fix: restore reviewable migration evidence

db/migrate.go

@@ -0,0 +1,134 @@
+package db
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/ClickHouse/clickhouse-go/v2"
+)
+
+const schemaSQL = `
+CREATE TABLE IF NOT EXISTS proxy_logs (
+    request_id String,
+    method String,
+    path String,
+    query String,
+    client_ip String,
+    request_headers String,
+    request_body String,
+    request_truncated Bool DEFAULT false,
+    status_code Int32,
+    response_headers String,
+    response_body String,
+    response_truncated Bool DEFAULT false,
+    is_stream Bool DEFAULT false,
+    latency_ms Int64,
+    started_at DateTime64(3),
+    finished_at DateTime64(3),
+    error String
+)
+ENGINE = MergeTree
+PARTITION BY toYYYYMM(started_at)
+ORDER BY (started_at, request_id)
+`
+
+func migrate(ctx context.Context, conn clickhouse.Conn) error {
+	if err := conn.Exec(ctx, schemaSQL); err != nil {
+		return fmt.Errorf("create proxy_logs: %w", err)
+	}
+
+	rows, err := conn.Query(ctx, `
+SELECT name, type
+FROM system.columns
+WHERE database = currentDatabase() AND table = 'proxy_logs'
+ORDER BY position`)
+	if err != nil {
+		return fmt.Errorf("query proxy_logs columns: %w", err)
+	}
+	var columns []schemaColumn
+	for rows.Next() {
+		var column schemaColumn
+		if err := rows.Scan(&column.name, &column.typ); err != nil {
+			rows.Close()
+			return fmt.Errorf("scan proxy_logs columns: %w", err)
+		}
+		columns = append(columns, column)
+	}
+	if err := rows.Err(); err != nil {
+		rows.Close()
+		return fmt.Errorf("read proxy_logs columns: %w", err)
+	}
+	rows.Close()
+
+	var table schemaTable
+	err = conn.QueryRow(ctx, `
+SELECT engine, partition_key, sorting_key
+FROM system.tables
+WHERE database = currentDatabase() AND name = 'proxy_logs'`).Scan(
+		&table.engine, &table.partitionKey, &table.sortingKey,
+	)
+	if err != nil {
+		return fmt.Errorf("query proxy_logs table: %w", err)
+	}
+	if err := validateProxyLogsSchema(columns, table); err != nil {
+		return fmt.Errorf("incompatible proxy_logs schema: %w", err)
+	}
+	return nil
+}
+
+type schemaColumn struct {
+	name string
+	typ  string
+}
+
+type schemaTable struct {
+	engine       string
+	partitionKey string
+	sortingKey   string
+}
+
+var proxyLogsColumns = []schemaColumn{
+	{"request_id", "String"},
+	{"method", "String"},
+	{"path", "String"},
+	{"query", "String"},
+	{"client_ip", "String"},
+	{"request_headers", "String"},
+	{"request_body", "String"},
+	{"request_truncated", "Bool"},
+	{"status_code", "Int32"},
+	{"response_headers", "String"},
+	{"response_body", "String"},
+	{"response_truncated", "Bool"},
+	{"is_stream", "Bool"},
+	{"latency_ms", "Int64"},
+	{"started_at", "DateTime64(3)"},
+	{"finished_at", "DateTime64(3)"},
+	{"error", "String"},
+}
+
+func validateProxyLogsSchema(columns []schemaColumn, table schemaTable) error {
+	if len(columns) != len(proxyLogsColumns) {
+		return fmt.Errorf("got %d columns, want %d", len(columns), len(proxyLogsColumns))
+	}
+	for i, want := range proxyLogsColumns {
+		if columns[i] != want {
+			return fmt.Errorf("column %d is %s %s, want %s %s", i+1, columns[i].name, columns[i].typ, want.name, want.typ)
+		}
+	}
+	if table.engine != "MergeTree" {
+		return fmt.Errorf("engine is %q, want MergeTree", table.engine)
+	}
+	if compactExpression(table.partitionKey) != "toYYYYMM(started_at)" {
+		return fmt.Errorf("partition key is %q, want toYYYYMM(started_at)", table.partitionKey)
+	}
+	if compactExpression(table.sortingKey) != "started_at,request_id" {
+		return fmt.Errorf("sorting key is %q, want started_at, request_id", table.sortingKey)
+	}
+	return nil
+}
+
+func compactExpression(value string) string {
+	return strings.Join(strings.Fields(value), "")
+}