Fix type coercion in cascading non-literal updates (vitessio#14524)

Signed-off-by: Manan Gupta <manan@planetscale.com>

go/test/endtoend/vtgate/foreignkey/fk_test.go

@@ -880,6 +880,13 @@ func TestFkQueries(t *testing.T) {
  "insert into fk_multicol_t16 (id, cola, colb) values (1,1,1),(2,2,2)",
  "update fk_multicol_t15 set cola = 3, colb = (id * 2) - 2",
  },
+ }, {
+ name: "Update that sets to 0 and -0 values",
+ queries: []string{
+ "insert into fk_t15 (id, col) values (1,'-0'), (2, '0'), (3, '5'), (4, '-5')",
+ "insert into fk_t16 (id, col) values (1,'-0'), (2, '0'), (3, '5'), (4, '-5')",
+ "update fk_t15 set col = col * (col - (col))",
+ },
  },
  }
 

go/vt/vtgate/engine/fk_cascade.go

@@ -25,6 +25,7 @@ import (
  querypb "vitess.io/vitess/go/vt/proto/query"
  vtrpcpb "vitess.io/vitess/go/vt/proto/vtrpc"
  "vitess.io/vitess/go/vt/vterrors"
+ "vitess.io/vitess/go/vt/vtgate/evalengine"
 )
 
 // FkChild contains the Child Primitive to be executed collecting the values from the Selection Primitive using the column indexes.
@@ -40,14 +41,16 @@ type FkChild struct {
 }
 
 // NonLiteralUpdateInfo stores the information required to process non-literal update queries.
-// It stores 3 information-
-// 1. UpdateExprCol- The index of the updated expression in the select query.
-// 2. UpdateExprBvName- The bind variable name to store the updated expression into.
-// 3. CompExprCol- The index of the comparison expression in the select query to know if the row value is actually being changed or not.
+// It stores 4 information-
+// 1. ExprCol- The index of the column being updated in the select query.
+// 2. CompExprCol- The index of the comparison expression in the select query to know if the row value is actually being changed or not.
+// 3. UpdateExprCol- The index of the updated expression in the select query.
+// 4. UpdateExprBvName- The bind variable name to store the updated expression into.
 type NonLiteralUpdateInfo struct {
+ ExprCol int
+ CompExprCol int
  UpdateExprCol int
  UpdateExprBvName string
- CompExprCol int
 }
 
 // FkCascade is a primitive that implements foreign key cascading using Selection as values required to execute the FkChild Primitives.
@@ -185,7 +188,19 @@ func (fkc *FkCascade) executeNonLiteralExprFkChild(ctx context.Context, vcursor
 
  // Next, we need to copy the updated expressions value into the bind variables map.
  for _, info := range child.NonLiteralInfo {
- bindVars[info.UpdateExprBvName] = sqltypes.ValueBindVariable(row[info.UpdateExprCol])
+ // Type case the value to that of the column that we are updating.
+ // This is required for example when we receive an updated float value of -0, but
+ // the column being updated is a varchar column, then if we don't coerce the value of -0 to
+ // varchar, MySQL ends up setting it to '0' instead of '-0'.
+ finalVal := row[info.UpdateExprCol]
+ if !finalVal.IsNull() {
+ var err error
+ finalVal, err = evalengine.CoerceTo(finalVal, selectionRes.Fields[info.ExprCol].Type)
+ if err != nil {
+ return err
+ }
+ }
+ bindVars[info.UpdateExprBvName] = sqltypes.ValueBindVariable(finalVal)
  }
  _, err := vcursor.ExecutePrimitive(ctx, child.Exec, bindVars, wantfields)
  if err != nil {

