, PUBLIC, QUARTER, RANGE, RANK, READ, READS, REAL, RECURSIVE, REF, REFERENCES, REFERENCING, REGR_AVGX, REGR_AVGY, REGR_COUNT, REGR_INTERCEPT, REGR_R2, REGR_SLOPE, REGR_SXX, REGR_SXY, REGR_SYY, RELATIVE, RELEASE, REPEATABLE, RESET, RESTART, RESTRICT, RESULT, RETURN, RETURNED_CARDINALITY, RETURNED_LENGTH, RETURNED_OCTET_LENGTH, RETURNED_SQLSTATE, RETURNS, REVOKE, RIGHT, ROLE, ROLLBACK, ROLLUP, ROUTINE, ROUTINE_CATALOG, ROUTINE_NAME, ROUTINE_SCHEMA, ROW, ROWS, ROW_COUNT, ROW_NUMBER, SAVEPOINT, SCALE, SCHEMA, SCHEMA_NAME, SCOPE, SCOPE_CATALOGS, SCOPE_NAME, SCOPE_SCHEMA, SCROLL, SEARCH, SECOND, SECTION, SECURITY, SELECT, SELF, SENSITIVE, SEQUENCE, SERIALIZABLE, SERVER, SERVER_NAME, SESSION, SESSION_USER, SET, SETS, SIMILAR, SIMPLE, SIZE, SMALLINT, SOME, SOURCE, SPACE, SPECIFIC, SPECIFICTYPE, SPECIFIC_NAME, SQL, SQLEXCEPTION, SQLSTATE, SQLWARNING, SQL_TSI_DAY, SQL_TSI_FRAC_SECOND, SQL_TSI_HOUR, SQL_TSI_MICROSECOND, SQL_TSI_MINUTE, SQL_TSI_MONTH, SQL_TSI_QUARTER, SQL_TSI_SECOND, SQL_TSI_WEEK, SQL_TSI_YEAR, SQRT, START, STATE, STATEMENT, STATIC, STDDEV_POP, STDDEV_SAMP, STREAM, STRUCTURE, STYLE, SUBCLASS_ORIGIN, SUBMULTISET, SUBSTITUTE, SUBSTRING, SUM, SYMMETRIC, SYSTEM, SYSTEM_USER, TABLE, TABLESAMPLE, TABLE_NAME, TEMPORARY, THEN, TIES, TIME, TIMESTAMP, TIMESTAMPADD, TIMESTAMPDIFF, TIMEZONE_HOUR, TIMEZONE_MINUTE, TINYINT, TO, TOP_LEVEL_COUNT, TRAILING, TRANSACTION, TRANSACTIONS_ACTIVE, TRANSACTIONS_COMMITTED, TRANSACTIONS_ROLLED_BACK, TRANSFORM, TRANSFORMS, TRANSLATE, TRANSLATION, TREAT, TRIGGER, TRIGGER_CATALOG, TRIGGER_NAME, TRIGGER_SCHEMA, TRIM, TRUE, TYPE, UESCAPE, UNBOUNDED, UNCOMMITTED, UNDER, UNION, UNIQUE, UNKNOWN, UNNAMED, UNNEST, UPDATE, UPPER, UPSERT, USAGE, USER, USER_DEFINED_TYPE_CATALOG, USER_DEFINED_TYPE_CODE, USER_DEFINED_TYPE_NAME, USER_DEFINED_TYPE_SCHEMA, USING, VALUE, VALUES, VARBINARY, VARCHAR, VARYING, VAR_POP, VAR_SAMP, VERSION, VIEW, WEEK, WHEN, WHENEVER, WHERE, WIDTH_BUCKET, WINDOW, WITH, WITHIN, WITHOUT, WORK, WRAPPER, WRITE, XML, YEAR, ZONE.

Identifiers

Identifiers are the names of tables, columns and other metadata elements used in a SQL query.

