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logseq/bak/pages/总复习2023t1/2023-06-14T07_11_54.910Z.Desktop.md → logseq/bak/pages/总复习2023t1/2023-06-15T01_27_27.434Z.Desktop.md
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@ -870,49 +870,51 @@
:LOGBOOK:
CLOCK: [2023-06-04 Sun 16:27:23]--[2023-06-04 Sun 16:54:55] => 00:27:32
:END:
- LATER Block 1
- DONE Block 1
deck:: 2023t1/database
collapsed:: true
- DONE DBMS
- Database is :-> a shared collection of logically related data (and a description of this data), designed to meet the information needs of an organization.
id:: 64895ec0-d724-4159-a95d-657afd171c29
id:: 648974ba-3221-48b2-8f9c-2d9275174f48
- Table :-> A collection of related data organized into rows (also called records) and columns (also called fields).
id:: 64895ec0-2290-4f62-8711-45e99803c82e
id:: 648974ba-7b5a-4cff-8d21-3bcc7e0c1fe8
- Row/Record :-> A single set of data in a table, representing a specific instance or entity.
id:: 64895ec0-12a9-402d-8c1d-64c40e169bb2
id:: 648974ba-d192-4027-945a-9c6113ac218f
- Column/Field :-> A specific attribute or data element within a table.
id:: 64895ec0-2aed-4aa8-a34f-446fd7715db6
id:: 648974ba-89e7-434a-b242-68a1ea3f7f6b
- Primary Key :-> A unique identifier for each row/record in a table. It ensures the integrity and uniqueness of the data.
id:: 64895ec0-7339-477c-b765-b12fd18e9df4
id:: 648974ba-611e-4d5c-849b-9cd57b7bddb9
- Foreign Key :-> A field in one table that refers to the primary key in another table, establishing a relationship between the two tables.
id:: 64895ec0-75e5-4378-aa9c-b4af6d7d37c9
id:: 648974ba-bc0d-4b78-a8cb-7a081ca1b2ac
- Relationship :-> The connection between tables based on common data values, such as primary and foreign keys.
id:: 64895ec0-ab80-4eed-bb91-0911b1954368
id:: 648974ba-851d-42a7-95c1-2619fed22d3a
- Normalization :-> The process of organizing and structuring a database design to eliminate redundancy and improve data integrity.
id:: 64895ec0-8b79-4172-8cad-25e4edada659
id:: 648974ba-53b0-4176-b67b-cd51d1ea09c6
- Index :-> A data structure that improves the retrieval speed of data from a database table by creating a quick reference to the location of the data.
id:: 64895ec0-f3cd-4625-b2ca-6e94f870b34d
id:: 648974ba-2246-42c3-aa0c-7609107af7c5
- Query :-> A request for data or information from a database, usually written using Structured Query Language (SQL).
id:: 64895ec0-df79-46a4-8fb2-09b34a414c9c
id:: 648974ba-4b3e-4f99-90fd-b4c9a1a43a53
- SQL (Structured Query Language) :-> A programming language used to manage and manipulate relational databases. It allows you to create, modify, and retrieve data from databases.
id:: 64895ec0-4de4-4cfd-8042-7f92458a8a26
id:: 648974ba-a844-4e21-a1ca-e0b26668f1b7
- CRUD Operations :-> An acronym for Create, Read, Update, and Delete operations, which are the basic operations used to manage data in a database.
id:: 64895ec0-77ed-4253-947e-2a54c4235a05
id:: 648974ba-34d4-49df-91c9-b44b018120c6
- ACID (Atomicity, Consistency, Isolation, Durability) :-> A set of properties that guarantee the reliability and integrity of database transactions.
id:: 64895ec0-e18b-4340-8a24-98b2cbaec1fd
id:: 648974ba-4174-45b7-8903-38ffea39a200
- Data Integrity :-> The accuracy, consistency, and reliability of data stored in a database.
id:: 64895ec0-023b-47dc-96bd-7a4c52fd9717
id:: 648974ba-7797-4a43-b644-f0780da5121b
- Database Schema :-> The structure or blueprint of a database, defining the tables, fields, relationships, and constraints.
id:: 64895ec0-0c9b-49fc-923d-264841105690
id:: 648974ba-7b5c-45d1-ac86-ef7211c9672a
- Database Management System (DBMS) :-> Software that provides an interface to interact with databases, managing their creation, modification, and retrieval.
id:: 64895ec0-60c1-468f-bc13-bd65c736a682
id:: 648974ba-627d-463c-9237-56777d45b8af
- DONE basic concepts of Relational model
- A data model :- > a graphical description of the
components of database.
