The HybridAnalyzer routes the unresolved logical plan between the legacy Analyzer and a single-pass Analyzer when the query that we are processing is being run from unit tests depending on the testing flags set and the structure of this unresolved logical plan:

• If the "spark.sql.analyzer.singlePassResolver.soloRunEnabled" is "true", the HybridAnalyzer will unconditionally run the single-pass Analyzer, which would usually result in some unexpected behavior and failures. This flag is used only for development.
• If the "spark.sql.analyzer.singlePassResolver.dualRunEnabled" is "true", the HybridAnalyzer will invoke the legacy analyzer and optionally _also_ the fixed-point one depending on the structure of the unresolved plan. This decision is based on which features are supported by the single-pass Analyzer, and the checking is implemented in the ResolverGuard. After that we validate the results using the following logic:
  • If the fixed-point Analyzer fails and the single-pass one succeeds, we throw an appropriate exception (please check the QueryCompilationErrors.fixedPointFailedSinglePassSucceeded method)
  • If both the fixed-point and the single-pass Analyzers failed, we throw the exception from the fixed-point Analyzer.
  • If the single-pass Analyzer failed, we throw an exception from its failure.
  • If both the fixed-point and the single-pass Analyzers succeeded, we compare the logical plans and output schemas, and return the resolved plan from the fixed-point Analyzer.
• Otherwise we run the legacy analyzer.