A GSQL query is a compiled data retrieval-and-computation task. Users can write queries to explore a data graph however they like, to read and make computations on the graph data along the way, to update the graph, and to deliver resulting data. A query is analogous to a user-defined procedure or function: it can have one or more input parameters, and it can produce output in two ways: by returning a value or by printing. Using a query is a three-step procedure:
CREATE QUERY: define the functionality of the query
INSTALL QUERY: compile the query
RUN QUERY: execute the query with input values
Query Action Privileges
Users with querywriter role or greater (architect, admin, and superuser) can create, install and drop queries.
Any user with queryreader role or greater for a given graph can run the queries for that graph.
To implement fine-grained control over which queries can be executed by which sets of users:
Group your queries into your desired privilege groups.
Define a graph for each privilege group. These graphs can all have the same domain if you wish.
Create your queries, assigning each to its appropriate privilege group.
CREATE QUERY defines the functionality of a query on a given graph schema.
A query has a name, a parameter list, the name of the graph being queried, an optional RETURNS type (see Section "RETURN Statement" for more details), an optional specifier for the output api, and a body. The body consists of an optional sequence of typedefs , followed by an optional sequence of declarations, then followed by one or more statements. The body defines the behavior of the query.
The DISTRIBUTED option applies only to installations where the graph has been distributed across a cluster . If specified, the query will run with a different execution model which may give better performance for queries which traverse a large portion of the cluster. Not all GSQL query language features are supported in DISTRIBUTED mode. For details, see the separate document: Distributed Query Mode.
OR REPLACE is deprecated
If the optional keywords OR REPLACE are included, then this query definition, if error-free, will replace a previous definition with the same query name. However, if there are any errors in this query definition, then the previous query definition will be maintained. If the OR REPLACE option is not used, then GSQL will reject a CREATE QUERY command that uses an existing name.
Typedefs allow the programmer to define custom types for use within the body. The declarations support definition of accumulators (see Chapter "Accumulators" for more details) and global/local variables. All accumulators and global variables must be declared before any statements. There are various types of statements that can be used within the body. Typically, the core statement(s) in the body of a query is one or more SELECT, UPDATE, INSERT, DELETE statements. The language supports conditional statements such as an IF statement as well as looping constructs such as WHILE and FOREACH. It also supports calling functions, assigning variables, printing, and modifying the graph data.
The query body may include calls to other queries. That is, the other queries are treated as subquery functions. See the subsection on "Queries as Functions".
This table lists the supported data types for input parameters and return values.
A statement is a standalone instruction that expresses an action to be carried out. The most common statements are data manipulation language ( DML) statements . DML statements include the SELECT, UPDATE, INSERT INTO, DELETE FROM, and DELETE statements.
A GSQL query has two levels of statements. The upper-level statement type is called query-body-level statement , or query-body statement for short. This statement type is part of either the top-level block or a query-body control flow block. For example, each of the statements at the top level directly under CREATE QUERY is a query-body statement. If one of the statements is a CASE statement with several THEN blocks, each of the statements in the THEN blocks is also a query-body statement. Each query-body statement ends with a semicolon.
The lower-level statement type is called DML-sub-level statement or DML-sub-statement for short. This statement type is used inside certain query-body DML statements, to define particular data manipulation actions. DML-sub-statements are comma-separated. There is no comma or semicolon after the last DML-sub-statement in a block. For example, one of the top-level statements is a SELECT statement, each of the statements in its ACCUM clause is a DML-sub-statement. If one of those DML-sub-statements is a CASE statement, each of the statement in the THEN blocks is a DML-sub-statement.
There is some overlap in the types. For example, an assignStmt can be used either at the query-body level or the DML-sub-level.
Guidelines for understanding statement type hierarchy:
Top-level statements are Query-Body type (each statement ending with a semicolon).
The statements within a DML statement are DML-sub statements (comma-separated list).
The blocks within a Control Flow statement have the same type as the entire Control Flow statement itself.
Here is a descriptive list of query-body statements:
Here is a descriptive list of DML-sub-statements:
A query must be installed before it can be executed. The INSTALL QUERY command will install the queries listed:
INSTALL QUERY queryName1, queryName2, ...
