From d10bf9f4ae98002c0f744ed8e8c0f266ea6af26d Mon Sep 17 00:00:00 2001
From: James Sherwood-Jones <james.sherwood-jones@gopigment.com>
Date: Wed, 7 Oct 2026 14:45:44 +0100
Subject: [PATCH] pkg/clickhouse: append column number for each line

The Line struct has six child columns. The ClickHouse querier did not
write to ColumnNumber. The column stayed shorter than the Line struct,
and Arrow panicked with "index out of range" when it built the record.

Append 0 to ColumnNumber for each line, as the parcacol writers do.
Add a test that builds a record from stored function data.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
---
 pkg/clickhouse/querier.go      |  2 +
 pkg/clickhouse/querier_test.go | 98 ++++++++++++++++++++++++++++++++++
 2 files changed, 100 insertions(+)
 create mode 100644 pkg/clickhouse/querier_test.go

diff --git a/pkg/clickhouse/querier.go b/pkg/clickhouse/querier.go
index 96716c7b235..8edae37134a 100644
--- a/pkg/clickhouse/querier.go
+++ b/pkg/clickhouse/querier.go
@@ -1002,6 +1002,7 @@ func (q *Querier) rowsToArrowRecords(
 				for _, line := range symbolizedLoc.Lines {
 					w.Line.Append(true)
 					w.LineNumber.Append(line.Line)
+					w.ColumnNumber.Append(0) // Column info is not available from symbolized locations.
 					if line.Function != nil {
 						if err := w.FunctionName.Append([]byte(line.Function.Name)); err != nil {
 							level.Error(q.logger).Log("msg", "failed to append function name", "err", err)
@@ -1025,6 +1026,7 @@ func (q *Querier) rowsToArrowRecords(
 				w.Lines.Append(true)
 				w.Line.Append(true)
 				w.LineNumber.Append(s.lineNumbers[idx])
+				w.ColumnNumber.Append(0) // Column info is not stored in ClickHouse.
 				if err := w.FunctionName.Append([]byte(s.functionNames[idx])); err != nil {
 					level.Error(q.logger).Log("msg", "failed to append function name", "err", err)
 				}
diff --git a/pkg/clickhouse/querier_test.go b/pkg/clickhouse/querier_test.go
new file mode 100644
index 00000000000..a21d6e9864c
--- /dev/null
+++ b/pkg/clickhouse/querier_test.go
@@ -0,0 +1,98 @@
+// Copyright 2024-2026 The Parca Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package clickhouse
+
+import (
+	"context"
+	"testing"
+
+	"github.com/apache/arrow-go/v18/arrow/memory"
+	"github.com/go-kit/log"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/otel/trace/noop"
+
+	"github.com/parca-dev/parca/pkg/symbolizer"
+)
+
+type fakeRows struct {
+	rows []sampleData
+	pos  int
+}
+
+func (f *fakeRows) Next() bool {
+	f.pos++
+	return f.pos <= len(f.rows)
+}
+
+func (f *fakeRows) Err() error { return nil }
+
+func (f *fakeRows) Scan(dest ...interface{}) error {
+	s := f.rows[f.pos-1]
+	*dest[0].(*[]uint64) = s.addresses
+	*dest[1].(*[]uint64) = s.mappingStarts
+	*dest[2].(*[]uint64) = s.mappingLimits
+	*dest[3].(*[]uint64) = s.mappingOffsets
+	*dest[4].(*[]string) = s.mappingFiles
+	*dest[5].(*[]string) = s.mappingBuildIDs
+	*dest[6].(*[]int64) = s.lineNumbers
+	*dest[7].(*[]string) = s.functionNames
+	*dest[8].(*[]string) = s.functionSystemNames
+	*dest[9].(*[]string) = s.functionFilenames
+	*dest[10].(*[]int64) = s.functionStartLines
+	*dest[11].(*int64) = s.value
+	*dest[12].(*string) = s.labelsJSON
+	*dest[13].(*int64) = s.duration
+	*dest[14].(*int64) = s.period
+	return nil
+}
+
+type noopSymbolizer struct{}
+
+func (noopSymbolizer) Symbolize(context.Context, symbolizer.SymbolizationRequest) error {
+	return nil
+}
+
+func TestRowsToArrowRecordsStoredFunctions(t *testing.T) {
+	mem := memory.NewCheckedAllocator(memory.NewGoAllocator())
+	defer mem.AssertSize(t, 0)
+
+	q := &Querier{
+		logger:     log.NewNopLogger(),
+		tracer:     noop.NewTracerProvider().Tracer("test"),
+		mem:        mem,
+		symbolizer: noopSymbolizer{},
+	}
+
+	rows := &fakeRows{rows: []sampleData{{
+		addresses:           []uint64{0x1, 0x2},
+		mappingStarts:       []uint64{0, 0},
+		mappingLimits:       []uint64{0, 0},
+		mappingOffsets:      []uint64{0, 0},
+		mappingFiles:        []string{"a", "a"},
+		mappingBuildIDs:     []string{"", ""},
+		lineNumbers:         []int64{10, 20},
+		functionNames:       []string{"foo", "bar"},
+		functionSystemNames: []string{"foo", "bar"},
+		functionFilenames:   []string{"foo.go", "bar.go"},
+		functionStartLines:  []int64{1, 2},
+		value:               1,
+		period:              1,
+	}}}
+
+	records, err := q.rowsToArrowRecords(context.Background(), rows, false)
+	require.NoError(t, err)
+	require.Len(t, records, 1)
+	defer records[0].Release()
+	require.EqualValues(t, 1, records[0].NumRows())
+}