Faster Azure blob name search with python?

问题

I have a list of file names that I need to search on Azure. Right now as a noob I am looping over each blob names and comparing strings but I think there has to be easiest and fast way to get this done. The current solution is making my HTTP response very slow.

def ifblob_exists(self, filename):
        try:
            container_name = 'xxx'
            AZURE_KEY = 'xxx'
            SAS_KEY = 'xxx'
            ACCOUNT_NAME = 'xxx'
            block_blob_service = BlockBlobService(account_name= ACCOUNT_NAME, account_key= None, sas_token = SAS_KEY, socket_timeout= 10000)

            generator = block_blob_service.list_blobs(container_name)
            for blob in generator:
                if filename == blob.name:
                    print("\t Blob exists :"+" "+blob.name)
                    return True
                else:
                    print('Blob does not exists '+filename)
                    return False
        except Exception as e:
            print(e)

回答1:

Listing all blobs is very costly operation inside the Azure Storage infrastructure because it translates into a full scan.

Find below an example to efficiently check if the blob (e.g. filename in your case) exists or not in a given container:

from azure.storage.blob import BlockBlobService
from datetime import datetime

def check_if_blob_exists(container_name: str, blob_names: []):
    start_time = datetime.now()

    if not container_name or container_name.isspace():
        raise ValueError("Container name cannot be none, empty or whitespace.")

    if not blob_names:
        raise ValueError("Block blob names cannot be none.")

        block_blob_service = BlockBlobService(account_name="{Storage Account Name}", account_key="{Storage Account Key}")

    for blob_name in blob_names:
        if block_blob_service.exists(container_name, blob_name):
            print("\nBlob '{0}' found!".format(blob_name));
        else:
            print("\nBlob '{0}' NOT found!".format(blob_name));

    end_time = datetime.now()

    print("\n***** Elapsed Time => {0} *****".format(end_time - start_time))

if __name__ == "__main__":
    blob_names = []

    # Exists
    blob_names.append("eula.1028.txt")
    blob_names.append("eula.1031.txt")
    blob_names.append("eula.1033.txt")
    blob_names.append("eula.1036.txt")
    blob_names.append("eula.1040.txt")

    # Don't exist
    blob_names.append("blob1")
    blob_names.append("blob2")
    blob_names.append("blob3")
    blob_names.append("blob4")

    check_if_blob_exists("containername", blob_names)

Find below a screenshot of a quick execution test from my laptop from West US (~150 Mbps of Download, ~3.22 Mbps of Upload, per Google Speed Test) checking if 9 blobs exists in a LRS Storage Account in West US as well.

回答2:

Please use exists method in azure storage python sdk.

def ifblob_exists(filename):
    try:
        container_name = '***'

        block_blob_service = BlockBlobService(account_name=accountName, account_key=accountKey,
                                              socket_timeout=10000)

        isExist = block_blob_service.exists(container_name, filename)
        if isExist:
            print("\t Blob exists :" + " " + filename)
        else:
            print("\t Blob exists :" + " " + filename)

Surely, if you have list of filename, you need to loop call above function at least.

Hope it helps you.

来源：https://stackoverflow.com/questions/51166611/faster-azure-blob-name-search-with-python