It can also install all uninstalled queries, using either of the following commands: INSTALL QUERY * INSTALL QUERY ALL
Note: Installing takes several seconds for each query. The current version does not support concurrent installation and running of queries. Other concurrent graph operations will be delayed until the installation finishes.
The following options are available:
Reinstall the query even if the system indicates the query is already installed. This is useful for overwriting an installation that is corrupted or otherwise outdated, without having to drop and then recreate the query. If this option is not used, the GSQL shell will refuse to re-install a query that is already installed.
During standard installation, the user-defined queries are dynamically linked to the GSQL language code. Anytime after INSTALL QUERY has been performed, another statement, INSTALL QUERY -OPTIMIZE can be executed. The names of the individual queries are not needed. This operation optimizes all previously installed queries, reducing their run times by about 20%. Optimize a query if query run time is more important to you than query installation time.
Legal:
Illegal:
If you have a distributed database deployment, installing the query in DISTRIBUTED mode can increase performance for single queries - using a single worker from each available machine to yield results. Certain cases may benefit more from this option than others -- more detailed information is available on the next page: Distributed Query Mode .
Installing a query creates a REST++ endpoint. Once a query is installed, there are two ways of executing a query. One way is through the GSQL shell: RUN QUERY query_name( parameterValues ) .
Query output size limitation
There is a maximum size limit of 2GB for the result set of a SELECT block. A SELECT block is the main component of a query which searches for and returns data from the graph. If the result of the SELECT block is larger than 2GB, the system will return no data. NO error message is produced.
The query response time can be reduced by directly submitting an HTTP request to the REST++ server: send a GET request to " http://server_ip:9000/query/graphname/queryname
". If the REST++ server is local, then server_ip is localhost
. The query parameter values are either included directly in the query string of the HTTP request's URL or supplied using a data payload.
Starting with TigerGraph v1.2, the graph name is now part of the GET /query URL.
The current version does not support concurrent installation and running of queries. Other concurrent graph operations will be delayed until the installation finishes.
The following two curl commands are each equivalent to the RUN QUERY command above. The first gives the parameter values in the query string in a URL. This example illustrates the simple format for primitive data types such as INT, DOUBLE, and STRING. The second gives the parameter values through the curl command's data payload -d option.
where RunQueryExPara.dat has the exact string as the query string in the first URL.
To see a list of the parameter names and types for the user-installed GSQL queries, run the following REST++ request:
curl -X GET "http://localhost:9000/endpoints?dynamic=true"
By using the data payload option, the user can avoid using a long and complex URL. In fact, to call the same query but with different parameters, only the data payload file contents need to be changed; the HTTP request can be the same. The file loader loads the entire file, appends multiple lines into one, and uses the resulting string as the URL query string. If both a query string and a data payload are given (which we strongly discourage), both are included, where the URL query string's parameter values overwrite the values given in the data payload.
This subsection describes how to format the complex type parameter values when executing a query by RUN QUERY or curl command. More details about all parameter types are described in Section "Query Parameter Types"
When square brackets are used in a curl URL, the -g option or escape characters must be adopted. If the parameters are given by data payload (either by file or data payload string), the -g option is not needed and escape characters should not be used.
Below are examples.
This data payload option can accept a file up to 128MB by default. To increase this limit to xxx MB, use the following command:
The upper limit of this setting is 1024 MB. Raising the size limit for the data payload buffer reduces the memory available for other operations, so be cautious about increasing this limit.
For more detailed information about REST++ endpoints and requests, see the RESTPP API User Guide .
The following options are available when running a query:
Some queries run with all or almost all vertices in a SELECT statement s, e.g. PageRank algorithm. In this case, the graph processing engine can run much more efficiently in all-vertex mode. In the all-vertex mode, all vertices are always selected, and the following actions become ineffective:
Filtering with selected vertices or vertex types. The source vertex set must be all vertices.
Filtering with the WHERE clause.
Filtering with the HAVING clause.
Assigning designated vertex or designated type of vertexes. E.g. X = { vertex_type .*}
To run the query in all-vertex mode, use the -av option in shell mode or include __GQUERY__USING_ALL_ACTIVE_MODE=true
in the query string of an HTTP request.
The diagnose option can be turned on in order to produce a diagnostic monitoring log, which contains the processing time of each SELECT block . To turn on the monitoring log, use the -d option in shell mode or __GQUERY__monitor=true
in the query string of an HTTP request.
