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110 lines
3.5 KiB
110 lines
3.5 KiB
#!/home/alpcentaur/ProjektA/PrototypeWebApp/venv/bin/python3.5
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import argparse
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import os
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import boto
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from boto.compat import json
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from boto.compat import six
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from boto.dynamodb.schema import Schema
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DESCRIPTION = """Load data into one or more DynamoDB tables.
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For each table, data is read from two files:
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- {table_name}.metadata for the table's name, schema and provisioned
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throughput (only required if creating the table).
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- {table_name}.data for the table's actual contents.
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Both files are searched for in the current directory. To read them from
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somewhere else, use the --in-dir parameter.
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This program does not wipe the tables prior to loading data. However, any
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items present in the data files will overwrite the table's contents.
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"""
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def _json_iterload(fd):
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"""Lazily load newline-separated JSON objects from a file-like object."""
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buffer = ""
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eof = False
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while not eof:
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try:
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# Add a line to the buffer
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buffer += fd.next()
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except StopIteration:
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# We can't let that exception bubble up, otherwise the last
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# object in the file will never be decoded.
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eof = True
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try:
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# Try to decode a JSON object.
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json_object = json.loads(buffer.strip())
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# Success: clear the buffer (everything was decoded).
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buffer = ""
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except ValueError:
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if eof and buffer.strip():
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# No more lines to load and the buffer contains something other
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# than whitespace: the file is, in fact, malformed.
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raise
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# We couldn't decode a complete JSON object: load more lines.
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continue
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yield json_object
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def create_table(metadata_fd):
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"""Create a table from a metadata file-like object."""
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def load_table(table, in_fd):
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"""Load items into a table from a file-like object."""
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for i in _json_iterload(in_fd):
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# Convert lists back to sets.
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data = {}
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for k, v in six.iteritems(i):
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if isinstance(v, list):
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data[k] = set(v)
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else:
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data[k] = v
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table.new_item(attrs=data).put()
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def dynamodb_load(tables, in_dir, create_tables):
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conn = boto.connect_dynamodb()
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for t in tables:
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metadata_file = os.path.join(in_dir, "%s.metadata" % t)
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data_file = os.path.join(in_dir, "%s.data" % t)
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if create_tables:
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with open(metadata_file) as meta_fd:
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metadata = json.load(meta_fd)
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table = conn.create_table(
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name=t,
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schema=Schema(metadata["schema"]),
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read_units=metadata["read_units"],
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write_units=metadata["write_units"],
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)
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table.refresh(wait_for_active=True)
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else:
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table = conn.get_table(t)
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with open(data_file) as in_fd:
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load_table(table, in_fd)
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(
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prog="dynamodb_load",
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description=DESCRIPTION
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)
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parser.add_argument(
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"--create-tables",
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action="store_true",
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help="Create the tables if they don't exist already (without this flag, attempts to load data into non-existing tables fail)."
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)
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parser.add_argument("--in-dir", default=".")
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parser.add_argument("tables", metavar="TABLES", nargs="+")
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namespace = parser.parse_args()
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dynamodb_load(namespace.tables, namespace.in_dir, namespace.create_tables)
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