From 618b1c113c1c21b21d0a2a09dcc1b057ace06c5c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9D=A8=E6=9D=B0?= <zdyj3170101136@gmail.com>
Date: Thu, 19 Sep 2024 16:46:13 +0800
Subject: [PATCH] perf(col_low_cardinality): use small value

---
 proto/col_low_cardinality.go | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/proto/col_low_cardinality.go b/proto/col_low_cardinality.go
index ffed5809..38f3bff1 100644
--- a/proto/col_low_cardinality.go
+++ b/proto/col_low_cardinality.go
@@ -286,17 +286,6 @@ func (c ColLowCardinality[T]) Rows() int {
 
 // Prepare column for ingestion.
 func (c *ColLowCardinality[T]) Prepare() error {
-	// Select minimum possible size for key.
-	if n := len(c.Values); n < math.MaxUint8 {
-		c.key = KeyUInt8
-	} else if n < math.MaxUint16 {
-		c.key = KeyUInt16
-	} else if uint32(n) < math.MaxUint32 {
-		c.key = KeyUInt32
-	} else {
-		c.key = KeyUInt64
-	}
-
 	// Allocate keys slice.
 	c.keys = append(c.keys[:0], make([]int, len(c.Values))...)
 	if c.kv == nil {
@@ -317,6 +306,17 @@ func (c *ColLowCardinality[T]) Prepare() error {
 		c.keys[i] = idx
 	}
 
+	// Select minimum possible size for key.
+	if n := last; n < math.MaxUint8 {
+		c.key = KeyUInt8
+	} else if n < math.MaxUint16 {
+		c.key = KeyUInt16
+	} else if uint32(n) < math.MaxUint32 {
+		c.key = KeyUInt32
+	} else {
+		c.key = KeyUInt64
+	}
+
 	// Fill key column with key indexes.
 	switch c.key {
 	case KeyUInt8: