[C++] Easy options to create a source node from a table

[asfimport]

Given a Table there should be a very simple way to create a source node. Something like:

  std::shared_ptr<Table> table = ...
  ARROW_RETURN_NOT_OK(arrow::compute::MakeExecNode(
      "table", plan, {}, arrow::compute::TableSourceOptions{table.get()}));

Reporter: Weston Pace / @westonpace
Assignee: Vibhatha Lakmal Abeykoon / @vibhatha

PRs and other links:

• GitHub Pull Request #12266
• GitHub Pull Request #12267

_{Note: This issue was originally created as ARROW-15258. Please see the migration documentation for further details.}

[asfimport]

Vibhatha Lakmal Abeykoon / @vibhatha:
@westonpace 

One straight forward way to provide this functionality is to use 

The ScanNodeOptions can be wrapped and create TableSourceOptions 

Reasoning: When creating from existing table, user may need to filter, select columns, etc as options. And also we can add other options required for this operation too. 

Table -> InMemoryDataset -> Scan(table, options)

Any thoughts on this. 

[asfimport]

Vibhatha Lakmal Abeykoon / @vibhatha:
I think I misinterpreted this one. Better to write a concrete interface without the scanner, but the argument could be valid. 
What sort of options should we provide?

Options: 

1. Just the table

2. Table, filter, projection, etc

3. ...

   Any thoughts on this? 

[asfimport]

Weston Pace / @westonpace:
I'd like to avoid ScanOptions entirely but I'm not opposed to using InMemoryDataset.

Filter should not be needed (this is useful when scanning only if we can push the filter down to reduce the amount of data we read from disk, otherwise a filter node is sufficient).

Projection should not be needed (this is useful when scanning only if we can push the projection down to reduce the amount of data we read from disk, e.g. which columns we want to read from disk. Otherwise a project node is sufficient).

The only parameter that probably makes sense is batch size.

If you want to use InMemoryDataset then that is one possible implementation. You can just hide the creation of ScanOptions from the user and create your own default ScanOptions with the default projection and no filter.

Otherwise you can create a record batch reader from a table and I think we have examples of how to expose a record batch reader as a generator but you would need to do your own slicing (for batch size) on top of that.

[asfimport]

Vibhatha Lakmal Abeykoon / @vibhatha:
Pleaes ignore #12266 PR. 

PR created: #12267

[asfimport]

Weston Pace / @westonpace:
Issue resolved by pull request 12267
#12267