如何从s3存储桶中仅读取5条记录并在不获取csv文件的所有数据的情况下返回它

Question

Hello guys I know lots of similar questions i'll find here but i have a code which is executing properly which is returning five records also my query is how should i only read the entire file and atlast return with desire rows just supose i have csv file which have size in gb so i don't want to return the entire gb file data for getting only 5 records so please tell me how should i get it....Please if possible explain my code if it is not good why it is not good.. code:

import boto3
from botocore.client import Config
import pandas as pd

ACCESS_KEY_ID = 'something'
ACCESS_SECRET_KEY = 'something'
BUCKET_NAME = 'something'
Filename='dataRepository/source/MergedSeedData(Parts_skills_Durations).csv'

client = boto3.client("s3",
                     aws_access_key_id=ACCESS_KEY_ID,
                     aws_secret_access_key=ACCESS_SECRET_KEY)
obj = client.get_object(Bucket=BUCKET_NAME, Key=Filename)
Data = pd.read_csv(obj['Body'])
# data1 = Data.columns
# return data1
Data=Data.head(5)
print(Data)

This my code which is running fine also getting the 5 records from s3 bucket but i have explained it what i'm looking for any other query feel free to text me...thnxx in advance

Answer 1

You can use the pandas capability of reading a file in chunks , just loading as much data as you need.

data_iter = pd.read_csv(obj['Body'], chunksize = 5)
data = data_iter.get_chunk()
print(data)

Answer 2

You can use a HTTP Range: header ( see RFC 2616 ), which take a byte range argument. S3 APIs have a provision for this and this will help you to NOT read/download the whole S3 file.

Sample code:

import boto3
obj = boto3.resource('s3').Object('bucket101', 'my.csv')
record_stream = obj.get(Range='bytes=0-1000')['Body']
print(record_stream.read())

This will return only the byte_range_data provided in the header.

But you will need to modify this to convert the string into Dataframe . Maybe read + join for the \\t and \\n present in the string coming from the .csv file