The path of the generated log file will be shown as a part of output message. An example log is shown below:
The standard output of GSQL queries is in industry-standard JSON format. A JSON object is an unordered set of key:value pairs , enclosed in curly braces. Among the acceptable data types for a JSONvalue are array and object . A JSON array is an ordered list of values , enclosed in square brackets. Since values can be objects or arrays, JSON supports hierarchical, nested structures. Strings are enclosed in double quotation marks. We also use the term field to refer to a key (or a key:value pair) of a given object.
At the top level of the JSON structure are three required fields: "error", "message", and "results". If a query is successful, the value of "error" will be "false", the "message" value will be empty, and the "results" value will be the intended output of the query. If an error or exception occurred during query execution, the "error" value will be "true", the "message" value will be a string message describing the error condition, and the "results" field will be empty.
Beginning with version 2 (v2) of the output specification, an additional top-level field is required: "version". The "version" value is an object with the following fields:
Other top-level objects, such as "code" may appear in certain circumstances. Note that the top-level objects are enclosed in curly braces, meaning that they form an unordered set. They may appear in any order.
Below is an example of the output of a successful query:
The value of the "results" key-value pair is a sequential list of the data objects specified by the PRINT statements of the query. The list order follows the order of PRINT execution. The detailed format of the PRINT statement results is described in the Chapter "Output Statements".
For backward compatibility, TigerGraph platforms whose principal output API is v2 can also produce output with API v1.
The following GSQL statement can be used to set the JSON output API configuration.
Currently, the legal values for <version_string> are "v1" and "v2". This statement sets a persistent system parameter. Each version of the TigerGraph platform is pre-configured to what was the latest output API that at the time of release. For example, platform version 1.1 is configured so that each query will produce v2 output by default.
To show the GSQL text of a query, run "SHOW QUERY query_name ". Additionally, the "ls" GSQL command lists all created queries and identifies which queries have been installed.
As of v2.3, the query_name argument can now use * or ? wildcards from Linux globbing, or it can be a regular expression, when preceded by -r. See SHOW: View Parts of the Catalog
To drop a query, run "DROP QUERY query_name ". The query will be uninstalled (if it has been installed) and removed from the dictionary. The GSQL language will refuse to drop an installed query Q if another query R is installed which calls query Q . That is, all calling queries must be dropped before or at the same time that their called subqueries are dropped.
To drop all queries,, either of the following commands can be used: DROP QUERY ALL DROP QUERY *
The scope of ALL depends on the user's current scope. If the user has set a working graph, then DROP ALL removes all the jobs for that graph. If a superuser has set their scope to be global, then DROP ALL removes all jobs across all graph spaces.
Parameter Types
any baseType (except EDGE, JSONOBJECT, JSONARRAY): INT, UINT, FLOAT, DOUBLE, STRING, BOOL, STRING, VERTEX
SET<baseType>, BAG<baseType>
Exception: EDGE type is not supported, either as a primitive parameter or as part of a complex type.
Return Types
any baseType (including EDGE): INT, UINT, FLOAT, DOUBLE, STRING, BOOL, STRING, VERTEX, EDGE, JSONOBJECT, JSONARRAY
any accumulator type, except GroupByAccum
EBNF term
Common Name
Description
assignStmt
Assignment Statement
See Chapter 6: "Declaration and Assignment Statements"
vSetVarDeclStmt
Vertex Set Variable Declaration Statement
See Chapter 6: "Declaration and Assignment Statements"
gAccumAssignStmt
Global Accumulator Assignment Statement
See Chapter 6: "Declaration and Assignment Statements"
gAccumAccumStmt
Global Accumulator Accumulation Statement
See Chapter 6: "Declaration and Assignment Statements"
funcCallStmt
Functional Call or Query Call Statement
See Chapter 6: "Declaration and Assignment Statements"
selectStmt
SELECT Statement
See Chapter 7: "SELECT Statement"
