Table output EXPLAIN seems broken border because ambiguous width

[apstndb]

The output of EXPLAIN with -t(--table) seems broken border in some environment.

$ spanner-cli -e "EXPLAIN SELECT * FROM Songs@{FORCE_INDEX=SongsBySongName}" -t
+--------------------------------------------------------------------------------------------------------+
| Query_Execution_Plan (EXPERIMENTAL)                                                                    |
+--------------------------------------------------------------------------------------------------------+
|                                                                                                        |
| .                                                                                                      |
| └── Distributed Union (subquery_cluster_node: 1)                                                    |
|     └── Distributed Cross Apply (subquery_cluster_node: 15)                                         |
|         ├── Create Batch                                                                            |
|         │   └── Distributed Union (call_type: Local, subquery_cluster_node: 4)                     |
|         │       └── Compute Struct                                                                 |
|         │           └── Scan (scan_target: SongsBySongName, scan_type: IndexScan, Full scan: true) |
|         └── Serialize Result                                                                        |
|             └── Cross Apply                                                                         |
|                 ├── Scan (scan_target: $v2, scan_type: BatchScan)                                   |
|                 └── Distributed Union (call_type: Local, subquery_cluster_node: 23)                 |
|                     └── FilterScan                                                                  |
|                         └── Scan (scan_target: Songs, scan_type: TableScan)                         |
|                                                                                                        |
+--------------------------------------------------------------------------------------------------------+

It can be fixed by replacing to unambiguous width characters.
xlab/treeprint#2 (comment)

For example

func (n *Node) Render() string {
	tree := treeprint.New()
	renderTree(tree, &Link{Dest: n})
	return "\n" + strings.NewReplacer(
		"└", "+",
		"├", "+",
		"│", "|",
		"─", "-",
		).Replace(tree.String())
}

$ spanner-cli -e "EXPLAIN SELECT * FROM Songs@{FORCE_INDEX=SongsBySongName}" -t
+----------------------------------------------------------------------------------------------------+
| Query_Execution_Plan (EXPERIMENTAL)                                                                |
+----------------------------------------------------------------------------------------------------+
|                                                                                                    |
| .                                                                                                  |
| +-- Distributed Union (subquery_cluster_node: 1)                                                   |
|     +-- Distributed Cross Apply (subquery_cluster_node: 15)                                        |
|         +-- [Input]  Create Batch                                                                  |
|         |   +-- Distributed Union (call_type: Local, subquery_cluster_node: 4)                     |
|         |       +-- Compute Struct                                                                 |
|         |           +-- Scan (Full scan: true, scan_type: IndexScan, scan_target: SongsBySongName) |
|         +-- [Map]  Serialize Result                                                                |
|             +-- Cross Apply                                                                        |
|                 +-- [Input]  Scan (scan_target: $v2, scan_type: BatchScan)                         |
|                 +-- [Map]  Distributed Union (subquery_cluster_node: 23, call_type: Local)         |
|                     +-- FilterScan                                                                 |
|                         +-- Scan (scan_type: TableScan, scan_target: Songs)                        |
|                                                                                                    |
+----------------------------------------------------------------------------------------------------+

[apstndb]

Currently, EXPLAIN with table output is not important but #57 will need correct output.

[yfuruyama]

This can't be reproduced in my terminal. What locale do you use?

This is my setting.

$ locale
LANG=""
LC_COLLATE="en_US.UTF-8"
LC_CTYPE="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

[apstndb]

It would be reproduced when LC_CTYPE="ja_JP.UTF-8"

[apstndb]

May be related
olekukonko/tablewriter#141

Added: seems to use this logic https://github.com/mattn/go-runewidth/blob/master/runewidth_posix.go#L63

[yfuruyama]

hmm... so there is no workaround other than replacing the character for the tree?

By the way, treepoint exposes EdgeType, so we can replace it with another character.
https://play.golang.org/p/w_07S6ByeEx

[apstndb]

I see, it seems changed in order to be customizable.
xlab/treeprint#4

It is possible to implement switching EdgeType value using locale related environment variables but it makes behavior unclear and I feel it doesn't much help users.
I prefer pure-ASCII characters tree format.

[yfuruyama]

+1 for using ASCII characters for tree.