solr = pysolr.Solr('http://***', timeout=10, auth=('username','password'))
cursor = '*'
df1 = pd.DataFrame()

# Batch computation
# Fetch 100 rows per 10 times: 10 * 100 --> using nextCursorMark
for x in range(0,10):     
    results = solr.search('var_1:* AND var_2":true AND var_year:2020', **{
        'fl': 'id,var_3,var_4',
        'cursorMark': cursor,
        'sort': 'id desc',
        'rows': '100',
        'wt':'csv'
    })
    cursor = results.nextCursorMark
    df1 = df1.append(results.docs, ignore_index=True)