queryBodyCaseStmt
query-body CASE statement
See Chapter 8: "Control Flow Statements"
queryBodyIfStmt
query-body IF statement
See Chapter 8: "Control Flow Statements"
queryBodyWhileStmt
query-body WHILE statement
See Chapter 8: "Control Flow Statements"
queryBodyForEachStmt
query-body FOREACH statement
See Chapter 8: "Control Flow Statements"
updateStmt
UPDATE Statement
See Chapter 9: "Data Modification Statements"
insertStmt
INSERT INTO statement
See Chapter 9: "Data Modification Statements"
queryBodyDeleteStmt
Query-body DELETE Statement
See Chapter 9: "Data Modification Statements"
printStmt
PRINT Statement
See Chapter 10: "Output Statements"
logStmt
LOG Statement
See Chapter 10: "Output Statements"
returnStmt
RETURN Statement
See Chapter 10: "Output Statements"
raiseStmt
PRINT Statement
See Chapter 11: "Exception Statements"
tryStmt
TRY Statement
See Chapter 11: "Exception Statements"
EBNF term
Common Name
Description
assignStmt
Assignment Statement
See Chapter 6: "Declaration and Assignment Statements"
funcCallStmt
Functional Call Statement
See Chapter 6: "Declaration and Assignment Statements"
gAccumAccumStmt
Global Accumulator Accumulation Statement
See Chapter 6: "Declaration and Assignment Statements"
vAccumFuncCall
Vertex-attached Accumulator Function Call Statement
See Chapter 6: "Declaration and Assignment Statements"
localVarDeclStmt
Local Variable Declaration Statement
See Chapter 7: "SELECT Statement"
insertStmt
INSERT INTO Statement
See Chapter 8: "Control Flow Statements"
DMLSubDeleteStmt
DML-sub DELETE Statement
See Chapter 9: "Data Modification Statements"
DMLSubcaseStmt
DML-sub CASE statement
See Chapter 9: "Data Modification Statements"
DMLSubIfStmt
DML-sub IF statement
See Chapter 9: "Data Modification Statements"
DMLSubForEachStmt
DML-sub FOREACH statement
See Chapter 9: "Data Modification Statements"
DMLSubWhileStmt
DML-sub WHILE statement
See Chapter 9: "Data Modification Statements"
logStmt
LOG Statement
See Chapter 10: "Output Statements"
Parameter type
RUN QUERY
Query string for GET /query HTTP Request
SET or BAG of primitives
Square brackets enclose the collection of values.
Example: a set p1 of integers: [1,5,10]
Assign multiple values to the same parameter name.
Example: a set p1 of integers: p1=1&p1=5&p1=10
VERTEX<type>
If the vertex type is specified in the query definition, then the vertex argument is simply vertex_id
Example: vertex type is person and desired id is person2. "person2"
parameterName=vertex_id
Example: vertex type is person and desired id is person2. vp=person2
VERTEX
(type not pre-specified)
If the type is not defined in the query definition, then the argument must provide both the id and type in parentheses:(vertex_id, vertex_type)
Example: a vertex va w ith id="person1" and type="person: ("person1","person")
parameterName=vertex_id¶meterName.type=vertex_type
Example: parameter vertex va when type="person" and id="person1": va=person1&va.type=person
SET or BAG of VERTEX<type>
Same as a SET or BAG of primitives, where the primitive type is vertex_id. Example: [ "person3", "person4" ]
Same as a SET or BAG of primitives, where the primitive type is vertex_id. Example: vp=person3&vp=person4
SET or BAG of VERTEX
(type not pre-specified)
Same as a SET or BAG of vertices, with vertex type not pre-specified. Square brackets enclose a comma-separated list of vertex (id, type) pairs. Mixed types are permitted. Example: [ ("person1","person") , ("11","post") ]
The SET or BAG must be treated like an array, specifying the first, second, etc. elements with indices [0], [1], etc. The example below provides the same input arguments as the RUN QUERY example to the left.
vp[0]=person1&vp[0].type=person&vp[1]=11&vp[1].type=post
"version" field
value
api
A string specifying the output API version. Values are specified as follows:
"v1": Output API used in TigerGraph platform v0.8 through v1.0. If the output does not have a "version" field, the JSON format is presumed to be v1.
"v2": Output API introduced in TigerGraph platform v1.1. This is the latest API. (Note: for backward compatibility, TigerGraph platforms which support the v2 output api can be configured to produce either v1 or v2 output.)
schema
An integer representing which version of the user's graph schema is currently in use. When a CREATE GRAPH statement is executed, the version is initialized to 0. Each time a SCHEMA_CHANGE JOB is run, the schema value is incremented (e.g., 1, 2, etc.).