/
resolve_tables.go
executable file
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/
resolve_tables.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package analyzer
import (
"github.com/Rock-liyi/p2pdb-store/memory"
"github.com/Rock-liyi/p2pdb-store/sql"
"github.com/Rock-liyi/p2pdb-store/sql/expression"
"github.com/Rock-liyi/p2pdb-store/sql/plan"
)
const dualTableName = "dual"
var dualTable = func() sql.Table {
t := memory.NewTable(dualTableName, sql.NewPrimaryKeySchema(sql.Schema{
{Name: "dummy", Source: dualTableName, Type: sql.LongText, Nullable: false},
}))
ctx := sql.NewEmptyContext()
// Need to run through the proper inserting steps to add data to the dummy table.
inserter := t.Inserter(ctx)
inserter.StatementBegin(ctx)
_ = inserter.Insert(sql.NewEmptyContext(), sql.NewRow("x"))
_ = inserter.StatementComplete(ctx)
_ = inserter.Close(ctx)
return t
}()
func resolveTables(ctx *sql.Context, a *Analyzer, n sql.Node, scope *Scope) (sql.Node, error) {
span, _ := ctx.Span("resolve_tables")
defer span.Finish()
return plan.TransformUp(n, func(n sql.Node) (sql.Node, error) {
if n.Resolved() {
return n, nil
}
t, ok := n.(*plan.UnresolvedTable)
if !ok {
return n, nil
}
name := t.Name()
db := t.Database
if db == "" {
db = ctx.GetCurrentDatabase()
}
if t.AsOf != nil {
// This is necessary to use functions in AS OF expressions. Because function resolution happens after table
// resolution, we resolve any functions in the AsOf here in order to evaluate them immediately. A better solution
// might be to defer evaluating the expression until later in the analysis, but that requires bigger changes.
asOfExpr, err := expression.TransformUp(t.AsOf, resolveFunctionsInExpr(ctx, a))
if err != nil {
return nil, err
}
if !asOfExpr.Resolved() {
return nil, sql.ErrInvalidAsOfExpression.New(asOfExpr.String())
}
asOf, err := asOfExpr.Eval(ctx, nil)
if err != nil {
return nil, err
}
rt, database, err := a.Catalog.TableAsOf(ctx, db, name, asOf)
if err != nil {
return handleTableLookupFailure(err, name, db, a, t)
}
a.Log("table resolved: %q as of %s", rt.Name(), asOf)
return plan.NewResolvedTable(rt, database, asOf), nil
}
rt, database, err := a.Catalog.Table(ctx, db, name)
if err != nil {
return handleTableLookupFailure(err, name, db, a, t)
}
a.Log("table resolved: %s", t.Name())
return plan.NewResolvedTable(rt, database, nil), nil
})
}
func handleTableLookupFailure(err error, tableName string, dbName string, a *Analyzer, t *plan.UnresolvedTable) (sql.Node, error) {
if sql.ErrDatabaseNotFound.Is(err) {
if tableName == dualTableName {
a.Log("table resolved: %q", t.Name())
return plan.NewResolvedTable(dualTable, nil, nil), nil
}
if dbName == "" {
return nil, sql.ErrNoDatabaseSelected.New()
}
} else if sql.ErrTableNotFound.Is(err) {
if tableName == dualTableName {
a.Log("table resolved: %s", t.Name())
return plan.NewResolvedTable(dualTable, nil, nil), nil
}
}
return nil, err
}