Added single_intermediate_table option

[t3t5u]

Purpose

There are two modes:

• INSERT mode etc.: creates intermediate tables for each task
• REPLACE mode etc.: creates only one intermediate table

In INSERT mode etc., which creates intermediate tables for each task,
due to Embulk's mechanism, tasks are generated for each input file.
Therefore, when there are a large number of input files, a large number of intermediate tables are created.

We want INSERT mode etc. to create only one intermediate table like REPLACE mode etc. does.

[hiroyuki-sato]

Hello, @t3t5u

Thank you for proposing the new PR.

Is this PR one-shot? Or do your organization want to contribute Embulk project itself?
As you know, @dmikurube stepped down as the active maintainer. There are no active maintainer now.

We still looking for long-term maintainers around the Embulk eco-system.

As far as I know, your organization already fork embulk-output-jdbc and extend some features on your branch.
For example, Added Azure Synapse Analytics to supported products.
Will your organization maintain both plugins?

Can I ask your organization policy?

[t3t5u]

@hiroyuki-sato

Okay, I'll take a little time to reply. 🙏