sql/randgen: make insert values deterministic with a seed

Previously, when randgen built values for an INSERT statement it used
the rand library. This PR uses the passed in rand.Rand created from the
test seed so that test failures can be reproduced deterministically
using COCKROACH_RANDOM_SEED.

Epic: None
Informs: #109431

Release note: None

pkg/sql/randgen/schema.go

@@ -289,14 +289,14 @@ func generateInsertStmtVals(rng *rand.Rand, colTypes []*types.T, nullable []bool
 	for j := 0; j < len(colTypes); j++ {
 		valBuilder.WriteString(comma)
 		var d tree.Datum
-		if rand.Intn(10) < 4 {
+		if rng.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(oid.Oid(rand.Intn(len(types.OidToType))))
+			d = tree.NewDOid(oid.Oid(rng.Intn(len(types.OidToType))))
 		}
 		if d == nil {
 			d = RandDatum(rng, colTypes[j], nullable[j])
@@ -462,26 +462,26 @@ func GenerateRandInterestingTable(db *gosql.DB, dbName, tableName string) error
 
 // randColumnTableDef produces a random ColumnTableDef for a non-computed
 // column, with a random type and nullability.
-func randColumnTableDef(rand *rand.Rand, tableIdx int, colIdx int) *tree.ColumnTableDef {
-	g := randident.NewNameGenerator(&nameGenCfg, rand, fmt.Sprintf("col%d_", tableIdx))
+func randColumnTableDef(rng *rand.Rand, tableIdx int, colIdx int) *tree.ColumnTableDef {
+	g := randident.NewNameGenerator(&nameGenCfg, rng, fmt.Sprintf("col%d_", tableIdx))
 	colName := g.GenerateOne(colIdx)
 	columnDef := &tree.ColumnTableDef{
 		// We make a unique name for all columns by prefixing them with the table
 		// index to make it easier to reference columns from different tables.
 		Name: tree.Name(colName),
-		Type: RandColumnType(rand),
+		Type: RandColumnType(rng),
 	}
 	// Slightly prefer non-nullable columns
 	if columnDef.Type.(*types.T).Family() == types.OidFamily {
 		// Make all OIDs nullable so they're not part of a PK or unique index.
 		// Some OID types have a very narrow range of values they accept, which
 		// may cause many duplicate row errors.
-		columnDef.Nullable.Nullability = tree.RandomNullability(rand, true /* nullableOnly */)
-	} else if rand.Intn(2) == 0 {
+		columnDef.Nullable.Nullability = tree.RandomNullability(rng, true /* nullableOnly */)
+	} else if rng.Intn(2) == 0 {
 		// Slightly prefer non-nullable columns
 		columnDef.Nullable.Nullability = tree.NotNull
 	} else {
-		columnDef.Nullable.Nullability = tree.RandomNullability(rand, false /* nullableOnly */)
+		columnDef.Nullable.Nullability = tree.RandomNullability(rng, false /* nullableOnly */)
 	}
 	return columnDef
 }