- A relation, is :-> a two-dimensional table arranged in columns and rows.
id:: 64895ec0-a8ef-4e61-8e31-ce2b319a459b
id:: 648974ba-40ec-4600-af39-d438a5f75339
- A relational database is :-> a collection of relations.
id:: 64895ec0-4f99-4abd-a0f1-a0707ff20bd7
id:: 648974ba-c76d-4f2b-a8ad-ef1ad3a16b2c
- Candidate Key #flashcard
id:: 64895ec0-44d2-4816-9201-492149a1e26e
id:: 648974ba-a2f3-43a1-a5ea-c170c68314e1
- A set of attributes that uniquely identifies a tuple within a
relation.
- Uniqueness : In each tuple, candidate key uniquely identify
@ -920,45 +922,44 @@
- Irreducibility: No proper subset of the candidate key has the
uniqueness property.
- Primary Key #flashcard
id:: 64895ec0-057c-49f6-8fd9-0fc599e49e0a
id:: 648974ba-c5dc-44cb-8894-8f5838714f2a
- Candidate key selected to identify tuples uniquely within
relation.
- Foreign Key #flashcard
id:: 64895ec0-2bf4-4bf5-92f3-b266cfcce167
id:: 648974ba-da05-48b6-aded-75d1ea5f1342
- Attribute, or set of attributes, within one relation that
matches candidate key of some (possibly same) relation.
- Composite Key #flashcard
id:: 64895ec0-7b2e-4031-97ca-157c1864ac1c
id:: 648974ba-7242-4c00-b67b-5418c3f71e77
- A candidate key that consists of two or more attributes.
- Recursive Relationship #flashcard
id:: 64895ec0-96f6-4a17-8d67-ddd8c7679066
id:: 648974ba-eb07-4e80-a1c3-87555fb04d1a
- Relationship type where same entity type participates
more than once in different roles.
- Multiplicity :-> number (or range) of possible
id:: 64895ec0-3514-4e82-acf6-f25238116bb7
id:: 648974ba-5d96-4c64-a1b0-e9e61aa3563a
occurrences of an entity type that may relate to a
single occurrence of an associated entity type
through a particular relationship.
![image.png](../assets/image_1686723218703_0.png)
- Cardinality #flashcard
id:: 64895ec0-4ad7-43f2-80fc-489bc0a07ec1
id:: 648974ba-b24d-40a3-8669-9dbc85dedaf7
- Describes {{c1 maximum}} number of possible relationship occurrences for an entity participating in a given relationship type.
id:: 64895ec0-e8d2-47e1-97b8-d81ed8d62f64
id:: 648974ba-ea33-489d-bb7b-1951685babd0
- Participation #flashcard
id:: 64895ec0-c4c3-400e-9cb6-08f722328773
id:: 648974ba-6dc5-4805-9dfd-7db5a83efe3f
- Determines whether all or only some entity occurrences participate in a relationship.
- Gives the minimum number for an entity occurrences participating in a given relationship type.
- Ternary relationship #flashcard
id:: 64895ec0-0897-4857-b763-0349ae186d62
id:: 648974ba-9b7a-4543-b243-e7a78cfc8175
- a ternary relationship is not the same as three binary relationships!
- LATER basic concepts associated with Entity-Relationship(ER) model.
- DONE basic concepts associated with Entity-Relationship(ER) model.
- LATER Forming sql queries
collapsed:: true
- DONE Review relational algebra https://www.geeksforgeeks.org/introduction-of-relational-algebra-in-dbms/
- LATER review lab2
- LATER SQL join
- LATER Block 2
- LATER EER
- DONE Block 2
- DONE EER
- Most useful additional concept of EER model:
specialization/generalization.
- Specialization
@ -973,6 +974,7 @@
id:: 64896085-645b-408f-b17a-109b6cd82aeb
specialization/generalization:
- participation constraints :-> Determines whether every member in superclass
id:: 6489683b-319a-4173-a55b-6fa3b2c09aeb
must participate as a member of a subclass.