Unquoted identifiers, such as emp, must start with a letter and can only contain letters, digits, and underscores. They are implicitly converted to upper case.

Quoted identifiers, such as "Employee Name", start and end with double quotes. They may contain virtually any character, including spaces and other punctuation. If you wish to include a double quote in an identifier, use another double quote to escape it, like this: "An employee called ""Fred"".".

In Calcite, matching identifiers to the name of the referenced object is case-sensitive. But remember that unquoted identifiers are implicitly converted to upper case before matching, and if the object it refers to was created using an unquoted identifier for its name, then its name will have been converted to upper case also.

Data types

Scalar types

Where:

timeUnit:
  MILLENNIUM | CENTURY | DECADE | YEAR | QUARTER | MONTH | WEEK | DOY | DOW | DAY | HOUR | MINUTE | SECOND | EPOCH

Note:

• DATE, TIME and TIMESTAMP have no time zone. There is not even an implicit time zone, such as UTC (as in Java) or the local time zone. It is left to the user or application to supply a time zone.

Non-scalar types

Operators and functions

Operator precedence

The operator precedence and associativity, highest to lowest.

Comparison operators

Not supported yet on Storm SQL:

Storm SQL doesn't support sub-query yet, so above operators don't work properly. This will be addressed in near future.

Logical operators

Arithmetic operators and functions

Character string operators and functions

Not implemented:

• SUBSTRING(string FROM regexp FOR regexp)

Binary string operators and functions

Known bugs:

Calcite 1.9.0 has bugs on binary SUBSTRING functions which throws exception while compiling SQL statements. This can be fixed to higher version of Calcite.

Date/time functions

Not implemented:

• EXTRACT(timeUnit FROM interval)
• CEIL(interval)
• FLOOR(interval)
• datetime - datetime timeUnit [ TO timeUnit ]
• interval OVERLAPS interval
• + interval
• - interval
• interval + interval
• interval - interval
• interval / interval
• datetime + interval
• datetime - interval

Note on Storm SQL:

SQL standard states that above operators should return the same value while evaluating query. Storm SQL converts each query to Trident topology and run, so technically current date / time should be fixed while evaluating SQL statement. Because of this limitation, current date / time will be fixed while creating Trident topology, and these operators should return the same value in the lifecycle of topology.

System functions

Not supported yet on Storm SQL:

These operators are not making sense of Storm SQL's runtime, so it may be never supported unless we find out proper semantics.

Conditional functions and operators

Type conversion

Value constructors

Collection functions

See also: UNNEST relational operator converts a collection to a relation.

JDBC function escape

Numeric

Not implemented:

• {fn ACOS(numeric)} - Returns the arc cosine of numeric
• {fn ASIN(numeric)} - Returns the arc sine of numeric
• {fn ATAN(numeric)} - Returns the arc tangent of numeric
• {fn ATAN2(numeric, numeric)}
• {fn CEILING(numeric)} - Rounds numeric up, and returns the smallest number that is greater than or equal to numeric
• {fn COS(numeric)} - Returns the cosine of numeric
• {fn COT(numeric)}
• {fn DEGREES(numeric)} - Converts numeric from radians to degrees
• {fn FLOOR(numeric)} - Rounds numeric down, and returns the largest number that is less than or equal to numeric
• {fn PI()} - Returns a value that is closer than any other value to pi
• {fn RADIANS(numeric)} - Converts numeric from degrees to radians
• {fn RAND(numeric)}
• {fn ROUND(numeric, numeric)}
• {fn SIGN(numeric)}
• {fn SIN(numeric)} - Returns the sine of numeric
• {fn SQRT(numeric)} - Returns the square root of numeric
• {fn TAN(numeric)} - Returns the tangent of numeric
• {fn TRUNCATE(numeric, numeric)}

String

Known bugs:

Calcite 1.9.0 throws exception on {fn LOCATE} with position parameter, {fn LTRIM} and {fn RTRIM} while compiling SQL statement. This can be fixed to higher version of Calcite.

