- In general, a quoted (single or double) string refers to a literal string whereas a string without quotation marks refers to a column name.
Example:
- Column name: - total - myTable.total - myCatalog.myTable.total
- Literal: - “Madrid” - ‘California' - “New York City”
- In the near future, many statements and statement extensions will be supported.
This document describes the main features of CROSSDATA and the syntax of the supported operations. The CROSSDATA language is a SQL-like language that unifies the treatment of streaming and batch data into a single language.
The CROSSDATA language provides the following benefits over the existing SQL implementation.
- Unified language - Real time and batch support in a single platform.
- Improved INSERT INTO - Primary key and associated indexes are defined when creating the table.
- Improved SELECT queries - Selection windows - Joins
- Centralized schema
- Mutable data
- P2P storage backend (if Stratio Cassandra is used as datastore)
- Use of data types from any data source.
This section describes the features of the CROSSDATA language. The language has been defined by extending the current SQL grammar to support the required streaming features, and to provide new query capabilities. This section introduces the syntax of the supported statements highlighting the new additions.
The language supports the following set of operations based on the SQL language .
The following elements are defined as:
- Identifier: Used to identify catalogs, tables, columns and other objects. An identifier is a token matching the regular expression [a-zA-Z0-9_]*.
- Values: A value is a text representation of any of the supported data types.
The following non-terminal symbols appear in the grammar:
- <identifier> ::= LETTER (LETTER | DIGIT | '_')*
- <literal> ::= “ (~”)* ” | ‘ (~')* '
- <JSON> ::= '{' (<literal> ':' <JSON-value>)* '}'
- <JSON-value> ::= ( <literal> | <boolean> | <integer> | <decimal> )
- <catalog_name> ::= <identifier>
- <tablename> ::= (<catalog_name> '.')? <identifier>
- <columnname> ::= (<tablename> '.')? <identifier>
- <indexname> ::= <tablename> '.' <identifier>
- <property> ::= (<literal> | <identifier> ) '=' ( <literal> | <constant> )
- <data-types> = TEXT | BIGINT | INT | DOUBLE | FLOAT | BOOLEAN
- TEXT
- VARCHAR
- BIGINT
- INT
- DOUBLE
- FLOAT
- BOOLEAN
- LIST
ADD DATASTORE <path> ';'
Example:
ADD DATASTORE “/home/stratio/crossdata/cassandra.xml”;
DROP DATASTORE <datastore-name> ';'
Example:
DROP DATASTORE cassandra;
ADD CONNECTOR <path> ';'
Examples:
ADD CONNECTOR “/home/stratio/crossdata/connectors/connector_native_cassandra.xml”;
DROP CONNECTOR <connector-name> ';'
Examples:
DROP CONNECTOR cassandra_connector;
ATTACH CLUSTER (IF NOT EXISTS)? <cluster_name> ON DATASTORE <datastore_name> WITH OPTIONS <JSON> ';'
Example:
ATTACH CLUSTER production_madrid ON DATASTORE cassandra WITH OPTIONS {'Hosts': '[127.0.0.1]', 'port': 9160};
ALTER CLUSTER (IF EXISTS)? <cluster_name> WITH <JSON> ';'
Example:
ALTER CLUSTER production_madrid WITH {"port": 9161};
DETACH CLUSTER <cluster_name>';'
Example:
DETACH CLUSTER production_madrid;
ATTACH CONNECTOR <connector-name> TO <cluster-name> WITH OPTIONS <JSON>';'
Example:
ATTACH CONNECTOR con_native_cassandra TO cassandra_production WITH OPTIONS {'DefaultLimit': '1000'};
DETACH CONNECTOR <connector-name> FROM <cluster-name>';'
Example:
DETACH CONNECTOR con_native_cassandra FROM cassandra_production;
CREATE CATALOG (IF NOT EXISTS)? <catalog_name> (WITH <JSON>)? ';'
Example:
CREATE CATALOG catalog1 WITH {"comment": "This is a comment"};
