to keep all users in memory? ??? Vasiliki Kalavri | Boston University 2020 We can use a hash function h to hash the user name (or IP) and select queries only when h(user) = 0. 13 In general: We can b1, …, b9. • select the query if the user hash value is in b0, b1, or b2. ??? Vasiliki Kalavri | Boston University 2020 We can use a hash function h to hash the user name (or IP) and select queries example, to get a 30% sample: • use 10 buckets, b0, b1, …, b9. • select the query if the user hash value is in b0, b1, or b2. How can we limit the sample size from growing indefinitely? ??? Vasiliki

3 Example use-case: Distinct users visiting one or multiple webpages Naive solution: maintain a hash table ??? Vasiliki Kalavri | Boston University 2020 How can we count the number of distinct elements or multiple webpages Naive solution: maintain a hash table Convert the stream into a multi-set of uniformly distributed random numbers using a hash function. ??? Vasiliki Kalavri | Boston University visiting one or multiple webpages Naive solution: maintain a hash table The more different elements we encounter in the stream, the more different hash values we shall see. Convert the stream into a multi-set

Sensitive Information 002 Medium Default Production Profile Not Sufficiently Hardened 003 Medium Weak Hash Used for Integrity 009 Medium Go Trace Profiling Enabled By Default 013 Medium Permissive Kubernetes ig-profiles/ 14 | Google Istio Security Assessment Google / NCC Group Confidential Finding Weak Hash Used for Integrity Risk Medium Impact: Medium, Exploitability: Low Identifier NCC-GOIST2005-009 instructions into the cluster. Description A cryptographic hash is a function which takes a string of bytes and returns a small, fixed-size value. Hash functions guarantee that the same input always results in the

Requirements for Cryptographic Modules 12/3/2002 [140AA] FIPS 140-2 Annex A: Approved Security Functions 6/10/2019 [140AC] FIPS 140-2 Annex C: Approved Random Number Generators 6/10/2019 [140AD] 1, Recommendation for Existing Application-Specific Key Derivation Functions 12/23/2011 [FIPS 180-4] FIPS 180-4, Secure Hash Standard (SHS) 8/4/2015 [FIPS 186-4] FIPS 186-4, Digital Signature 197] FIPS 197, Advanced Encryption Standard (AES) 11/26/2001 [FIPS 198-1] FIPS 198-1, The Keyed Hash Message Authentication Code (HMAC) 7/16/2008 FIPS 140-2 Security Policy Rancher Kubernetes

ring using the same hash function. Consistent hashing ??? Vasiliki Kalavri | Boston University 2020 n1 n3 n2 0 2128 Nodes and data are mapped to a ring using the same hash function. ei: | Boston University 2020 n1 n3 n2 0 2128 Nodes and data are mapped to a ring using the same hash function. ei: h ek: h Consistent hashing ??? Vasiliki Kalavri | Boston University nodes. n4 In practice, each node is mapped to multiple points on the ring using multiple hash functions. Consistent hashing ??? Vasiliki Kalavri | Boston University 2020 n1 n3 n2 0 2128 When

(GH28250) • Implemented pandas.core.window.Window.var() and pandas.core.window.Window. std() functions (GH26597) • Added encoding argument to DataFrame.to_string() for non-ascii text (GH28766) • Added testing module has been deprecated. Use the public API in pandas.testing documented at Testing functions (GH16232). • pandas.SparseArray has been deprecated. Use pandas.arrays.SparseArray (arrays. SparseArray) when grouping by a categorical column (GH28787) • Remove error raised due to duplicated input functions in named aggregation in DataFrame.groupby() and Series.groupby(). Previously error will be raised

known as “named aggregation”, for naming the output columns when applying multiple aggregation functions to specific columns (GH18366, GH26512). In [1]: animals = pd.DataFrame({'kind': ['cat', 'dog', groupby objects as well. Because there’s no need for column selection, the values can just be the functions to apply In [5]: animals.groupby("kind").height.agg( ...: min_height="min", ...: max_height="max" for more. 1.1.2 Groupby Aggregation with multiple lambdas You can now provide multiple lambda functions to a list-like aggregation in pandas.core.groupby.GroupBy. agg (GH26430). In [6]: animals.groupby('kind')

known as “named aggregation”, for naming the output columns when applying multiple aggregation functions to specific columns (GH18366, GH26512). In [1]: animals = pd.DataFrame({'kind': ['cat', 'dog', groupby objects as well. Because there’s no need for column selection, the values can just be the functions to apply In [5]: animals.groupby("kind").height.agg( ...: min_height="min", ...: max_height="max" for more. 1.1.2 Groupby Aggregation with multiple lambdas You can now provide multiple lambda functions to a list-like aggregation in pandas.core.groupby.GroupBy. agg (GH26430). In [6]: animals.groupby('kind')

. . . . . . . . . 658 2.15.1 Statistical functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 658 2.15.2 Window functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 952 3.2 General functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 954 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1251 3.3.5 Binary operator functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1252 3.3.6 Function application

. . . . . . . . . 658 2.15.1 Statistical functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 658 2.15.2 Window functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 951 3.2 General functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 954 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1251 3.3.5 Binary operator functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1252 3.3.6 Function application