Cleanup of TPC handling #32891
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Cleanup of TPC handling #32891
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roji
commented
Jan 22, 2024
| if (newList.Count > 0) | ||
| { | ||
| _tpcDiscriminatorValues[leftTpc] = (leftColumn, newList); | ||
| tpcExpression.DiscriminatorValues = newList; |
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Note that this is mutation, but it occurs in ApplyPredicate, when the whole SelectExpression is still in mutable state. If we end up making SelectExpression fully mutable always, we'll change this to produce a copy.
| @@ -47,8 +47,8 @@ SELECT COUNT(*) | |||
| UNION ALL | |||
| SELECT [k].[CountryId] | |||
| FROM [Kiwi] AS [k] | |||
| ) AS [t] | |||
| WHERE [t].[CountryId] = 1 AND [c].[Id] = [t].[CountryId] AND [t].[CountryId] > 0) > 0 | |||
| ) AS [u] | |||
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Test baselines are only alias changes from t to u (i.e. union).
AndriySvyryd
approved these changes
Jan 24, 2024
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Our current TPC design uses a special TableExpressionBase - TpcTablesExpression - to represent the potential set of table queries that will be needed. In postprocessing, TpcTablesExpressionRemovingExpressionVisitor reduces TpcTablesExpression to actual unioned subqueries, based on the concrete entity types that are actually needed.
This refactor does two main things:
_tpcDiscriminatorValuesfrom SelectExpression. This was private state which specified - for each TpcTablesExpression contained in the SelectExpression - the discriminator column and actual needed discriminator values. This information was moved onto TpcTablesExpression itself.