在AWS Glue中,'Rewind Job Bookmark”是一种用于把作业恢复到先前的检查点或位置的机制。可以通过在AWS Glue作业中激活bookmark设置来启用它,并将其设置为true。默认情况下,bookmark设置是禁用的。
使用以下代码示例即可将bookmark设置为true:
import sys
from awsglue.transforms import *
from awsglue.utils import getResolvedOptions
from awsglue.dynamicframe import DynamicFrame
from awsglue.context import GlueContext
from awsglue.job import Job
glueContext = GlueContext(SparkContext.getOrCreate())
# Set bookmark option to true
glueContext.setConf("glue.job.bookmark.option", "job-bookmark-enable")
job = Job(glueContext)
# other job configurations and logic
启用bookmark设置之后,可以按如下方式使用'Rewind Job Bookmark”:
job.init(args['JOB_NAME'], args)
# Add code to read input and perform transformations
# Also, add code to check the bookmark status
# Check if bookmark is set for the current job.
isBookmarkSet = glueContext.isBookmarkJobEnabled()
# If bookmark is set, get the latest bookmark for the job.
# This will return None if there is no bookmark available.
latestBookmark = glueContext.getJobBookmark(job)
# If the latest bookmark is available, pass it as an argument to the job.
if latestBookmark is not None:
job.init(args['JOB_NAME'], args, latestBookmark)
# Add code to write output and commit bookmark if required.
在上述代码中,首先检查bookmark设置是否启用。然后,获取最新的bookmark,如果bookmark可用,则将其传递给作业。这样,作业会将其恢复到最后一个检查点或位置。如果在后续运行中需要更新bookmark,则可以使用glueContext.commitJobBookmark(job)
函数进行提交。
总之,通过启用bookmark设置并使用'Rewind Job Bookmark”机制,可以在AWS Glue中实现有状态的ETL作业。