Unclear what chunksize represents in to_sql() docs
From http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.to_sql.html

> **chunksize** _: int, default None_
> If not None, then rows will be written in batches of this size at a time. If None, all rows will be written at once.

"this size"? Sounds like it could be the max size in bytes. How about "this number of rows"?

I think that's right given read_sql() says:
http://pandas.pydata.org/pandas-docs/stable/generated/pandas.read_sql.html

> **chunksize** _: int, default None_
> If specified, return an iterator where chunksize is the number of rows to include in each chunk.

If that's not right please let me know. Thanks!
