randgen: add PopulateTableWithRandomData

PopulateRandTable populates the caller's table with random data. This helper
function aims to make it easier for engineers to develop randomized tests that
leverage randgen / sqlsmith.

I considered adding random insert statements into sqlsmith's randtables setup,
however the high probably of a faulty insert statement would cause the whole
setup to fail. See #75159

In the future, I'd like to develop a new helper function
PopulateDatabaseWithRandData which calls PopulateTableWithRandData on each
table in the order of the fk dependency graph.

Informs #72345

Release note: None

pkg/internal/sqlsmith/setup.go

@@ -103,9 +103,6 @@ func randTablesN(r *rand.Rand, n int) string {
 		sb.WriteString(stmt.String())
 		sb.WriteString(";\n")
 	}
-
-	// TODO(mjibson): add random INSERTs.
-
 	return sb.String()
 }
 

pkg/sql/randgen/BUILD.bazel

@@ -49,7 +49,23 @@ go_library(
 
 go_test(
     name = "randgen_test",
-    srcs = ["mutator_test.go"],
+    srcs = [
+        "main_test.go",
+        "mutator_test.go",
+        "schema_test.go",
+    ],
     embed = [":randgen"],
-    deps = ["//pkg/util/randutil"],
+    deps = [
+        "//pkg/base",
+        "//pkg/security",
+        "//pkg/security/securitytest",
+        "//pkg/server",
+        "//pkg/sql/sem/tree",
+        "//pkg/testutils/serverutils",
+        "//pkg/testutils/sqlutils",
+        "//pkg/testutils/testcluster",
+        "//pkg/util/leaktest",
+        "//pkg/util/randutil",
+        "@com_github_stretchr_testify//require",
+    ],
 )

pkg/sql/randgen/main_test.go

@@ -0,0 +1,33 @@
+// Copyright 2019 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package randgen
+
+import (
+	"os"
+	"testing"
+
+	"github.com/cockroachdb/cockroach/pkg/security"
+	"github.com/cockroachdb/cockroach/pkg/security/securitytest"
+	"github.com/cockroachdb/cockroach/pkg/server"
+	"github.com/cockroachdb/cockroach/pkg/testutils/serverutils"
+	"github.com/cockroachdb/cockroach/pkg/testutils/testcluster"
+	"github.com/cockroachdb/cockroach/pkg/util/randutil"
+)
+
+//go:generate ../../util/leaktest/add-leaktest.sh *_test.go
+
+func TestMain(m *testing.M) {
+	security.SetAssetLoader(securitytest.EmbeddedAssets)
+	randutil.SeedForTests()
+	serverutils.InitTestServerFactory(server.TestServerFactory)
+	serverutils.InitTestClusterFactory(testcluster.TestClusterFactory)
+	os.Exit(m.Run())
+}

pkg/sql/randgen/mutator_test.go

@@ -14,10 +14,12 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
 	"github.com/cockroachdb/cockroach/pkg/util/randutil"
 )
 
 func TestPostgresMutator(t *testing.T) {
+	defer leaktest.AfterTest(t)()
 	q := `
 		CREATE TABLE t (s STRING FAMILY fam1, b BYTES, FAMILY fam2 (b), PRIMARY KEY (s ASC, b DESC), INDEX (s) STORING (b))
 		    PARTITION BY LIST (s)

pkg/sql/randgen/schema.go

@@ -20,6 +20,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog"
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/colinfo"
+	"github.com/cockroachdb/cockroach/pkg/sql/parser"
 	"github.com/cockroachdb/cockroach/pkg/sql/rowenc"
 	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
@@ -186,6 +187,138 @@ func RandCreateTableWithColumnIndexNumberGenerator(
 	return res[0].(*tree.CreateTable)
 }
 