Not implemented:

• {fn ASCII(string)} - Convert a single-character string to the corresponding ASCII code, an integer between 0 and 255
• {fn CHAR(string)}
• {fn DIFFERENCE(string, string)}
• {fn LEFT(string, integer)}
• {fn REPEAT(string, integer)}
• {fn REPLACE(string, string, string)}
• {fn RIGHT(string, integer)}
• {fn SOUNDEX(string)}
• {fn SPACE(integer)}

Date/time

Not implemented:

• {fn DAYNAME(date)}
• {fn DAYOFMONTH(date)}
• {fn DAYOFWEEK(date)}
• {fn DAYOFYEAR(date)}
• {fn HOUR(time)}
• {fn MINUTE(time)}
• {fn MONTH(date)}
• {fn MONTHNAME(date)}
• {fn SECOND(time)}
• {fn WEEK(date)}
• {fn YEAR(date)}

System

Not implemented:

• {fn DATABASE()}
• {fn IFNULL(value, value)}
• {fn USER(value, value)}
• {fn CONVERT(value, type)}

Aggregate functions

Storm SQL doesn't support aggregation yet.

Window functions

Storm SQL doesn't support windowing yet.

Grouping functions

Storm SQL doesn't support grouping functions.

User-defined functions

Users can define user defined function (scalar) using CREATE FUNCTION statement. For example, the following statement defines MYPLUS function which uses org.apache.storm.sql.TestUtils$MyPlus class.

CREATE FUNCTION MYPLUS AS 'org.apache.storm.sql.TestUtils$MyPlus'

Storm SQL determines whether the function as scalar or aggregate by checking which methods are defined. If the class defines evaluate method, Storm SQL treats the function as scalar.

Example of class for scalar function is here:

  public class MyPlus {
    public static Integer evaluate(Integer x, Integer y) {
      return x + y;
    }
  }

Please note that users should use --jars or --artifacts while running Storm SQL runner to make sure UDFs are available in classpath.

External Data Sources

Specifying External Data Sources

In StormSQL data is represented by external tables. Users can specify data sources using the CREATE EXTERNAL TABLE statement. The syntax of CREATE EXTERNAL TABLE closely follows the one defined in Hive Data Definition Language:

CREATE EXTERNAL TABLE table_name field_list
    [ STORED AS
      INPUTFORMAT input_format_classname
      OUTPUTFORMAT output_format_classname
    ]
    LOCATION location
    [ TBLPROPERTIES tbl_properties ]
    [ AS select_stmt ]

Default input format and output format are JSON. We will introduce supported formats from further section.

For example, the following statement specifies a Kafka spout and sink:

CREATE EXTERNAL TABLE FOO (ID INT PRIMARY KEY) LOCATION 'kafka://localhost:2181/brokers?topic=test' TBLPROPERTIES '{"producer":{"bootstrap.servers":"localhost:9092","acks":"1","key.serializer":"org.apache.org.apache.storm.kafka.IntSerializer","value.serializer":"org.apache.org.apache.storm.kafka.ByteBufferSerializer"}}'

Please note that users should use --jars or --artifacts while running Storm SQL runner to make sure UDFs are available in classpath.

Plugging in External Data Sources

Users plug in external data sources through implementing the ISqlTridentDataSource interface and registers them using the mechanisms of Java's service loader. The external data source will be chosen based on the scheme of the URI of the tables. Please refer to the implementation of storm-sql-kafka for more details.

Supported Formats

Avro

Avro requires users to describe the schema of record (both input and output). Schema should be described on TBLPROPERTIES. Input format needs to be described to input.avro.schema, and output format needs to be described to output.avro.schema. Schema string should be an escaped JSON so that TBLPROPERTIES is valid JSON.

