Support Partitioned DML with statement hints

[apstndb]

DMLs can be prefixed by statement hints.

https://cloud.google.com/spanner/docs/reference/standard-sql/dml-syntax#delete-statement

[statement_hint_expr] UPDATE table_name [table_hint_expr] [[AS] alias]

https://cloud.google.com/spanner/docs/reference/standard-sql/dml-syntax#update-statement

[statement_hint_expr] UPDATE table_name [table_hint_expr] [[AS] alias]

It seems that only permitted statement hint is PDML_MAX_PARALLELISM for Partitioned DML, so only we need is relaxing pattern of pdmlRe.

spanner-cli/statement.go

Line 105 in e44e60f

pdmlRe = regexp.MustCompile(`(?is)^PARTITIONED\s+((?:INSERT|UPDATE|DELETE)\s+.+$)`)

[yfuruyama]

Thank you for catching this.

PARTITIONED statement is a spanner-cli specific statement, so it's a little bit tricky to decide where the statement hint should be placed.

1. @{hint} PARTITIONED UPDATE ...
2. PARTITIONED @{hint} UPDATE ...

It's possible that other prefixes will be supported in front of DML syntax, so I think option 2 might be better. Then we can think of the PARTITIONED statement syntax as PARTITIONED [DML statement].