- May be mandatory or optional. #flashcard
id:: 648960d0-ae7f-4452-a1b9-cab8a9b13443
@ -980,14 +982,10 @@
member of subclass
- Optional: member of superclass may be member
of subclass.
- disjoint constraints :-> Describes relationship between members of the
subclasses and indicates whether member of a
superclass can be a member of one, or more than
one, subclass. #flashcard
- Disjoint: member of superclass is member of at
most one subclass
- Disjoint: member of superclass is member of at
most one subclass
- disjoint constraints :-> Describes relationship between members of the subclasses and indicates whether member of a superclass can be a member of one, or more than one, subclass. #flashcard
id:: 6489683b-039f-4161-94b1-91177f713ee5
- Disjoint: member of superclass is member of at most one subclass (or)
- Nondisjoint: member of superclass can be member of more than one subclass (and)
- Superclass / Subclass
- Superclass :-> An entity type that includes one or more distinct
id:: 64895f2f-b868-46ec-9d80-7079eaf3197d
@ -1002,43 +1000,82 @@
- Subclass :-> A distinct subgrouping of occurrences of an entity
id:: 64895f39-d886-436b-9afe-ba75d37c8b45
type.
- When to use them? either one or both
1. There are attributes that apply to some (but
not all) instances of an entity.
2. The instances of a potential subclass
participate in a relationship unique to that
subclass.
- LATER designing ER diagram
- When to use them? either one or both #flashcard
id:: 6489683b-7d47-4246-afdf-83fdb35a00f6
- There are attributes that apply to some (but not all) instances of an entity.
- The instances of a potential subclass participate in a relationship unique to that subclass.
- DONE Designing databases
- Understand Database Design Methodology #flashcard
- Conceptual database design
- The process of constructing a model of the data used in an enterprise, independent of all physical considerations.
- Logical database design
- Maps the conceptual data model on to a logical model (e.g. relational), but independent of a particular DBMS and other physical considerations.
- Physical database design
- The process of producing a description of the implementation of the database (tailored to specific DBMS);
- general steps for Database Design Methodology. #flashcard
- Gather requirements
- Conceptual database design
- Logical database design
- Physical database design
- LATER SQL
- purpose and importance of SQL.
- retrieve data from database and formulate queries using SELECT and
- Use compound WHERE conditions.
- Sort query results using ORDER BY.
- Use aggregate functions.
- Group data using GROUP BY and HAVING.
- Join tables together.
- Use subqueries.
- DONE Block 3
collapsed:: true
- DONE DB transaction management
- DONE ACID (Atomicity, Consistency, Isolation, Durability): A set of properties that guarantee the reliability and integrity of database transactions.
- Atomicity: The property that ensures a transaction is treated as a single, indivisible unit of work. It either executes all its operations successfully or rolls back to the initial state if any operation fails.
- Consistency: The property that ensures a transaction transforms the database from one consistent state to another consistent state. It maintains data integrity and adheres to defined business rules.
- Isolation: The property that ensures concurrent transactions do not interfere with each other. Each transaction operates in isolation until it completes, preventing interference or conflicts.
- Durability: The property that ensures committed changes made by a transaction are permanently saved and will survive any subsequent system failures or crashes.
- DONE Deadlock and how it can be resolved. #flashcard
id:: 64841da4-d8ce-46f5-bbe6-4dee620cde75
- A deadlock is a situation in which two or more transactions are unable
to proceed because each is waiting for a resource held by the other,
resulting in a circular dependency and a system halt. It is a form of
resource contention that can occur in concurrent systems, including
database management systems.
- Example:
- Cascading rollback #flashcard
id:: 64897f0b-dda6-4cc3-a9c3-cf630bcb0658
- Cascading Rollback: a transaction (T1) causes a
failure and a rollback must be performed. Other
transactions dependent on T1's actions must also
be rollbacked, thus causing a cascading effect.
- One transaction's failure causes many to fail.