Example Schema description:

"input.avro.schema": "{\"type\": \"record\", \"name\": \"large_orders\", \"fields\" : [ {\"name\": \"ID\", \"type\": \"int\"}, {\"name\": \"TOTAL\", \"type\": \"int\"} ]}"

"output.avro.schema": "{\"type\": \"record\", \"name\": \"large_orders\", \"fields\" : [ {\"name\": \"ID\", \"type\": \"int\"}, {\"name\": \"TOTAL\", \"type\": \"int\"} ]}"

CSV

It uses Standard RFC4180 CSV Parser and doesn't need any other properties.

TSV

By default TSV uses \t as delimiter, but users can set another delimiter by setting input.tsv.delimiter and/or output.tsv.delimiter. Please note that it supports only one letter for delimiter.

Supported Data Sources

Socket

Socket data source is a built-in feature so users don't need to add any artifacts to --artifacts options.

Please note that Socket data source is only for testing: it doesn't guarantee exactly-once and at-least-once.

TIP: netcat is a convenient tool for Socket: users can use netcat to connect Socket data source for either or both input and output purposes.

Kafka

Kafka data source requires below properties only when its used for output data source:

• producer: Specify Kafka Producer configuration - Please refer Kafka producer configs for details.
  • bootstrap.servers must be described in producer

Please note that storm-sql-kafka requires users to provide storm-kafka, and storm-kafka requires users to provide kafka and kafka-clients. You can use below as working reference for --artifacts option, and change dependencies version, and see it works:

org.apache.storm:storm-sql-kafka:2.0.0-SNAPSHOT,org.apache.storm:storm-kafka:2.0.0-SNAPSHOT,org.apache.kafka:kafka_2.10:0.8.2.2^org.slf4j:slf4j-log4j12,org.apache.kafka:kafka-clients:0.8.2.2

Redis

Redis data source requires below properties to be set:

• data.type: data type to be used for storing - only "STRING" and "HASH" are supported
• data.additional.key: key if data type needs both key and field (field will be used as field)
• redis.timeout: timeout in milliseconds (ex. "3000")
• use.redis.cluster: "true" if data source is Redis Cluster env., "false" otherwise.

Please note that storm-sql-redis requires users to provide storm-redis. You can use below as working reference for --artifacts option, and change dependencies version if really needed:

org.apache.storm:storm-sql-redis:2.0.0-SNAPSHOT,org.apache.storm:storm-redis:2.0.0-SNAPSHOT

MongoDB

MongoDB data source requires below properties to be set:

{"collection.name": "storm_sql_mongo", "trident.ser.field": "serfield"}

• trident.ser.field: field to store - record will be serialized and stored as BSON in this field
• collection.name: Collection name

Please note that storm-sql-mongodb requires users to provide storm-mongodb. You can use below as working reference for --artifacts option, and change dependencies version if really needed:

org.apache.storm:storm-sql-mongodb:2.0.0-SNAPSHOT,org.apache.storm:storm-mongodb:2.0.0-SNAPSHOT

Storing record with preserving fields are not supported for now.

HDFS

HDFS data source requires below properties to be set:

• hdfs.file.path: HDFS file path
• hdfs.file.name: HDFS file name - please refer to SimpleFileNameFormat
• hdfs.rotation.size.kb: HDFS FileSizeRotationPolicy in KB
• hdfs.rotation.time.seconds: HDFS TimedRotationPolicy in seconds

Please note that hdfs.rotation.size.kb and hdfs.rotation.time.seconds only one can be used for hdfs rotation.

And note that storm-sql-hdfs requires users to provide storm-hdfs. You can use below as working reference for --artifacts option, and change dependencies version if really needed:

org.apache.storm:storm-sql-hdfs:2.0.0-SNAPSHOT,org.apache.storm:storm-hdfs:2.0.0-SNAPSHOT

Also, hdfs configuration files should be provided. You can put the core-site.xml and hdfs-site.xml into the conf directory which is in Storm installation directory.