+func parseCreateStatement(createStmtSQL string) (*tree.CreateTable, error) {
+	var p parser.Parser
+	stmts, err := p.Parse(createStmtSQL)
+	if err != nil {
+		return nil, err
+	}
+	if len(stmts) != 1 {
+		return nil, errors.Errorf("parsed CreateStatement string yielded more than one parsed statment")
+	}
+	tableStmt, ok := stmts[0].AST.(*tree.CreateTable)
+	if !ok {
+		return nil, errors.Errorf("AST could not be cast to *tree.CreateTable")
+	}
+	return tableStmt, nil
+}
+
+// generateInsertStmtVals generates random data for a string builder thats
+// used after the VALUES keyword in an INSERT statement.
+func generateInsertStmtVals(rng *rand.Rand, colTypes []*types.T, nullable []bool) string {
+	var valBuilder strings.Builder
+	valBuilder.WriteString("(")
+	comma := ""
+	for j := 0; j < len(colTypes); j++ {
+		valBuilder.WriteString(comma)
+		var d tree.Datum
+		if rand.Intn(10) < 4 {
+			// 40% of the time, use a corner case value
+			d = randInterestingDatum(rng, colTypes[j])
+		}
+		if colTypes[j] == types.RegType {
+			// RandDatum is naive to the constraint that a RegType < len(types.OidToType),
+			// at least before linking and user defined types are added.
+			d = tree.NewDOid(tree.DInt(rand.Intn(len(types.OidToType))))
+		}
+		if d == nil {
+			d = RandDatum(rng, colTypes[j], nullable[j])
+		}
+		valBuilder.WriteString(tree.AsStringWithFlags(d, tree.FmtParsable))
+		comma = ", "
+	}
+	valBuilder.WriteString(")")
+	return valBuilder.String()
+}
+
+// TODO(butler): develop new helper function PopulateDatabaseWithRandData which calls
+// PopulateTableWithRandData on each table in the order of the fk
+// dependency graph.
+
+// PopulateTableWithRandData populates the provided table by executing exactly
+// `numInserts` statements. numRowsInserted <= numInserts because inserting into
+// an arbitrary table can fail for reasons which include:
+//  - UNIQUE or CHECK constraint violation. RandDatum is naive to these constraints.
+//  - Out of range error for a computed INT2 or INT4 column.
+//
+// If numRowsInserted == 0, PopulateTableWithRandomData or RandDatum couldn't
+// handle this table's schema. Consider increasing numInserts or filing a bug.
+func PopulateTableWithRandData(
+	rng *rand.Rand, db *gosql.DB, tableName string, numInserts int,
+) (numRowsInserted int, err error) {
+	var createStmtSQL string
+	res := db.QueryRow(fmt.Sprintf("SELECT create_statement FROM [SHOW CREATE TABLE %s]", tableName))
+	err = res.Scan(&createStmtSQL)
+	if err != nil {
+		return 0, errors.Wrapf(err, "table does not exist in db")
+	}
+	createStmt, err := parseCreateStatement(createStmtSQL)
+	if err != nil {
+		return 0, errors.Wrapf(err, "failed to determine table schema")
+	}
+
+	// Find columns subject to a foreign key constraint
+	var hasFK = map[string]bool{}
+	for _, def := range createStmt.Defs {
+		if fk, ok := def.(*tree.ForeignKeyConstraintTableDef); ok {
+			for _, col := range fk.FromCols {
+				hasFK[col.String()] = true
+			}
+		}
+	}
+
+	// Populate helper objects for insert statement creation and error out if a
+	// column's constraints will make it impossible to execute random insert
+	// statements.
+
+	colTypes := make([]*types.T, 0)
+	nullable := make([]bool, 0)
+	var colNameBuilder strings.Builder
+	comma := ""
+	for _, def := range createStmt.Defs {
+		if col, ok := def.(*tree.ColumnTableDef); ok {
+			if _, ok := hasFK[col.Name.String()]; ok {
+				// Given that this function only populates an individual table without
+				// considering other tables in the database, populating a column with a
+				// foreign key reference with actual data can be nearly impossible. To
+				// make inserts pass more frequently, this function skips populating
+				// columns with a foreign key reference. Sadly, if these columns with
+				// FKs are also NOT NULL, 0 rows will get inserted.
+
+				// TODO(butler): get the unique values from each foreign key reference and
+				// populate the column by sampling the FK's unique values.
+				if col.Nullable.Nullability == tree.Null {
+					continue
+				}
+			}
+			if col.Computed.Computed || col.Hidden {
+				// Cannot insert values into hidden or computed columns, so skip adding
+				// them to the list of columns to insert data into.
+				continue
+			}
+			colTypes = append(colTypes, tree.MustBeStaticallyKnownType(col.Type.(*types.T)))
+			nullable = append(nullable, col.Nullable.Nullability == tree.Null)
+
+			colNameBuilder.WriteString(comma)
+			colNameBuilder.WriteString(col.Name.String())
+			comma = ", "
+		}
+	}
+
+	for i := 0; i < numInserts; i++ {
+		insertVals := generateInsertStmtVals(rng, colTypes, nullable)
+		insertStmt := fmt.Sprintf("INSERT INTO %s (%s) VALUES %s;",
+			tableName,
+			colNameBuilder.String(),
+			insertVals)
+		_, err := db.Exec(insertStmt)
+		if err == nil {
+			numRowsInserted++
+		}
+	}
+	return numRowsInserted, nil
+}
+
 // GenerateRandInterestingTable takes a gosql.DB connection and creates
 // a table with all the types in randInterestingDatums and rows of the
 // interesting datums.

