Add show table $table_name next_row_id syntax

[crazycs520]

Feature Request

Add show table $table_name next_row_id to get the next global table row id.

Is your feature request related to a problem? Please describe:

Currently, TiDB has admin show $table_name next_row_id to get the next global table row id.

But admin show syntax needs the super privilege. Getting the next_row_id no need to use super privilege, only use SELECT privilege will be ok. We can add show $table_name next_row_id syntax to get next_row_id.

Describe the feature you'd like:

test> show table test.t next_row_id;
+---------+------------+-------------+--------------------+
| DB_NAME | TABLE_NAME | COLUMN_NAME | NEXT_GLOBAL_ROW_ID |
+---------+------------+-------------+--------------------+
| test    | t          | _tidb_rowid | 30001              |
+---------+------------+-------------+--------------------+

Teachability, Documentation, Adoption, Migration Strategy:

For compatibility, we can't remove admin show $table_name next_row_id soon.

[zhang555]

I want solve this issue , but I have a problem .

For add show $table_name next_row_id syntax , I edit parser.y file .

before my edit :

ShowStmt:
	"SHOW" ShowTargetFilterable ShowLikeOrWhereOpt
	{
		stmt := $2.(*ast.ShowStmt)
		if $3 != nil {
			if x, ok := $3.(*ast.PatternLikeExpr); ok && x.Expr == nil {
				stmt.Pattern = x
			} else {
				stmt.Where = $3.(ast.ExprNode)
			}
		}
		$$ = stmt
	}
|	"SHOW" "CREATE" "TABLE" TableName
	{
		$$ = &ast.ShowStmt{
			Tp:    ast.ShowCreateTable,
			Table: $4.(*ast.TableName),
		}
	}

after my edit :

ShowStmt:
	"SHOW" ShowTargetFilterable ShowLikeOrWhereOpt
	{
		stmt := $2.(*ast.ShowStmt)
		if $3 != nil {
			if x, ok := $3.(*ast.PatternLikeExpr); ok && x.Expr == nil {
				stmt.Pattern = x
			} else {
				stmt.Where = $3.(ast.ExprNode)
			}
		}
		$$ = stmt
	}
|	"SHOW" TableName "NEXT_ROW_ID"
	{
		$$ = &ast.ShowStmt{
			Tp:     ast.ShowTableNextRowId,
			Tables: []*ast.TableName{$2.(*ast.TableName)},
		}
	}
|	"SHOW" "CREATE" "TABLE" TableName
	{
		$$ = &ast.ShowStmt{
			Tp:    ast.ShowCreateTable,
			Table: $4.(*ast.TableName),
		}
	}

but when I make it , I get a error :

gofmt (simplify)
bin/goyacc -o parser.go -p yy -t Parser parser.y
conflicts: 1 reduce/reduce
conflicts: 7 shift/reduce
Please check y.output for more information
make: *** [parser.go] Error 1

what went wrong with parser.y file ?

[crazycs520]

@zhang555 ， Thanks for your contribution.
After consideration, since SHOW syntax has many syntaxes,
SHOW TALBLE $table_name NEXT_ROW_ID maybe a better syntax.