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- Allow expanding vertex fields within :code:`optional` scopes.
`83 <https://github.com/kensho-technologies/graphql-compiler/pull/83>`__
This is a massive feature, totaling over 4000 lines of changes and
hundreds of hours of many engineers' time. Special thanks to
:code:`amartyashankha` for taking point on the implementation!
This feature implements a workaround for a limitation of OrientDB, where
:code:`MATCH` treats optional vertices as terminal and does not allow
subsequent traversals from them. To work around this issue, the compiler
rewrites the query into several disjoint queries whose union produces
the exact same results as a single query that allows optional
traversals. See this `link <https://graphql-compiler.readthedocs.io/en/latest/supported_databases/orientdb.html#compound-optional-performance-penalty>`__
for more details.