- DONE ACID (Atomicity, Consistency, Isolation, Durability): A set of properties that guarantee the reliability and integrity of database transactions. #flashcard
id:: 64841da4-0055-4d34-9f61-1402ff068ec7
collapsed:: true
- Atomicity: :-> The property that ensures a transaction is treated as a single, indivisible unit of work. It either executes all its operations successfully or rolls back to the initial state if any operation fails.
id:: 64841d38-4ea9-4b76-8585-8b9de23915da
- Consistency: :-> The property that ensures a transaction transforms the database from one consistent state to another consistent state. It maintains data integrity and adheres to defined business rules.
id:: 64841d38-2854-4dfb-8f21-0013fca66a0a
- Isolation: :-> The property that ensures concurrent transactions do not interfere with each other. Each transaction operates in isolation until it completes, preventing interference or conflicts.
id:: 64841d38-fd2b-435e-bd45-3bf487a74b6f
- Durability: :-> The property that ensures committed changes made by a transaction are permanently saved and will survive any subsequent system failures or crashes.
id:: 64841d38-950c-431e-8f28-ece98e230554
- DONE Concurrency control
- DONE Meaning of serialisability.
- DONE How locking can ensure serialisability.
- DONE Meaning of serialisability. #flashcard
id:: 648428e1-5136-4d15-97c0-12087085b47f
- The objective of serialisability is to find nonserial schedules that are equivalent to some serial schedule. Such a schedule is called serialisable.
- DONE How locking can ensure serialisability. #flashcard
id:: 64841da4-8812-405f-b49a-69eec9a069d2
- Locking achieves serializability by using locks to control access to
shared resources (e.g., database objects like tables or rows) and
prevent conflicts between concurrent transactions.
- DONE 2PL
- DONE 2PL #flashcard
id:: 64841da4-eab4-40db-819f-249fe1437250
- In the 2PL protocol, transactions acquire and release locks on database
objects (e.g., tables, rows) in two distinct phases: the growing phase
and the shrinking phase.
- DONE Deadlock and how it can be resolved.
- A deadlock is a situation in which two or more transactions are unable
to proceed because each is waiting for a resource held by the other,
resulting in a circular dependency and a system halt. It is a form of
resource contention that can occur in concurrent systems, including
database management systems.
- DONE How timestamping can ensure serialisability.
- DONE How timestamping can ensure serialisability. #flashcard
id:: 64842000-07a7-4439-8ce6-7789e0a3358d
- By using transaction timestamps and enforcing the read and write
validation checks, concurrency control mechanisms can ensure that
transactions are executed in a way that maintains data consistency and
serializability.
- DONE Recovery Control
- ==DONE Recovery Control==
- DONE Some causes of database failure.
- System crashes, resulting in loss of main memory.
- Power failures
@ -1047,20 +1084,23 @@
- Natural physical disasters.
- User mistakes.
- Sabotage.
- DONE Purpose of transaction log file.
- DONE Purpose of transaction log file. #flashcard
id:: 64841f8f-5a9e-4f22-8f51-47931937998a
- Contains information about all updates to
database:
- Transaction records.
- Checkpoint records.
- Often used for other purposes (for example, auditing).
- For autiding
- DONE Purpose of checkpointing.
- DONE Purpose of checkpointing. #flashcard
id:: 64841f91-1d24-49f6-9f83-7c8b565c647f
- When failure occurs, redo all transactions that
committed since the checkpoint and undo all
transactions active at time of crash.
- DONE Normalization
background-color:: yellow
- DONE Functional dependencies [g4g](https://www.geeksforgeeks.org/types-of-functional-dependencies-in-dbms/)
- DONE Functional dependencies [g4g](https://www.geeksforgeeks.org/types-of-functional-dependencies-in-dbms/) #flashcard
id:: 648428e1-e704-4e23-941d-af9833de6f93
- In a relational database management, functional dependency is a concept
that specifies the relationship between two sets of attributes where one
attribute determines the value of another attribute. It is denoted as **X → Y**, where the attribute set on the left side of the arrow, **X** is called **Determinant** , and **Y** is called the **Dependent**.
@ -1069,122 +1109,142 @@
CLOCK: [2023-06-01 Thu 17:38:55]--[2023-06-01 Thu 17:38:56] => 00:00:01
:END:
- DONE kinds of NF [tutorial](https://www.geeksforgeeks.org/normal-forms-in-dbms/)
- First Normal Form (1NF): This is the most basic level of
- First Normal Form (1NF): :-> This is the most basic level of
id:: 648974ba-7334-4e73-a0ae-6b8fc6ec99ab
normalization. In 1NF, each table cell should contain _only a single value, and each column should have a unique name_. The first normal form helps to eliminate duplicate data and simplify queries.
