GitHub - druid-io/pydruid: A Python connector for Druid (original) (raw)

pydruid

pydruid exposes a simple API to create, execute, and analyze Druid queries. pydruid can parse query results into Pandas DataFrame objects for subsequent data analysis -- this offers a tight integration between Druid, the SciPy stack (for scientific computing) and scikit-learn (for machine learning). pydruid can export query results into TSV or JSON for further processing with your favorite tool, e.g., R, Julia, Matlab, Excel. It provides both synchronous and asynchronous clients.

Additionally, pydruid implements the Python DB API 2.0, a SQLAlchemy dialect, and a provides a command line interface to interact with Druid.

To install:

pip install pydruid

or, if you intend to use asynchronous client

pip install pydruid[async]

or, if you intend to export query results into pandas

pip install pydruid[pandas]

or, if you intend to do both

pip install pydruid[async, pandas]

or, if you want to use the SQLAlchemy engine

pip install pydruid[sqlalchemy]

or, if you want to use the CLI

pip install pydruid[cli]

Documentation: https://pythonhosted.org/pydruid/.

examples

The following exampes show how to execute and analyze the results of three types of queries: timeseries, topN, and groupby. We will use these queries to ask simple questions about twitter's public data set.

timeseries

What was the average tweet length, per day, surrounding the 2014 Sochi olympics?

from pydruid.client import * from pylab import plt

query = PyDruid(druid_url_goes_here, 'druid/v2')

ts = query.timeseries( datasource='twitterstream', granularity='day', intervals='2014-02-02/p4w', aggregations={'length': doublesum('tweet_length'), 'count': doublesum('count')}, post_aggregations={'avg_tweet_length': (Field('length') / Field('count'))}, filter=Dimension('first_hashtag') == 'sochi2014' ) df = query.export_pandas() df['timestamp'] = df['timestamp'].map(lambda x: x.split('T')[0]) df.plot(x='timestamp', y='avg_tweet_length', ylim=(80, 140), rot=20, title='Sochi 2014') plt.ylabel('avg tweet length (chars)') plt.show()

topN

Who were the top ten mentions (@user_name) during the 2014 Oscars?

top = query.topn( datasource='twitterstream', granularity='all', intervals='2014-03-03/p1d', # utc time of 2014 oscars aggregations={'count': doublesum('count')}, dimension='user_mention_name', filter=(Dimension('user_lang') == 'en') & (Dimension('first_hashtag') == 'oscars') & (Dimension('user_time_zone') == 'Pacific Time (US & Canada)') & ~(Dimension('user_mention_name') == 'No Mention'), metric='count', threshold=10 )

df = query.export_pandas() print df

count timestamp user_mention_name 0 1303 2014-03-03T00:00:00.000Z TheEllenShow 1 44 2014-03-03T00:00:00.000Z TheAcademy 2 21 2014-03-03T00:00:00.000Z MTV 3 21 2014-03-03T00:00:00.000Z peoplemag 4 17 2014-03-03T00:00:00.000Z THR 5 16 2014-03-03T00:00:00.000Z ItsQueenElsa 6 16 2014-03-03T00:00:00.000Z eonline 7 15 2014-03-03T00:00:00.000Z PerezHilton 8 14 2014-03-03T00:00:00.000Z realjohngreen 9 12 2014-03-03T00:00:00.000Z KevinSpacey

groupby

What does the social network of users replying to other users look like?

from igraph import * from cairo import * from pandas import concat

group = query.groupby( datasource='twitterstream', granularity='hour', intervals='2013-10-04/pt12h', dimensions=["user_name", "reply_to_name"], filter=(~(Dimension("reply_to_name") == "Not A Reply")) & (Dimension("user_location") == "California"), aggregations={"count": doublesum("count")} )

df = query.export_pandas()

map names to categorical variables with a lookup table

names = concat([df['user_name'], df['reply_to_name']]).unique() nameLookup = dict([pair[::-1] for pair in enumerate(names)]) df['user_name_lookup'] = df['user_name'].map(nameLookup.get) df['reply_to_name_lookup'] = df['reply_to_name'].map(nameLookup.get)

create the graph with igraph

g = Graph(len(names), directed=False) vertices = zip(df['user_name_lookup'], df['reply_to_name_lookup']) g.vs["name"] = names g.add_edges(vertices) layout = g.layout_fruchterman_reingold() plot(g, "tweets.png", layout=layout, vertex_size=2, bbox=(400, 400), margin=25, edge_width=1, vertex_color="blue")

asynchronous client

pydruid.async_client.AsyncPyDruid implements an asynchronous client. To achieve that, it utilizes an asynchronous HTTP client from Tornado framework. The asynchronous client is suitable for use with async frameworks such as Tornado and provides much better performance at scale. It lets you serve multiple requests at the same time, without blocking on Druid executing your queries.

