Implement Connection.GetSchema

[hazzik]

This PR implements Connection.GetSchema.

Standard collections:
✔️ MetaDataCollections
✔️ Restrictions
✔️ ReservedWords
❌ DataSourceInformation
❌ DataTypes

Non standard common collections
✔️ Tables
✔️ Columns
✔️ ForeignKeys
✔️ Indexes

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.41%. Comparing base (6270bac) to head (1033016).
Report is 35 commits behind head on develop.

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Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #185      +/-   ##
===========================================
+ Coverage    87.83%   88.41%   +0.58%     
===========================================
  Files           42       54      +12     
  Lines         1504     1761     +257     
  Branches       217      239      +22     
===========================================
+ Hits          1321     1557     +236     
- Misses         127      146      +19     
- Partials        56       58       +2     

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[coveralls]

Pull Request Test Coverage Report for Build 9155702909

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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Details

• 121 of 121 (100.0%) changed or added relevant lines in 2 files are covered.
• 8 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.7%) to 90.216%

---

Files with Coverage Reduction	New Missed Lines	%
DuckDB.NET.Data/DuckDBCommand.cs	1	89.83%
DuckDB.NET.Data/Internal/Reader/VectorDataReaderBase.cs	1	88.27%
DuckDB.NET.Data/Internal/PreparedStatement.cs	3	93.33%
DuckDB.NET.Data/Internal/Reader/DateTimeVectorDataReader.cs	3	90.2%

Totals
Change from base Build 9119577775:	0.7%
Covered Lines:	1615
Relevant Lines:	1761

---

💛 - Coveralls

[Giorgi]

Is it still WIP?

[hazzik]

Yes, want to implement a few more essential collections.

[Giorgi]

I'll mark it as Draft. Please mark it ready for review when it's finished. Thanks

[hazzik]

Ok. This is ready for review now. I've implemented almost all metadata I wanted, except IndexColumns, that seems to be impossible to implement. Also, I have not implemented DataTypes and DataSourceInformation standard collections as I don't have interest in them. If that's is required it would be possible to implement later.

[Giorgi]

Thanks, I'll try to review it in the next few days. Is there any documentation on how GetSchema should work and what kind of structure it should return?

[hazzik]

The documentation is really loose, the basic description of how it should work is here: https://learn.microsoft.com/en-us/dotnet/framework/data/adonet/retrieving-database-schema-information.

With common schema collections and custom collections that are available via informational_schema catalog it is more-or-less settled, but for custom collections it becomes trickier (in context of this PR it is only Indexes collection): the column names and information do not often match between providers.

[Giorgi]

Thanks, looks good! Left some minor comments.

[Giorgi]

What do these numbers mean? Can you add a comment?

[hazzik]

This is from columns definition above:

                { DbMetaDataColumnNames.CollectionName, typeof(string) },
                { DbMetaDataColumnNames.NumberOfRestrictions, typeof(int) },
                { DbMetaDataColumnNames.NumberOfIdentifierParts, typeof(int) }

[Giorgi]

What do the numbers 4 and 3 refer too?

[hazzik]

The first number says how many restrictions could the collection have (it is about restrictionValues/restrictionNames arrays). The last number is purely for information purposes. It says that index has 3 components in its full name: catalog.schema.index_name.

[Giorgi]

If the numbers above refer to the length of these arrays, can you extract these arrays somewhere and refer to their Length in GetMetaDataCollections ?

[hazzik]

If the numbers above refer to the length of these arrays

Yes,

can you extract these arrays somewhere and refer to their Length in GetMetaDataCollections

I could, try, but it would just complicate the code, I afraid, without providing any benefit.

[Giorgi]

Thanks, merged.

[hazzik]

Thank you

[Giorgi]

@hazzik This is now live on NuGet.