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Module query_columns

Module query_columns 

Source
Expand description

Column-oriented query results that keep the query’s column order.

The connectors used to hand back HashMap<String, Vec<String>>, which has no order at all: SELECT a, b FROM t could profile as ["b", "a"], and hash iteration is not even stable between processes, so two runs of the same query could disagree. Every other input path reports columns in source order — CSV header order, Parquet schema order, JSON first-seen field order — so the database path was the one place where a format conversion reshuffled a report.

QueryColumns is that map with the order kept: a vector of named columns, built in the order the driver reports them.

Structs§

QueryColumns
A query result as columns, in the order the query selected them.

Functions§

merge_column_batches
Merge batches of a streamed query into one result.