ddl: fill in original default for extra writable columns in batch insert (#40198)

[ti-chi-bot]

This is an automated cherry-pick of #40198

Signed-off-by: YangKeao yangkeao@chunibyo.icu

What problem does this PR solve?

Issue Number: close #40192, close #50993

Problem Summary:

When a column is in write-only state, the INSERT ignore statement without specifying columns doesn't fill in the origin default value. INSERT actually works, because it appends, see

tidb/table/tables/tables.go

Lines 798 to 813 in 95f0dc5

	if col.State != model.StatePublic &&
	// Update call `AddRecord` will already handle the write only column default value.
	// Only insert should add default value for write only column.
	!opt.IsUpdate {
	// If col is in write only or write reorganization state, we must add it with its default value.
	value, err = table.GetColOriginDefaultValue(sctx, col.ToInfo())
	if err != nil {
	return nil, err
	}
	// add value to `r` for dirty db in transaction.
	// Otherwise when update will panic cause by get value of column in write only state from dirty db.
	if col.Offset < len(r) {
	r[col.Offset] = value
	} else {
	r = append(r, value)
	}

This case can also work well with unique index (if the origin default value is NULL) and NOT NULL.

It also avoids inserting more than 1 rows if the columns is NOT NULL and write-only (as the user cannot set a value for it). I doubt whether it is expected. (However, many other places depend on this behavior, and as I've tried, modifying this behavior is really scarying... I didn't touch it in this PR).

What is changed and how it works?

Append the origin default value if there are extra write-only column.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Release note

Fix the issue that batch inserting data while dropping column could cause panic.

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-05-07 05:57:00.563269505 +0000 UTC m=+941574.320405073: ☑️ agreed by Defined2014.
• 2024-05-07 05:58:11.181668099 +0000 UTC m=+941644.938803672: ☑️ agreed by hawkingrei.

[xhebox]

/test build

[ti-chi-bot]

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This pull-request has been approved by: Defined2014

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[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 6 lines in your changes are missing coverage. Please review.

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Additional details and impacted files

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