ALTER CATALOG (IF NOT EXISTS)? <catalog_name> (WITH <JSON>)? ';'
Example:
ALTER CATALOG catalog1 WITH {"comment": "This is a comment"};
DROP CATALOG (IF EXISTS)? <catalog_name> ';'
Example:
DROP CATALOG catalog1;
USE <catalog_name> ';'
Example:
USE sales;
CREATE TABLE (IF NOT EXISTS)? <tablename> ON CLUSTER <clusterName> '('<column-definition> (',' <column-definition> )* ')' (WITH <JSON>)? ';'
<column-definition> ::= <identifier> <type> ( PRIMARY KEY )? | PRIMARY KEY '(' <partition-key> (',' <identifier> )* ')'
<partition-key> ::= <partition-key> | '(' <partition-key> ( ',' <identifier> )* ')'
Example:
CREATE TABLE tableTest ON CLUSTER cassandra_prod (id int PRIMARY KEY, name text);
- ALTER TABLE <tablename>
- (ALTER <column-name> <data-types> |ADD <column-name> <data-types> |DROP <column-name>)? (WITH <JSON>)?';'
Example:
ALTER TABLE tableTest ADD timestamp INT;
- UPDATE <tablename>
- (USING option (AND option)*)? SET assignment (COMMA assignment)* (WHERE <where-clause>)? (WITH <JSON>)? ';'
<assignment> ::= <column-name> = <value-assignment>
<value-assignment> ::= <value> | <column-name> <operator> <value-assignment>
<where-clause> ::= <relation> ( AND <relation> )*
<relation> ::= <identifier> ('=' | '<' | '>' | '<=' | '>=' | '<>' | 'MATCH') <data-types>
Example:
UPDATE tableTest SET value = value + 900 WHERE age > 30;
DROP TABLE (IF EXISTS)? <tablename> ';'
Example:
DROP TABLE tableTest;
TRUNCATE <tablename> ';'
Example:
TRUNCATE tableTest;
REGISTER TABLE (IF NOT EXISTS)? <tablename> ON CLUSTER <clusterName> '('<column-definition> (',' <column-definition> )* ')' (WITH <JSON>)? ';'
<column-definition> ::= <identifier> <type> ( PRIMARY KEY )? | PRIMARY KEY '(' <partition-key> (',' <identifier> )* ')'
<partition-key> ::= <partition-key> | '(' <partition-key> ( ',' <identifier> )* ')'
Example:
REGISTER TABLE tableTest ON CLUSTER cassandra_prod (id int PRIMARY KEY, name text);
UNREGISTER TABLE (IF EXISTS)? <tablename> ';'
Example:
UNREGISTER TABLE tableTest;
DELETE FROM <tablename> (WHERE <where-clause>)? ';'
<where-clause> ::= <relation> ( AND <relation> )*
<relation> ::= <identifier> ('=' | '<' | '>' | '<=' | '>=' | '<>' | 'MATCH') <data-types>
Example:
DELETE FROM tableTest WHERE income < 100;
INSERT INTO <tablename> '('<identifier> (',' <identifier> )*')' VALUES '('<data-types> (', ' <term-or-literal> )* ')' (IF NOT EXISTS)? WHEN <where-clause> (WITH <JSON>)? ';'
Example:
INSERT INTO mykeyspace.tablename (ident1, ident2) VALUES (-3.75, 'term2') IF NOT EXISTS;
CREATE (<index-type>)? INDEX (IF NOT EXISTS)? <index-name> ON <table-name> '(' <column-names> ')' (WITH <JSON>)? ';'
<index-type> ::= DEFAULT | FULL_TEXT | CUSTOM
Example:
CREATE FULL_TEXT INDEX revenueIndex ON tabletest (revenue);
DROP INDEX (IF EXISTS)? <indexname> ';'
Example:
DROP INDEX IF EXISTS tabletest.revenueIndex;
SELECT <select-list> FROM <tablename> (AS <identifier>)? (WITH WINDOW <integer> <time-unit>)? ((<inner-type>)? JOIN <tablename> (AS <identifier>) ON <field1>=<field2>)? (WHERE <where-clause>)? (ORDER BY <select-list>)? (GROUP BY <select-list>)? (LIMIT <integer>)? ';'
<selection-list> ::= <identifier> (AS <identifier>)? (',' <selector> (AS <identifier>)? )* | '*'
<where-clause> ::= <relation> ( AND <relation> )*
<relation> ::= <identifier> <comparator> <data-types>
<inner-type> ::= INNER | (RIGHT | LEFT | FULL) OUTER | FULL NATURAL | CROSS
<comparator> ::= ('=' | '<' | '>' | '<=' | '>=' | '<>' | 'MATCH' | 'LIKE' | 'IN' | 'BETWEEN')
LIKE, IN and BETWEEN comparators can be preceded by the modifier NOT.