pkg/sql/randgen/schema_test.go

@@ -0,0 +1,76 @@
+// Copyright 2022 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package randgen
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/cockroachdb/cockroach/pkg/base"
+	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+	"github.com/cockroachdb/cockroach/pkg/testutils/serverutils"
+	"github.com/cockroachdb/cockroach/pkg/testutils/sqlutils"
+	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
+	"github.com/cockroachdb/cockroach/pkg/util/randutil"
+	"github.com/stretchr/testify/require"
+)
+
+// TestPopulateTableWithRandData generates some random tables and passes if it
+// at least one of those tables will be successfully populated.
+func TestPopulateTableWithRandData(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+
+	ctx := context.Background()
+	s, dbConn, _ := serverutils.StartServer(t, base.TestServerArgs{})
+	defer s.Stopper().Stop(ctx)
+
+	rng, _ := randutil.NewTestRand()
+
+	sqlDB := sqlutils.MakeSQLRunner(dbConn)
+	sqlDB.Exec(t, "CREATE DATABASE rand")
+
+	// Turn off auto stats collection to prevent out of memory errors on stress tests
+	sqlDB.Exec(t, "SET CLUSTER SETTING sql.stats.automatic_collection.enabled = false")
+
+	tablePrefix := "table"
+	numTables := 10
+
+	stmts := RandCreateTables(rng, tablePrefix, numTables,
+		PartialIndexMutator,
+		ForeignKeyMutator,
+	)
+
+	var sb strings.Builder
+	for _, stmt := range stmts {
+		sb.WriteString(tree.SerializeForDisplay(stmt))
+		sb.WriteString(";\n")
+	}
+	sqlDB.Exec(t, sb.String())
+
+	// To prevent the test from being flaky, pass the test if PopulateTableWithRandomData
+	// inserts at least one row in at least one table.
+	success := false
+	for i := 1; i <= numTables; i++ {
+		tableName := tablePrefix + fmt.Sprint(i)
+		numRows := 30
+		numRowsInserted, err := PopulateTableWithRandData(rng, dbConn, tableName, numRows)
+		require.NoError(t, err)
+		res := sqlDB.QueryStr(t, fmt.Sprintf("SELECT count(*) FROM %s", tableName))
+		require.Equal(t, fmt.Sprint(numRowsInserted), res[0][0])
+		if numRowsInserted > 0 {
+			success = true
+			break
+		}
+	}
+	require.Equal(t, true, success)
+}