go/vt/vtgate/planbuilder/operators/update.go

@@ -334,6 +334,7 @@ func addNonLiteralUpdExprToSelect(ctx *plancontext.PlanningContext, updExpr *sql
  info := engine.NonLiteralUpdateInfo{
  CompExprCol: -1,
  UpdateExprCol: -1,
+ ExprCol: -1,
  }
  // Add the expressions to the select expressions. We make sure to reuse the offset if it has already been added once.
  for idx, selectExpr := range exprs {
@@ -343,6 +344,9 @@ func addNonLiteralUpdExprToSelect(ctx *plancontext.PlanningContext, updExpr *sql
  if ctx.SemTable.EqualsExpr(selectExpr.(*sqlparser.AliasedExpr).Expr, updExpr.Expr) {
  info.UpdateExprCol = idx
  }
+ if ctx.SemTable.EqualsExpr(selectExpr.(*sqlparser.AliasedExpr).Expr, updExpr.Name) {
+ info.ExprCol = idx
+ }
  }
  // If the expression doesn't exist, then we add the expression and store the offset.
  if info.CompExprCol == -1 {
@@ -353,6 +357,10 @@ func addNonLiteralUpdExprToSelect(ctx *plancontext.PlanningContext, updExpr *sql
  info.UpdateExprCol = len(exprs)
  exprs = append(exprs, aeWrap(updExpr.Expr))
  }
+ if info.ExprCol == -1 {
+ info.ExprCol = len(exprs)
+ exprs = append(exprs, aeWrap(updExpr.Name))
+ }
  return info, exprs
 }
 

go/vt/vtgate/planbuilder/testdata/foreignkey_cases.json

@@ -840,9 +840,10 @@
  ],
  "NonLiteralUpdateInfo": [
  {
+ "ExprCol": 0,
+ "CompExprCol": 1,
  "UpdateExprCol": 2,
- "UpdateExprBvName": "fkc_upd",
- "CompExprCol": 1
+ "UpdateExprBvName": "fkc_upd"
  }
  ],
  "Query": "update u_tbl3 set col3 = null where (col3) in ::fkc_vals and (:fkc_upd is null or (u_tbl3.col3) not in ((:fkc_upd)))",
@@ -901,9 +902,10 @@
  ],
  "NonLiteralUpdateInfo": [
  {
+ "ExprCol": 0,
+ "CompExprCol": 1,
  "UpdateExprCol": 2,
- "UpdateExprBvName": "fkc_upd",
- "CompExprCol": 1
+ "UpdateExprBvName": "fkc_upd"
  }
  ],
  "Inputs": [
@@ -958,9 +960,10 @@
  ],
  "NonLiteralUpdateInfo": [
  {
+ "ExprCol": 0,
+ "CompExprCol": 1,
  "UpdateExprCol": 2,
- "UpdateExprBvName": "fkc_upd1",
- "CompExprCol": 1
+ "UpdateExprBvName": "fkc_upd1"
  }
  ],
  "Inputs": [
@@ -2102,9 +2105,10 @@
  ],
  "NonLiteralUpdateInfo": [
  {
+ "ExprCol": 0,
+ "CompExprCol": 1,
  "UpdateExprCol": 2,
- "UpdateExprBvName": "fkc_upd",
- "CompExprCol": 1
+ "UpdateExprBvName": "fkc_upd"
  }
  ],
  "Inputs": [
@@ -2199,9 +2203,10 @@
  ],
  "NonLiteralUpdateInfo": [
  {
+ "ExprCol": 0,
+ "CompExprCol": 2,
  "UpdateExprCol": 3,
- "UpdateExprBvName": "fkc_upd",
- "CompExprCol": 2
+ "UpdateExprBvName": "fkc_upd"
  }
  ],
  "Inputs": [
@@ -2327,14 +2332,16 @@
  ],
  "NonLiteralUpdateInfo": [
  {
+ "ExprCol": 0,
+ "CompExprCol": 2,
  "UpdateExprCol": 3,
- "UpdateExprBvName": "fkc_upd",
- "CompExprCol": 2
+ "UpdateExprBvName": "fkc_upd"
  },
  {
+ "ExprCol": 1,
+ "CompExprCol": 4,
  "UpdateExprCol": 5,
- "UpdateExprBvName": "fkc_upd1",
- "CompExprCol": 4
+ "UpdateExprBvName": "fkc_upd1"
  }
  ],
  "Query": "update /*+ SET_VAR(foreign_key_checks=OFF) */ u_multicol_tbl3 set cola = :fkc_upd, colb = :fkc_upd1 where (cola, colb) in ::fkc_vals",