Views:

Luminesce queries are written in the SQL dialect of SQLite, with the syntactical extensions and limitations described below. See which tools are available to write queries.

Note a query can be written either for a data provider or a direct provider, and there are some syntactical differences between them. In particular, direct providers have an arbitrary syntax that may differ for each.

Summary

Luminesce supports most of the syntax of the SQLite SELECT statement. It does not support data definition language (DDL) syntax for creating or modifying database objects.

  • Common table expressions (CTE) are not supported in Luminesce SELECT statements but a re-usable variable syntax is available instead.
  • TYPES statements can be used before Luminesce SELECT statements to force type conversion on columns.
  • FOR-EACH loops can be emulated using APPLY statements.
  • A WAIT modifier is available to pause query execution.
  • A number of common SQL functions are supported, and we've supplemented these with sets of custom functions and statistical functions.
  • A number of PRAGMA statements specific to Luminesce are supported.
  • Dates must be encapsulated in # rather than ' characters, so for example #yyyy-MM-dd HH:mm:ss#
  • Strings must be encapsulated in ' rather than " characters, so for example where PortfolioScope = 'Finbourne-Examples'
  • Multiple lines can be commented out using /* and */ characters at the beginning and end respectively.
SELECT statement examplesExplanation
select * from Some.ProviderSelects all the columns from Some.Provider
select x, y from Some.ProviderSelects the X and Y columns
select * (except x, y) from Some.ProviderSelects all the columns except X and Y. Can use the - character in place of except
select ^ from Some.ProviderSelects the main columns (those considered most important by the provider author)
select ^ (except x, y) from Some.ProviderSelects the main columns except X and Y
select * from Some.Provider limit 5Returns only the first 5 records

For a Some.Provider that is authored by Finbourne, the fields (columns) available to return or filter can be determined by running the following query:

select FieldName, DataType, IsMain, IsPrimaryKey, SampleValues, Description from Sys.Field where TableName = 'Some.Provider' and FieldType = 'Column';

Parameters

Data providers may have parameters that can be used to filter a Luminesce query as part of a standard WHERE clause.

Note: Direct providers do not support parameters.

You must assign values to parameters unambiguously (not under an OR clause), and only with the = operator. For example:

select * from Some.Provider where SomeParameter = 12
 

For a Some.Provider that is authored by Finbourne, available parameters can be determined by running the following query:

select FieldName, DataType, ParamDefaultValue, Description from Sys.Field where TableName = 'Some.Provider' and FieldType = 'Parameter';

Variables

You can use variables to create and populate arbitrary tables of data that can then be used as part of a Luminesce query for either a data provider or a direct provider.

This is similar to a combination of the standard SQL CREATE TABLE...INSERT INTO statements.

Variable typeExplanationExamples
@tablevariableStores a table of any size@abc = select TableName, FieldName from Sys.Field order by 1, 2;
@@scalarvariableOnly stores a scalar value (that is, the SELECT statement must resolve to exactly one column and one row of data)@@abc = select strftime('%Y%m%d', 'now');
@@portfolioscope = select 'Finbourne-Examples';

Type conversion

You can use the TYPES statement before any SELECT statement in a Luminesce query to force type conversion on columns.

Valid types are BIGINT, INT, DOUBLE, DECIMAL, BOOLEAN, TEXT, DATE, TIME and DATETIME.

ExampleExplanation
TYPES bigint, int, text, boolean;
SELECT 1, 2, 3, 4;
Returns columns as Int64, Int32, String and Boolean types respectively.
TYPES bigint, int, , boolean;
SELECT 1, 2, 3, 4;
Returns columns 1, 2 and 4 as Int64, Int32 and Boolean types respectively. The data type of column 3 would be inferred in the normal way.
TYPES double;
SELECT SUM(Cost) as X FROM Products;
Returns the result of the aggregate function as a double.

FOR-EACH loops

You can use the CROSS APPLY or OUTER APPLY statement to emulate a FOR-EACH loop. This is useful to execute a Luminesce query in parallel on a range of parameter inputs.

APPLY statementExplanation
CROSS APPLYSimilar to INNER JOIN, in that only records that have matching values on both sides are returned. 
OUTER APPLYSimilar to LEFT OUTER JOIN, in that all records on the left side are returned, even when there are no matching records on the right side.

Note: There is no ON clause for either APPLY statement.

For example, the following query uses OUTER APPLY to calculate holdings for the last 3 days:

@days = select date('now', '-' || Value || ' days') as dt
from Tools.[Range] where number = 3   -- go back N days from today
and Start = 0;                        -- subtract 0 days, to include today (1 would exclude today)

select d.dt, results.*
from @days d
outer apply (
       select h.^
       from lusid.portfolio.holding h
       where h.EffectiveAt = d.dt and h.PortfolioCode = 'test-portfolio'
) results;
 

Note: You must alias all tables inside the SELECT statement of a CROSS APPLY or OUTER APPLY statement (in the example above, h is the alias for the table returned by the Lusid.Portfolio.Holding provider).

Pausing query execution

You can use the WAIT modifier at any point in a query to wait for all the preceding code to execute before continuing, and optionally for a further specified number of seconds.

For example, if you delete a view in order to change its behavior you might want to wait 5 seconds before creating it again:

@x = use Sys.Admin.SetupView
--provider=Test.Example.TestHoldings
--deleteProvider

----
select 1 as deleting
enduse;
-- Wait 5 seconds after delete before executing rest of query
select from @x wait 5;
...

PRAGMA statements

You can use the PRAGMA statements in the following table to override default Luminesce settings for a particular query. For example, to allow a query to run for 30 minutes before timing out, specify:

pragma TimeoutSec = 1800;
 
PRAGMAExplanation
MaxApplyParallelization = <number>Defines the maximum number of parallel provider calls within a CROSS APPLY or OUTER APPLY statement in a query. Defaults to 5.
TimeoutSec = <seconds>Specifies a number of seconds to wait before a query times out.
QueryName = <name>Names a query.
TypeDeterminationRowCount = <rows>Specifies the number of rows to use to determine the data type on returned data sets (defaults to 500). Note that for views it is better to prefer the ~<DataType> syntax.
WebApiCacheForSeconds = <seconds>For use with the Luminesce /api/SqlBackground/* REST APIs in the Sql Background Execution collection. Re-uses the results from a previous character-identical query for up to the number of seconds when run by the same user. This must be specified on the 1st and 2nd+ usages of the query.