MDEV-37009 bulk insert into vector index

[shabbann]

Add support for bulk insertion into MHNSW vector indexes during ALTER TABLE

[gemini-code-assist]

Code Review

This pull request introduces bulk insert support for hierarchical navigable small world (mhnsw) indexes during table copy operations. The reviewer identified several critical issues, including compilation errors from accessing bulk_insert_active through the wrong pointer, an uninitialized member variable, and an ignored return value during bulk insert initialization. Suggestions were also made to reset the active flag on failure and correct formatting to match the repository's style.

[gemini-code-assist]

The member bulk_insert_active was added to the TABLE struct in sql/table.h, but here it is accessed via hlindex->bulk_insert_active. Since hlindex is not of type TABLE*, this will cause a compilation error. It should be accessed directly as bulk_insert_active (or this->bulk_insert_active).

Additionally, please update the indentation to 2 spaces to match the repository's implicit style guide.

  DBUG_ASSERT(s->hlindexes() == (hlindex != NULL));
  if (hlindex && hlindex->in_use)
  {
    if (bulk_insert_active)
      return mhnsw_bulk_insert_row(this, key_info + s->keys);
    else
      return mhnsw_insert(this, key_info + s->keys);
  }
  return 0;

[gemini-code-assist]

There are three issues here:

1. bulk_insert_active is a member of TABLE, not hlindex, so accessing it via hlindex->bulk_insert_active will cause a compilation error.
2. If mhnsw_bulk_insert_begin fails (returns a non-zero error code), bulk_insert_active should be reset to false so that subsequent inserts do not incorrectly attempt bulk insertion.
3. The indentation should be updated to 2 spaces to match the repository's implicit style guide.

int TABLE::hlindexes_bulk_insert_begin(ha_rows rows)
{
  if (hlindex && hlindex->in_use)
  {
    bulk_insert_active= true;
    int err= mhnsw_bulk_insert_begin(this, key_info + s->keys, rows);
    if (err)
      bulk_insert_active= false;
    return err;
  }
  return 0;
}

int TABLE::hlindexes_bulk_insert_end()
{
  if (hlindex && hlindex->in_use)
  {
    bulk_insert_active= false;
    return mhnsw_bulk_insert_end(this, key_info + s->keys);
  }
  return 0;
}

[gemini-code-assist]

The return value of to->hlindexes_bulk_insert_begin is currently ignored. If the bulk insert initialization fails, we should handle the error, print it, and avoid setting hlindex_bulk_started to 1 so that we do not proceed with the bulk insert or attempt to end it later.

Additionally, please update the indentation to 2 spaces to match the repository's implicit style guide.

  if (!to->s->long_unique_table)
  {
    to->file->ha_start_bulk_insert(from->file->stats.records,
                                   ignore ? 0 : HA_CREATE_UNIQUE_INDEX_BY_SORT);
    bulk_insert_started= 1;

    if (to->s->hlindexes())
    {
      if ((error= to->hlindexes_bulk_insert_begin(from->file->stats.records)))
      {
        to->file->print_error(error, MYF(0));
      }
      else
      {
        hlindex_bulk_started= 1;
      }
    }
  }

[gemini-code-assist]

Please update the indentation to 2 spaces and add proper spacing around operators (e.g., hlindex_bulk_started = 0;) to match the repository's implicit style guide.

  if (hlindex_bulk_started && to->hlindexes_bulk_insert_end() && error <= 0)
  {
    if (!thd->is_error())
      to->file->print_error(my_errno, MYF(0));
    error= 1;
  }
  hlindex_bulk_started= 0;

[gemini-code-assist]

The new member variable bulk_insert_active is not initialized. To prevent potential uninitialized memory bugs, it is highly recommended to initialize it to false directly in the struct definition using C++ member initialization.

  bool bulk_insert_active= false;    /* mhnsw bulk_insert_started flag */