Textual and Visual Algebra Exploration

[tobias-weber]

Summary

This PR enhances Polypheny with the ability to serialize arbitrary query plans into a textual representation called PolyAlgebra. This is the foundation for the new framework-based plan editor system in the UI. The required functionality is provided via new HTTP endpoints and websocket messages.

Changes

• Removed the old query plan builder

• Replaced the old InformationQueryPlan with InformationPolyAlg for the new plan editor

• Changed the order of information pages for executed queries to be grouped by statements

• Added Optional for multiple cost and count metadata @datomo

• Changed CyclicMetadataException to follow GenericRuntimeException @datomo

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Features

• Ability to serialize AlgNodes to PolyAlgebra (textual or structured representation)
• Parser for reconstructing the AlgNodes from PolyAlgebra
• Directly execute logical / allocation / physical plans specified in PolyAlgebra
• Supported AlgNodes:
  • all logical AlgNodes
  • for physical: Enumerable and Jdbc (can be used as reference implementation for the remaining AlgNodes)

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Tests

• PolyAlgParsingTest: verifying consistent serialization and reconstruction of query plans for various queries

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ToDo

• Actions do not yet run successfully. Locally, all tests succeed...
• @datomo Fix return type inference for CYPHER_EXTRACT_FROM_PATH, then enable corresponding tests in PolyAlgParsingTest
• Register all remaining physical AlgNodes (register declaration, implement bindArguments() and static create() method). This can also be done at a later point, as it is only required for the rare use case of editing physical plans.

[datomo]

This look good to me (except the sometimes single failing tests...)!