Example:
SELECT field1, field2 FROM demo.clients AS table1 INNER JOIN sales AS table2 ON identifier = codeID;
Implicit joins are also supported when only 2 tables are involved:
SELECT <select-list> FROM <tablename> (AS <identifier>)? ',' <tablename> (AS <identifier>)? (WITH WINDOW <integer> <time-unit>)? ON <field1>=<field2> (WHERE <where-clause>)? (ORDER BY <select-list>)? (GROUP BY <select-list>)? (LIMIT <integer>)? ';'
Example:
SELECT * FROM demo.clients, demo.sales ON clients.identifier = sales.codeID;
Explain plan for a specific command according to the current state of the system.
EXPLAIN PLAN FOR <crossdata-statement> ';'
Example:
EXPLAIN PLAN FOR Select * from demoCatalog.demoCatalog;
Remove all data stored in the system (in all servers), including information related to datastores, clusters and connectors. Connectors status are the only metadata kept by the system after issuing this command.
RESET SERVERDATA ';'
Example:
RESET SERVERDATA;
Remove all metadata related to catalogs, tables, indexes and columns.
CLEAN METADATA ';'
Example:
CLEAN METADATA;
Describe all the information related to datastores, clusters and connectors.
DESCRIBE SYSTEM ';'
Example:
DESCRIBE SYSTEM;
Describe all the datastores registered in the system.
DESCRIBE DATASTORES ';'
Example:
DESCRIBE DATASTORES;
Describe information related to a specific datastore.
DESCRIBE DATASTORE <datastore-name> ';'
Example:
DESCRIBE DATASTORE cassandra;
Describe all the clusters registered in the system.
DESCRIBE CLUSTERS ';'
Example:
DESCRIBE CLUSTERS;
Describe information related to a specific cluster.
DESCRIBE CLUSTER <cluster-name> ';'
Example:
DESCRIBE CLUSTER production;
Describe all the connectors registered in the system.
DESCRIBE CONNECTORS;
Example:
DESCRIBE CONNECTORS;
Describe the specified connector.
DESCRIBE CONNECTOR <connector-name> ';'
Example:
DESCRIBE CONNECTOR cassandra_connector;
List of the catalogs created in the system.
DESCRIBE CATALOGS ';'
Example:
DESCRIBE CATALOGS;
Describe the specified catalog.
DESCRIBE CATALOG <catalog-name> ';'
Example:
DESCRIBE CATALOG catalog1;
List of the tables created in a specific catalog.
DESCRIBE TABLES (FROM <catalog-name>)? ';'
Example:
DESCRIBE TABLES FROM myCatalog;
Describe the specified table.
DESCRIBE TABLE <table-name> ';'
Example:
DESCRIBE TABLE catalog1.table;
Discover metadata from a specified cluster. This command provides information about catalogs and tables already existent on a cluster.
DISCOVER METADATA ON CLUSTER <cluster-name> ';'
Example:
DISCOVER METADATA ON CLUSTER productionCluster;
Import all the metadata from a specific cluster. This command incorporates to the Crossdata servers all the catalogs metadata and their underlying metadata.
IMPORT CATALOGS FROM CLUSTER <cluster-name> ';'
Example:
IMPORT CATALOGS FROM CLUSTER cluster_name;
Import all the metadata from a specific catalog. This command incorporates to the the Crossdata servers a catalog metadata and its underlying metadata.
IMPORT CATALOG <catalog-name> FROM CLUSTER <cluster-name> ';'
Example:
IMPORT CATALOG catalog_name FROM CLUSTER cluster_name;
Import metadata of a specific table. This command incorporates to the the Crossdata servers a table metadata and its underlying metadata.
IMPORT TABLE <table-name> FROM CLUSTER <cluster-name> ';'
Example:
IMPORT TABLE myCatalog.myTable FROM CLUSTER myCluster;
This section describes the specific and special features of the CROSSDATA shell:
Shell accepts comments: * One line comment: line starts with "//" or "#".
` > // This is a one line comment`` > /# This is also a one line comment`
- Multiline comment: starts with a line starting with "/" and ends with a line ending with "/"
*
` > /* This is a `*` > multiline `*` > comment */ `
How to exit from the shell: *
` > exit`*` > quit`Help: * A help entry is available for every command, just type "help <command>"
` > help create`
Script: * You can execute a script upon launching the shell. The script will be executed first, and the prompt will be shown afterwards. Run the shell with an input argument "--script <path-to-xdql-file>"
` > mvn exec:java -pl crossdata-shell -Dexec.mainClass="com.stratio.crossdata.sh.Shell" -Dexec.args="--script /path/script.xdql"`