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I suggest to remove providers, packages, titles, resources tables. Because we already have record_id and record_type columns in tags table.
One addition is to include credentials_id column to tags

Code Refactoring:

We use a lot of joins to retrieve records by tags. But now we can retrieve records from one table.

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Jira Legacy
server System JiraJIRA columnIds issuekey,summary,issuetype,created,updated,duedate,assignee,reporter,priority,status,resolution columns key,summary,type,created,updated,due,assignee,reporter,priority,status,resolution serverId 01505d01-b853-3c2e-90f1-ee9b165564fc key MSEARCH-429

We use a lot of joins to retrieve records by tags. But now we can retrieve records from one table.

• Write databaseChangeLog script to edit database structure
• Delete repositories related removed tables PackageRepository, ResourceRepository, TitleRepository, ProviderRepository
  
• Implement logic in TagsRepository to retrieve records from tags table by TagFilter
• Unit tests refactoring 

Changes advantages:

• Remove unused data, simplify database structure
• Get rid of code duplications, so searching by tag logic will be in the one class. Instead of 4 same classes
• Will stop using SQL Joiners to improve module response time when searching by tags.

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