example

from tornado import gen from pydruid.async_client import AsyncPyDruid from pydruid.utils.aggregators import longsum from pydruid.utils.filters import Dimension

client = AsyncPyDruid(url_to_druid_broker, 'druid/v2')

@gen.coroutine def your_asynchronous_method_serving_top10_mentions_for_day(day top_mentions = yield client.topn( datasource='twitterstream', granularity='all', intervals="%s/p1d" % (day, ), aggregations={'count': doublesum('count')}, dimension='user_mention_name', filter=(Dimension('user_lang') == 'en') & (Dimension('first_hashtag') == 'oscars') & (Dimension('user_time_zone') == 'Pacific Time (US & Canada)') & ~(Dimension('user_mention_name') == 'No Mention'), metric='count', threshold=10)

# asynchronously return results
# can be simply ```return top_mentions``` in python 3.x
raise gen.Return(top_mentions)

thetaSketches

Theta sketch Post aggregators are built slightly differently to normal Post Aggregators, as they have different operators. Note: you must have the druid-datasketches extension loaded into your Druid cluster in order to use these. See the Druid datasketches documentation for details.

from pydruid.client import * from pydruid.utils import aggregators from pydruid.utils import filters from pydruid.utils import postaggregator

query = PyDruid(url_to_druid_broker, 'druid/v2') ts = query.groupby( datasource='test_datasource', granularity='all', intervals='2016-09-01/P1M', filter = ( filters.Dimension('product').in_(['product_A', 'product_B'])), aggregations={ 'product_A_users': aggregators.filtered( filters.Dimension('product') == 'product_A', aggregators.thetasketch('user_id') ), 'product_B_users': aggregators.filtered( filters.Dimension('product') == 'product_B', aggregators.thetasketch('user_id') ) }, post_aggregations={ 'both_A_and_B': postaggregator.ThetaSketchEstimate( postaggregator.ThetaSketch('product_A_users') & postaggregator.ThetaSketch('product_B_users') ) } )

DB API

from pydruid.db import connect

conn = connect(host='localhost', port=8082, path='/druid/v2/sql/', scheme='http') curs = conn.cursor() curs.execute(""" SELECT place, CAST(REGEXP_EXTRACT(place, '(.),', 1) AS FLOAT) AS lat, CAST(REGEXP_EXTRACT(place, ',(.)', 1) AS FLOAT) AS lon FROM places LIMIT 10 """) for row in curs: print(row)

SQLAlchemy

from sqlalchemy import * from sqlalchemy.engine import create_engine from sqlalchemy.schema import *

engine = create_engine('druid://localhost:8082/druid/v2/sql/') # uses HTTP by default :(

engine = create_engine('druid+http://localhost:8082/druid/v2/sql/')

engine = create_engine('druid+https://localhost:8082/druid/v2/sql/')

places = Table('places', MetaData(bind=engine), autoload=True) print(select([func.count('*')], from_obj=places).scalar())

Column headers

In version 0.13.0 Druid SQL added support for including the column names in the response which can be requested via the "header" field in the request. This helps to ensure that the cursor description is defined (which is a requirement for SQLAlchemy query statements) regardless on whether the result set contains any rows. Historically this was problematic for result sets which contained no rows at one could not infer the expected column names.

Enabling the header can be configured via the SQLAlchemy URI by using the query parameter, i.e.,

engine = create_engine('druid://localhost:8082/druid/v2/sql?header=true')

Note the current default is false to ensure backwards compatibility but should be set to true for Druid versions >= 0.13.0.

Command line

$ pydruid http://localhost:8082/druid/v2/sql/ > SELECT COUNT(*) AS cnt FROM places cnt

12345 > SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES; TABLE_NAME

test_table COLUMNS SCHEMATA TABLES

BYE; GoodBye!

Contributing

Contributions are welcomed of course. We like to use black and flake8.

pip install -r requirements-dev.txt # installs useful dev deps pre-commit install # installs useful commit hooks