31 lines
940 B
Python
31 lines
940 B
Python
from sqlglot import alias, exp
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from sqlglot.errors import OptimizeError
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from sqlglot.optimizer.scope import traverse_scope
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def isolate_table_selects(expression):
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for scope in traverse_scope(expression):
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if len(scope.selected_sources) == 1:
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continue
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for (_, source) in scope.selected_sources.values():
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if not isinstance(source, exp.Table):
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continue
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if not isinstance(source.parent, exp.Alias):
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raise OptimizeError(
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"Tables require an alias. Run qualify_tables optimization."
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)
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parent = source.parent
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parent.replace(
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exp.select("*")
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.from_(
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alias(source, source.name or parent.alias, table=True),
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copy=False,
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)
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.subquery(parent.alias, copy=False)
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)
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return expression
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