我使用xlsxwriter python包将数据从PostgreSQL数据库导出到django项目中的excel。我已经实现了一个Django命令来执行此操作，但问题是存在超过4百万条数据记录并且写入该文件会占用我的所有RAM，并且该进程会被终止。
日志：
[export_user_data_to_excel]> Generating excel file with:
3913616 Instagram publications
1250156 Instagram hashtags
513124 Twitter publications
127912 Twitter hashtags
Killed
我尝试过一个名为＆＃39; constant_memory＆＃39;的参数。但它似乎并没有什么不同。以下是编写excel文件的方法：
def write_to_excel_perf(filename, instagram_publications, instagram_tags, twitter_publications, twitter_tags, instance):
"""
Export the current queryset to an excel file in xlsx format.
Optimized for low memory consumption and better performance
http://xlsxwriter.readthedocs.io/working_with_memory.html#memory-perf
"""
logger.info("[write_to_excel_perf]> Openning Workbook..")
book = xlsxwriter.Workbook(filename, {'constant_memory': True})
if 'instagram' in instance:
logger.info("[write_to_excel_perf]> Writting Instagram publications..")
sheet = book.add_worksheet('Instagram Media')
# Adding media page
titles = ["Type", "City", "Date", "Instagram Id", "Instagram URL", "caption", "likes",
"author", "location id", "location name", "lat", "lng"]
i = 0
for title in titles:
sheet.write(0, i, title)
i += 1
row_index = 1
# We improve the performance making sure that we query by related data using select_related
# and prefetch_related when needed
instagram_publications = instagram_publications.select_related('location__spot__city', 'author', 'location')
for el in instagram_publications:
# ["Type", "Date", "Instagram Id", "Instagram URL", "caption", "likes", "author", "author_profile",
# "location id", "location name", "lat", "lng"]
mediaType = 'Photo' if el.mediaType == '1' else 'Video'
city = el.location.spot.city.name if el.location is not None and el.location.spot.city is not None else "Undefined"
publication_date = el.publication_date.strftime("%d/%m/%Y %H:%M")
username = el.author.username if el.author is not None else "Undefined"
location_id = el.location.instagramID if el.location is not None else "Undefined"
location_name = el.location.name if el.location is not None else "Undefined"
location_lat = el.location.position.y if el.location is not None else "Undefined"
location_lng = el.location.position.x if el.location is not None else "Undefined"
row = [mediaType, city, publication_date, el.instagramID, el.instagram_url, el.caption, el.likes,
username, location_id, location_name, location_lat,
location_lng]
column_index = 0
for value in row:
sheet.write(row_index, column_index, value)
column_index += 1
row_index += 1
# Adding tag page
sheet = book.add_worksheet('Instagram Tags')
titles = ["Hashtag", "Quantity"]
i = 0
for title in titles:
sheet.write(0, i, title)
i += 1
row_index = 1
if instagram_tags is not None:
logger.info("[write_to_excel_perf]> Writting Instagram hashtags..")
for el in instagram_tags:
hashtag_id = el.get('hashtag__id')
label = Hashtag.objects.get(id=hashtag_id).label
sheet.write(row_index, 0, label)
sheet.write(row_index, 1, el.get('count'))
row_index += 1
else:
sheet.write(1, 0, "No hashtags in query")
if 'twitter' in instance:
# TwitterPublication
logger.info("[write_to_excel_perf]> Writting Twitter publications..")
sheet = book.add_worksheet('Twitter Media')
titles = ["City", "Date", "Twitter Id", "Twitter URL", "caption", "likes",
"author", "lat", "lng"]
i = 0
for title in titles:
sheet.write(0, i, title)
i += 1
row_index = 1
twitter_publications = twitter_publications.select_related('location__spot__city', 'author', 'location')
for el in twitter_publications:
city = el.location.spot.city.name if el.location is not None and el.location.spot.city is not None else "Undefined"
publication_date = el.publication_date.strftime("%d/%m/%Y %H:%M")
username = el.author.username if el.author is not None else "Undefined"
location_lat = el.location.position.y if el.location is not None else "Undefined"
location_lng = el.location.position.x if el.location is not None else "Undefined"
row = [city, publication_date, el.twitterID, el.twitter_url, el.caption, el.likes,
username, location_lat, location_lng]
column_index = 0
for value in row:
sheet.write(row_index, column_index, value)
column_index += 1
row_index += 1
# Adding tag page
sheet = book.add_worksheet('Twitter Tags')
titles = ["Hashtag", "Quantity"]
i = 0
for title in titles:
sheet.write(0, i, title)
i += 1
row_index = 1
if twitter_tags is not None:
logger.info("[write_to_excel_perf]> Writting Twitter hashtags..")
for el in twitter_tags:
hashtag_id = el.get('hashtag__id')
label = TwitterHashtag.objects.get(id=hashtag_id).label
sheet.write(row_index, 0, label)
sheet.write(row_index, 1, el.get('count'))
row_index += 1
else:
sheet.write(1, 0, "No hashtags in query")
book.close()
logger.info("[write_to_excel_perf]> Export file generated sucessfully.")
return book
答案 0 :(得分：2)
我尝试使用名为
constant_memory的参数，但它似乎没有什么区别。
应该这样做。如XlsxWriter Documentation所示，constant_memory选项可使内存使用量保持不变且小。
因此，如果它对您的应用程序没有任何影响，那么可能问题不在于XlsxWriter，而其他东西正在消耗内存。
您是否可以通过注释掉worksheet.write()的所有来电并再次运行测试来验证这一点。