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schemadiff: reject non-deterministic function in new column's default value #16684

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merged 4 commits into from
Sep 2, 2024
Merged

schemadiff: reject non-deterministic function in new column's default value #16684

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6133fbc
schemadiff: new NonDeterministicDefaultStrategy, can reject non-deter…
shlomi-noach Aug 29, 2024
d588cd8
recursion is not needed
shlomi-noach Sep 2, 2024
88895d7
formatting directive
shlomi-noach Sep 2, 2024
2cd96bc
Removing NonDeterministicDefaultStrategy. It is non-optional as MySQL…
shlomi-noach Sep 2, 2024
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10 changes: 10 additions & 0 deletions go/vt/schemadiff/errors.go
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Original file line number Diff line number Diff line change
Expand Up @@ -487,3 +487,13 @@ type PartitionSpecNonExclusiveError struct {
func (e *PartitionSpecNonExclusiveError) Error() string {
return fmt.Sprintf("ALTER TABLE on %s, may only have a single partition spec change, and other changes are not allowed. Found spec: %s; and change: %s", sqlescape.EscapeID(e.Table), sqlparser.CanonicalString(e.PartitionSpec), e.ConflictingStatement)
}

type NonDeterministicDefaultError struct {
Table string
Column string
Function string
}

func (e *NonDeterministicDefaultError) Error() string {
return fmt.Sprintf("column %s.%s default value uses non-deterministic function: %s", sqlescape.EscapeID(e.Table), sqlescape.EscapeID(e.Column), e.Function)
}
37 changes: 37 additions & 0 deletions go/vt/schemadiff/table.go
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Expand Up @@ -1731,6 +1731,33 @@ func evaluateColumnReordering(t1SharedColumns, t2SharedColumns []*sqlparser.Colu
return minimalColumnReordering
}

// This function looks for a non-deterministic function call in the given expression.
// If recurses into all function arguments.
// The known non-deterministic function we handle are:
// - UUID()
// - RAND()
// - SYSDATE()
func findNoNondeterministicFunction(expr sqlparser.Expr) (foundFunction string) {
_ = sqlparser.Walk(func(node sqlparser.SQLNode) (kontinue bool, err error) {
switch node := node.(type) {
case *sqlparser.CurTimeFuncExpr:
switch node.Name.Lowered() {
case "sysdate":
foundFunction = node.Name.String()
return false, nil
}
case *sqlparser.FuncExpr:
switch node.Name.Lowered() {
case "uuid", "rand":
foundFunction = node.Name.String()
return false, nil
}
}
return true, nil
}, expr)
return foundFunction
}

// Diff compares this table statement with another table statement, and sees what it takes to
// change this table to look like the other table.
// It returns an AlterTable statement if changes are found, or nil if not.
Expand Down Expand Up @@ -1852,6 +1879,16 @@ func (c *CreateTableEntity) diffColumns(alterTable *sqlparser.AlterTable,
addColumn := &sqlparser.AddColumns{
Columns: []*sqlparser.ColumnDefinition{t2Col},
}
// See whether this ADD COLUMN has a non-deterministic default value
if t2Col.Type.Options.Default != nil && !t2Col.Type.Options.DefaultLiteral {
if function := findNoNondeterministicFunction(t2Col.Type.Options.Default); function != "" {
return &NonDeterministicDefaultError{
Table: c.Name(),
Column: t2Col.Name.String(),
Function: function,
}
}
}
if t2ColIndex < expectAppendIndex {
// This column is added somewhere in between existing columns, not appended at end of column list
if t2ColIndex == 0 {
Expand Down
84 changes: 74 additions & 10 deletions go/vt/schemadiff/table_test.go
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Expand Up @@ -28,16 +28,17 @@ import (

func TestCreateTableDiff(t *testing.T) {
tt := []struct {
name string
from string
to string
fromName string
toName string
diff string
diffs []string
cdiff string
cdiffs []string
errorMsg string
name string
from string
to string
fromName string
toName string
diff string
diffs []string
cdiff string
cdiffs []string
errorMsg string
// hints:
autoinc int
rotation int
fulltext int
Expand All @@ -47,6 +48,7 @@ func TestCreateTableDiff(t *testing.T) {
algorithm int
enumreorder int
subsequent int
//
textdiffs []string
atomicdiffs []string
}{
Expand Down Expand Up @@ -449,6 +451,68 @@ func TestCreateTableDiff(t *testing.T) {
"+ `y` int,",
},
},
{
name: "added column with non deterministic expression, uuid, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (uuid()))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "uuid"}).Error(),
},
{
name: "added column with non deterministic expression, UUID, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (UUID()))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "UUID"}).Error(),
},
{
name: "added column with non deterministic expression, uuid, spacing, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (uuid ()))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "uuid"}).Error(),
},
{
name: "added column with non deterministic expression, uuid, inner, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (left(uuid(),10)))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "uuid"}).Error(),
},
{
name: "added column with non deterministic expression, rand, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (2.0 + rand()))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "rand"}).Error(),
},
{
name: "added column with non deterministic expression, sysdate, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (sysdate()))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "sysdate"}).Error(),
},
{
name: "added column with non deterministic expression, sysdate, reject",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (to_days(sysdate())))",
errorMsg: (&NonDeterministicDefaultError{Table: "t1", Column: "v", Function: "sysdate"}).Error(),
},
{
name: "added column with deterministic expression, now, reject does not apply",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (now()))",
diff: "alter table t1 add column v varchar(36) not null default (now())",
cdiff: "ALTER TABLE `t1` ADD COLUMN `v` varchar(36) NOT NULL DEFAULT (now())",
textdiffs: []string{
"+ `v` varchar(36) NOT NULL DEFAULT (now()),",
},
},
{
name: "added column with deterministic expression, curdate, reject does not apply",
from: "create table t1 (id int primary key, a int)",
to: "create table t2 (id int primary key, a int, v varchar(36) not null default (to_days(curdate())))",
diff: "alter table t1 add column v varchar(36) not null default (to_days(curdate()))",
cdiff: "ALTER TABLE `t1` ADD COLUMN `v` varchar(36) NOT NULL DEFAULT (to_days(curdate()))",
textdiffs: []string{
"+ `v` varchar(36) NOT NULL DEFAULT (to_days(curdate())),",
},
},
// enum
{
name: "expand enum",
Expand Down
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