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fix: allow duplicate column names in query responses #2623

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fix: allow duplicate column names in query responses #2623

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10 changes: 6 additions & 4 deletions client-v2/src/main/java/com/clickhouse/client/api/metadata/TableSchema.java
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,9 @@

import com.clickhouse.data.ClickHouseColumn;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;

import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

Expand All @@ -30,15 +30,17 @@ public TableSchema(String tableName, String query, String databaseName, Collecti
this.databaseName = databaseName;
this.query = query;
this.columns = ImmutableList.copyOf(columns);
ImmutableMap.Builder<String, Integer> colIndexMapBuilder = ImmutableMap.builder();
Map<String, Integer> colIndexMapBuilder = new HashMap<>();
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@chernser chernser Oct 25, 2025

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HashMap is much slower that ImmutableMap - that we have measured in our benchmark tests.
ImmutableMap allows to leave last value.

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@maxjustus maxjustus Oct 25, 2025

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got it!

for (int i = 0; i < this.columns.size(); i++) {
ClickHouseColumn column= this.columns.get(i);
if (column.hasDefault()) {
this.hasDefaults = true;
}
colIndexMapBuilder.put(this.columns.get(i).getColumnName(), i);
String columnName = column.getColumnName();
// if a column is duplicated, the last one wins
colIndexMapBuilder.put(columnName, i);
}
this.colIndex = colIndexMapBuilder.build();
this.colIndex = colIndexMapBuilder;
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@windsurf-bot windsurf-bot bot Oct 24, 2025

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The colIndex map is no longer immutable after switching from ImmutableMap to HashMap, but it's still exposed as a public field. Consider making this field private or ensuring it remains immutable by wrapping it with Collections.unmodifiableMap() to prevent external modifications.

}

/**
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