From fbe67ce0514e290bf5695e3b7b84ae01e57a3bc7 Mon Sep 17 00:00:00 2001
From: Yahor Yuzefovich <yahor@cockroachlabs.com>
Date: Fri, 7 Nov 2025 11:26:00 -0800
Subject: [PATCH] sql: speed up recently added TestTruncateLarge

We just saw a timeout in tests where 15m limit was exceeded because more
than 11m were consumed by TestTruncateLarge. In order to speed up the
test, this commit reduces the number of tables affected as well as
splits up two sub-tests into separate tests (hoping that they will end
up in different shards).

Release note: None
---
 pkg/sql/drop_test.go | 74 +++++++++++++++++++++++++-------------------
 1 file changed, 42 insertions(+), 32 deletions(-)

diff --git a/pkg/sql/drop_test.go b/pkg/sql/drop_test.go
index 04677df43adc..12b164422cb6 100644
--- a/pkg/sql/drop_test.go
+++ b/pkg/sql/drop_test.go
@@ -1557,42 +1557,52 @@ func TestDropLargeDatabaseWithDeclarativeSchemaChanger(t *testing.T) {
 func TestTruncateLarge(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
-	skip.UnderDuress(t, "truncating a large number of tables")
+	testTruncateLarge(t, true /* batchLimitSet */)
+}
 
-	testutils.RunTrueAndFalse(t, "batch limit set", func(t *testing.T, batchLimitSet bool) {
-		ctx := context.Background()
-		srv, conn, _ := serverutils.StartServer(t, base.TestServerArgs{})
-		defer srv.Stopper().Stop(ctx)
-		sqlDB := sqlutils.MakeSQLRunner(conn)
-		createCommand := strings.Builder{}
-		truncateCommand := strings.Builder{}
-		systemDB := sqlutils.MakeSQLRunner(srv.SystemLayer().SQLConn(t))
-		systemDB.Exec(t, "SET CLUSTER SETTING kv.raft.command.max_size='5m'")
-		if batchLimitSet {
-			sqlDB.Exec(t, "SET CLUSTER SETTING sql.schema_changer.batch_flush_threshold_size='2m'")
-		}
-		// Generate the truncate and create table commands.
-		const numTables = 500
-		truncateCommand.WriteString("TRUNCATE TABLE ")
-		for i := range numTables {
-			createCommand.WriteString(fmt.Sprintf("CREATE TABLE t%d (a INT PRIMARY KEY, j INT, k INT, INDEX (j), INDEX (k), UNIQUE (j, k));\n", i))
-			truncateCommand.WriteString(fmt.Sprintf("t%d", i))
-			if i != numTables-1 {
-				truncateCommand.WriteString(", ")
-			}
-		}
-		// Execute the create commands first.
-		sqlDB.Exec(t, createCommand.String())
+// TestTruncateLargeErr verifies that an error is returned if the batch limit is
+// effectively not set.
+func TestTruncateLargeErr(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	defer log.Scope(t).Close(t)
+	testTruncateLarge(t, false /* batchLimitSet */)
+}
 
-		// The default limit is larger than our reduced raft command size, so if the
-		// limit is not modified, the truncate command will fail.
-		if batchLimitSet {
-			sqlDB.Exec(t, truncateCommand.String())
-		} else {
-			sqlDB.ExpectErr(t, "command is too large", truncateCommand.String())
-		}
+func testTruncateLarge(t *testing.T, batchLimitSet bool) {
+	skip.UnderDuress(t, "truncating a large number of tables")
+
+	srv, conn, _ := serverutils.StartServer(t, base.TestServerArgs{
+		SQLMemoryPoolSize: 1 << 30, /* 1 GiB */
 	})
+	defer srv.Stopper().Stop(context.Background())
+	sqlDB := sqlutils.MakeSQLRunner(conn)
+	createCommand := strings.Builder{}
+	truncateCommand := strings.Builder{}
+	systemDB := sqlutils.MakeSQLRunner(srv.SystemLayer().SQLConn(t))
+	systemDB.Exec(t, "SET CLUSTER SETTING kv.raft.command.max_size='4.1MiB'")
+	if batchLimitSet {
+		sqlDB.Exec(t, "SET CLUSTER SETTING sql.schema_changer.batch_flush_threshold_size='1.8MiB'")
+	}
+	// Generate the truncate and create table commands.
+	const numTables = 340
+	truncateCommand.WriteString("TRUNCATE TABLE ")
+	for i := range numTables {
+		createCommand.WriteString(fmt.Sprintf("CREATE TABLE t%d (a INT PRIMARY KEY, j INT, k INT, INDEX (j), INDEX (k), UNIQUE (j, k));\n", i))
+		truncateCommand.WriteString(fmt.Sprintf("t%d", i))
+		if i != numTables-1 {
+			truncateCommand.WriteString(", ")
+		}
+	}
+	// Execute the create commands first.
+	sqlDB.Exec(t, createCommand.String())
 
+	// The default limit is larger than our reduced raft command size, so if the
+	// limit is not modified, the truncate command will fail.
+	if batchLimitSet {
+		sqlDB.Exec(t, truncateCommand.String())
+	} else {
+		sqlDB.ExpectErr(t, "command is too large", truncateCommand.String())
+	}
 }
 
 func BenchmarkDropLargeDatabaseWithGenerateTestObjects(b *testing.B) {