- Second Normal Form (2NF): 2NF eliminates redundant data by requiring that each _non-key attribute_ be dependent on the primary key. This means that _each column should be directly related to the primary key_, and not to other
- Second Normal Form (2NF): :-> 2NF eliminates redundant data by requiring that each _non-key attribute_ be ==dependent on the primary key==. This means that _each column should be directly related to the primary key_, and not to other
id:: 648974ba-cc9e-4cdf-a312-3af1bcab23f2
columns.
- Third Normal Form (3NF): 3NF builds on 2NF by requiring
that _all non-key attributes are independent of each other._ This means that each column should be directly related to the primary key, and not to any other columns in the same table.
- Boyce-Codd Normal Form (BCNF): BCNF is a stricter form of 3NF that ensures that each determinant in a table is a candidate key. In other words, BCNF ensures that _each non-key attribute is dependent only on the candidate key._
- Third Normal Form (3NF): :-> 3NF builds on 2NF by requiring
id:: 648974ba-f325-450e-aede-9a7d92bcf888
that _all non-key attributes are **independent** of each other._ This means that each column should be **directly related to the primary key**, and not to any other columns in the same table.
- Boyce-Codd Normal Form (BCNF): :-> BCNF is a stricter form of 3NF that ensures that each determinant in a table is a candidate key. In other words, BCNF ensures that _each non-key attribute is dependent **only on the candidate key**._
id:: 64842000-c15a-4b8f-95c3-d6c6e49e4af0
- Fourth Normal Form (4NF): 4NF is a further refinement of BCNF that ensures that _a table does not contain any multi-valued dependencies._
- Fifth Normal Form (5NF): 5NF is the highest level of normalization and involves decomposing a table into smaller tables to _remove data redundancy and improve data integrity._
- DONE Block 4
- Anomaly
- Update Anomalies #flashcard
- Insertion anomalies
- If there is a new row inserted in the table and it creates the
inconsistency in the table then it is called the insertion anomaly. For
example, if in the above table, we create a new row of a worker, and if
it is not allocated to any department then we cannot insert it in the
table so, it will create an insertion anomaly.
- Deletion anomalies
- If we delete some rows from the table and if any other information or
data which is required is also deleted from the database, this is called
the deletion anomaly in the database. For example, in the above table,
if we want to delete the department number ECT669 then the details of
Rajesh will also be deleted since Rajesh's details are dependent on the
row of ECT669. So, there will be deletion anomalies in the table.
- Modification anomalies
- When we update some rows in the table, and if it leads to the
inconsistency of the table then this anomaly occurs. This type of
anomaly is known as an updation anomaly. In the above table, if we want
to update the address of Ramesh then we will have to update all the rows
where Ramesh is present. If during the update we miss any single row,
then there will be two addresses of Ramesh, which will lead to
inconsistent and wrong databases.
- LATER Block 4
- DONE Distributed DBMS
collapsed:: true
- DONE client server arch
collapsed:: true
- DONE client server arch #flashcard
id:: 648974ba-9c11-4816-9d5e-0623dc4d4d45
- Computers (client) connected over wired or wireless local area network (LAN)
- The database itself and the DBMS are stored on a central device called the database server, which is also connected to the network.
- Distributed Database
collapsed:: true
- Distributed Database #flashcard
id:: 648974ba-b13a-4f3f-8409-ea02b5ef5894
- A logically interrelated collection of shared data (and a description of this data), physically spread over a computer network.
- Distributed DBMS
collapsed:: true
- Distributed DBMS #flashcard
id:: 648974ba-997c-4f43-b2d6-d972cfc23d36
- Software system that permits the management of the distributed database and makes the distribution transparent to users.
- the key issues
collapsed:: true
- the key issues #flashcard
id:: 648974ba-4c63-4215-b420-d537c2a93675
- Fragmentation
- Allocation
- Replication
- importance and different types of fragmentation
collapsed:: true
- importance and different types of fragmentation #flashcard
id:: 648974ba-07aa-4c51-aa70-1c8dfb4570e7
- Horizontal
- Vertical
- Mixed
- different types of transparency
collapsed:: true
- different types of transparency #flashcard
id:: 648974ba-6db5-4d3a-af62-1695e7c3a9b7
- Distribution Transparency: The database feels as a single, logical entity
- Transaction Transparency: Ensures that all distributed transactions maintain distributed database’s integrity and consistency.
