Business keys are mandatory with MS SQL Server

[janihaglund]

One must set uniqueBusinessKey for <bpm:process-factory /> as MS SQL Server doesn't allow multiple NULL values on unique indexes.

These issue can be reproduced by running test for https://github.com/alfameCom/mule-bpm-module/tree/mssql-verification/examples/passive-splitter-example

[janihaglund]

Updated on this issue.

It seems this can be overcome by creating index as follows:
CREATE UNIQUE INDEX MULE_UNIQ_BUSINESS_KEY ON ACT_HI_PROCINST(BUSINESS_KEY_) WHERE BUSINESS_KEY_ IS NOT NULL

In stead of the default implementation in place now https://github.com/alfameCom/mule-bpm-module/blob/mssql-verification/mule-bpm-module/src/main/resources/db/mule-bpm-flowable/migrations/V2__Insert_unique_process_instance_constrant.sql

Flyway V3 with SQL Server specific alter implementation should be implemented.

Additional notice on H2 MS SQL Server comparability mode: the filtered index above does not work. Testing with https://www.testcontainers.org/modules/databases/mssqlserver/ seems to be the next step.