sql: fix performance regression due to increased hash allocations

docs/generated/http/full.md

@@ -1813,7 +1813,7 @@ information about the resources on a node used by that table.
 | Field | Type | Label | Description |
 | ----- | ---- | ----- | ----------- |
 | key | [StatementsResponse.ExtendedStatementStatisticsKey](#cockroach.server.serverpb.StatementsResponse-cockroach.server.serverpb.StatementsResponse.ExtendedStatementStatisticsKey) |  |  |
-| id | [string](#cockroach.server.serverpb.StatementsResponse-string) |  |  |
+| id | [uint64](#cockroach.server.serverpb.StatementsResponse-uint64) |  |  |
 | stats | [cockroach.sql.StatementStatistics](#cockroach.server.serverpb.StatementsResponse-cockroach.sql.StatementStatistics) |  |  |
 
 

pkg/roachpb/app_stats.go

@@ -11,28 +11,34 @@
 package roachpb
 
 import (
-	"fmt"
-	"hash/fnv"
 	"math"
+
+	"github.com/cockroachdb/cockroach/pkg/util"
 )
 
 // StmtID is the type of a Statement ID.
-type StmtID string
+type StmtID uint64
 
 // ConstructStatementID constructs an ID by hashing an anonymized query, it's
 // failure status, and if it was part of an implicit txn. At the time of writing,
 // these are the axis' we use to bucket queries for stats collection
 // (see stmtKey).
 func ConstructStatementID(anonymizedStmt string, failed bool, implicitTxn bool) StmtID {
-	h := fnv.New128()
-	h.Write([]byte(anonymizedStmt))
+	fnv := util.MakeFNV64()
+	for _, c := range anonymizedStmt {
+		fnv.Add(uint64(c))
+	}
 	if failed {
-		h.Write([]byte("failed"))
+		fnv.Add('F')
+	} else {
+		fnv.Add('S')
 	}
 	if implicitTxn {
-		h.Write([]byte("implicit_txn"))
+		fnv.Add('I')
+	} else {
+		fnv.Add('E')
 	}
-	return StmtID(fmt.Sprintf("%x", h.Sum(nil)))
+	return StmtID(fnv.Sum())
 }
 
 // GetVariance retrieves the variance of the values.