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Event Tap

Joule provides the ability to tap an event stream in to an in-process / memory database. This feature is useful to gain data in SQL format for addtional purposes such as off-line analytic. Combining this feature with the provided Rest API functionality it becomes a powerful feature.

Example

tap:
target schema: nasdaq_quotes
queue capacity: 15000
flush frequency: 5
index:
unique: false
fields:
- symbol

Attributes

Attribute
Description
Data Type
Required
target schema
Target table name
String
queue capacity
Number of events to queue before flushing to database.
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Must be greater than 99.
Integer
Default :10000
flush frequency
Frequency the queue is flushed to database table. Either the queue capacity or this attribute triggers queue flush whatever comes first.
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Must me greater than zereo.
Long
Default: 5 Seconds
alias
Alias to use instead of the schema name
String
is insert
Update or insert to apply to table changes
Boolean
Default: true
update criteria fields
Array of fields used for the update criteria predicate. Only used if is insert set to false
String[]
index
Create a table index
See Index attributes

Index Attributes

Attribute
Description
Data Type
Required
uniquie index
Create a unique index
Boolean
Default: false
index fields
Array of fields to create index
String[]

SQL Queries

On processor initialisation a set of queries are auto generated which are used to bind Rest API endpoints. The following queries are generated:

Select

Select data using pagnation either with or without an ingestTime date range.

Export

Ability to export the table either by CSV or Parquet formats.

Delete

Query to delete rows from the table between an ingestTime date range.
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