- Performance Transparency: must perform as if it were a centralized DBMS.
- advantages and disadvantages of distributed databases
- LATER advantages and disadvantages of distributed databases
- DONE XML
collapsed:: true
- XML definition and basic concepts
collapsed:: true
- LATER XML definition and basic concepts #flashcard
id:: 648974ba-afab-457e-9633-488450e9e16f
- eXtensible Markup Language
- A meta-language (i.e. a language for describing other languages) that
enables designers to create their own customised tags to provide
functionality not available with HTML.
- Relational model versus XML
collapsed:: true
- LATER Relational model versus XML #flashcard
id:: 648974ba-d417-4eef-be28-46cd5894c5c7
- SQL
collapsed:: true
- is a special-purpose programming language
- You can: manage data in a relational databases.
- XML
collapsed:: true
- is a markup specification language
- You can: design ways of describing information (text or data), usually for storage, transmission, or processing by a program (you can use it in combination with a programming language).
- It says nothing about what you should do with the data (although your choice of element names may hint at what they are for).
- Well-formed XML, Valid XML
collapsed:: true
- LATER Well-formed XML, Valid XML #flashcard
id:: 648974ba-fb70-4207-8010-a8ddda35ccf7
- Adheres to basic structural requirements - Single root element
- Matched tags, proper nesting
- Unique attributes within elements
- DTD, XSD
collapsed:: true
- LATER DTD, XSD
- DTD: Defines the valid syntax of an XML document
- XSD: a more comprehensive method of defining content model of
an XML document.
- LATER Practice reading and writing XML, XSD
- DONE Data Mining
collapsed:: true
- concept
collapsed:: true
- concept #flashcard
id:: 648974ba-bf4c-4046-b7ce-510596ad421a
- The process of extracting valid, previously unknown, comprehensible,
and actionable information from large databases and using it to make
crucial business decisions.
- different applications
collapsed:: true
- different applications #flashcard
id:: 648974ba-7440-4ac2-8730-b33e9f50570c
- Retail / Marketing
- Banking
- Insurance
- Medicine
- basic techniques
collapsed:: true
- predictive modelling,
collapsed:: true
- predictive modelling, #flashcard
id:: 648974ba-a007-420c-87db-1a029c1a39e6
- uses observations to form a model of the important characteristics of some
phenomenon
- database segmentation,
collapsed:: true
- database segmentation, #flashcard
id:: 648974ba-18a0-474e-96de-6a824969d0ec
- Uses unsupervised learning to discover homogeneous subpopulations in a database to improve the accuracy of the profiles.
- link analysis,
collapsed:: true
- link analysis, #flashcard
id:: 648974ba-0868-469f-9b8f-94a44163c87f
- Establishing links, called associations, between the individual
records, or sets of records, in a database.
- deviation detection.
collapsed:: true
- deviation detection. #flashcard
id:: 648974ba-a77e-47ba-9f0d-6ed14e880333
- Identifies outliers, which express deviation from some previously
known expectation and norm.
- DONE NoSQL
collapsed:: true
- the motivation for NoSQL
collapsed:: true
- the motivation for NoSQL #flashcard
id:: 648974ba-91af-424f-b392-928e947740de
- By giving up ACID constraints, one can achieve
much higher performance and scalability.
- explain the concepts of NoSQL
collapsed:: true
- explain the concepts of NoSQL #flashcard
id:: 648974ba-370b-44a8-9474-5b58d1d0dd28
- NoSQL databases (aka "not only SQL") are non-tabular databases and store
data differently than relational tables. NoSQL databases come in a
variety of types based on their data model. The main types are document,
key-value, wide-column, and graph. They provide flexible schemas and
scale easily with large amounts of data and high user loads.
- explain the application areas of NoSQL
collapsed:: true
- explain the application areas of NoSQL #flashcard
id:: 648974ba-b39b-47b7-8b9f-ca9250bef8ba
- NoSQL is an alternative, non-traditional DB technology to be
used in large scale environments where (ACID) transactions are not a priority.
- CAP theorem:
collapsed:: true
- CAP theorem: #flashcard
id:: 648974ba-910d-42ae-89a9-5017194f6827
- There are 3 main properties for distributed management:
1. Consistency → A data item has the same value at the same time (to
ensure coherency).