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Add support for Mysql row_count() function #6179

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Merged
systay merged 5 commits into from
May 14, 2020
Merged

Add support for Mysql row_count() function #6179

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481adff
Added row_count to vtgate session
harshit-gangal May 13, 2020
3ef15e2
added row_count in expression rewritting
harshit-gangal May 13, 2020
2de37ae
added row_count endtoend test
harshit-gangal May 13, 2020
830f31d
update row_count as per mysql spec
harshit-gangal May 13, 2020
dcb74ae
Turned test into table driven
systay May 14, 2020
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162 changes: 85 additions & 77 deletions go/vt/proto/vtgate/vtgate.pb.go
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73 changes: 47 additions & 26 deletions go/vt/sqlparser/expression_rewriting.go
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ type BindVarNeeds struct {
NeedLastInsertID bool
NeedDatabase bool
NeedFoundRows bool
NeedRowCount bool
NeedUserDefinedVariables bool
}

Expand Down Expand Up @@ -64,6 +65,9 @@ func RewriteAST(in Statement) (*RewriteASTResult, error) {
if _, ok := er.bindVars[FoundRowsName]; ok {
r.NeedFoundRows = true
}
if _, ok := er.bindVars[RowCountName]; ok {
r.NeedRowCount = true
}
if _, ok := er.bindVars[UserDefinedVariableName]; ok {
r.NeedUserDefinedVariables = true
}
Expand Down Expand Up @@ -116,6 +120,9 @@ const (
//FoundRowsName is a reserved bind var name for found_rows()
FoundRowsName = "__vtfrows"

//RowCountName is a reserved bind var name for row_count()
RowCountName = "__vtrcount"

//UserDefinedVariableName is what we prepend bind var names for user defined variables
UserDefinedVariableName = "__vtudv"
)
Expand Down Expand Up @@ -145,32 +152,7 @@ func (er *expressionRewriter) goingDown(cursor *Cursor) bool {
return false
}
case *FuncExpr:
switch {
// last_insert_id() -> :__lastInsertId
case node.Name.EqualString("last_insert_id"):
if len(node.Exprs) > 0 { //last_insert_id(x)
er.err = vterrors.New(vtrpc.Code_UNIMPLEMENTED, "Argument to LAST_INSERT_ID() not supported")
} else {
cursor.Replace(bindVarExpression(LastInsertIDName))
er.needBindVarFor(LastInsertIDName)
}
case er.shouldRewriteDatabaseFunc &&
(node.Name.EqualString("database") ||
node.Name.EqualString("schema")):
if len(node.Exprs) > 0 {
er.err = vterrors.Errorf(vtrpc.Code_INVALID_ARGUMENT, "Syntax error. %s() takes no arguments", node.Name.String())
} else {
cursor.Replace(bindVarExpression(DBVarName))
er.needBindVarFor(DBVarName)
}
case node.Name.EqualString("found_rows"):
if len(node.Exprs) > 0 {
er.err = vterrors.New(vtrpc.Code_INVALID_ARGUMENT, "Arguments to FOUND_ROWS() not supported")
} else {
cursor.Replace(bindVarExpression(FoundRowsName))
er.needBindVarFor(FoundRowsName)
}
}
er.funcRewrite(cursor, node)
case *ColName:
if node.Name.at == SingleAt {
cursor.Replace(bindVarExpression(UserDefinedVariableName + node.Name.CompliantName()))
Expand All @@ -180,6 +162,45 @@ func (er *expressionRewriter) goingDown(cursor *Cursor) bool {
return true
}

func (er *expressionRewriter) funcRewrite(cursor *Cursor, node *FuncExpr) {
switch {
// last_insert_id() -> :__lastInsertId
case node.Name.EqualString("last_insert_id"):
if len(node.Exprs) > 0 { //last_insert_id(x)
er.err = vterrors.New(vtrpc.Code_UNIMPLEMENTED, "Argument to LAST_INSERT_ID() not supported")
} else {
cursor.Replace(bindVarExpression(LastInsertIDName))
er.needBindVarFor(LastInsertIDName)
}
// database() -> :__vtdbname
case er.shouldRewriteDatabaseFunc &&
(node.Name.EqualString("database") ||
node.Name.EqualString("schema")):
if len(node.Exprs) > 0 {
er.err = vterrors.Errorf(vtrpc.Code_INVALID_ARGUMENT, "Syntax error. %s() takes no arguments", node.Name.String())
} else {
cursor.Replace(bindVarExpression(DBVarName))
er.needBindVarFor(DBVarName)
}
// found_rows() -> :__vtfrows
case node.Name.EqualString("found_rows"):
if len(node.Exprs) > 0 {
er.err = vterrors.New(vtrpc.Code_INVALID_ARGUMENT, "Arguments to FOUND_ROWS() not supported")
} else {
cursor.Replace(bindVarExpression(FoundRowsName))
er.needBindVarFor(FoundRowsName)
}
// row_count() -> :__vtrcount
case node.Name.EqualString("row_count"):
if len(node.Exprs) > 0 {
er.err = vterrors.New(vtrpc.Code_INVALID_ARGUMENT, "Arguments to ROW_COUNT() not supported")
} else {
cursor.Replace(bindVarExpression(RowCountName))
er.needBindVarFor(RowCountName)
}
}
}

// instead of creating new objects, we'll reuse this one
var token = struct{}{}

Expand Down
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