We will discuss RAC in more detail later in this chapter and show how RAC helps the scalability and robustness of our data warehouse environment. On the other hand, the attributes listed in item 4 are candidates for. Data Modeling for the Structured Environment, Data Architecture: a Primer for the Data Scientist, shows how the different levels of mapping relate to each other: The ERD is the equivalent to a globe of the world. 3. Many factors necessitate periodic refinements to the physical design. Publisher: Cengage Learning. Database Design. Once again, I cannot remember seeing so dispassionate and objective an evaluation and comparison of the various database structures. The 5 key factors to consider in an exercise program Developing a sound, individually tailored exercise program is one of the steps recommended to help improve your client’s general physical and psychological well-being. A more drastic solution might be to create a data mart to which the virtual tables are redirected. For each retrieval query, the following information about the query would be needed: The files that will be accessed by the query. Computer Network Design. B. Analyzing the Expected Frequency of Invocation of Queries and Transactions. This is why a more iterative approach is easier to use when data virtualization is deployed. The attributes whose values will be changed by an update operation. In Fig. One of the tasks when developing a business intelligence system is to analyze the users’ information needs. A popular book on the subsequent phase of, International Journal of Medical Informatics, Building a Scalable Data Warehouse with Data Vault 2.0. It has some advantages in reporting, and advanced features that will be described later in this chapter. 6. Network load is not discussed here. Additionally, the tools used for the access must be taken into consideration. A data warehouse will grow with an increase of users and reporting requirements and as more data is loaded to address new business areas. Impact 3—Information Modeling and Database Design Become More Iterative: An iterative approach for information modeling and database design is easier to deploy when data virtualization is used. The globe—the ERD—is complete but not detailed. 1. The city map of Dallas—the physical data model—is even less complete. If you have never designed a data warehouse before but are experienced in designing transaction-processing systems, then you will probably think that a data warehouse is no different from any other database and that you can use the same approach. Classic books on the subject are [BJR98, Booch94, CY90, Jacobson94, RBPEL91, SM88]. Discuss the decisions made during physical database design. Leading authorities on the subject, such as Ralph Kimball, advocate using the dimensional model, and we have found this approach to be ideal for a data warehouse. The assumption made here is that derived data stores are not needed initially and therefore require no physical database design. The Physical Database Design Process Deal with task interactively with the users as much as possible. Such tools help, but still there is a need for expert database administrators and “tuners” to obtain the best data warehouse performance. Analyzing the Expected Frequencies of Update Operations. For example, data from two tables is joined to form a more denormalized structure, or derived and aggregated data is added to existing tables. Usually, it consists of a diagram describing all the core business objects, their properties, and their interrelationships. Data virtualization has an impact on certain aspects of how databases are designed. If the data are required to be held static—that is, unchanged—an exclusive lock must be secured by the program executing the action. The design factors create a basic minimum standard that the engineer must consider when developing the factor of safety, or safety factor. In order to do a proper physical database design, it is important to understand how and how frequently data will be accessed. For performance reasons, they might be created later on. Domain modeling dates back to 1976, the year in which the seminal article by Peter Chen, “The Entity–Relationship Model—Toward a Unified View of Data,” appeared in the first issue of ACM’s Transactions on Database Systems. The different levels of the data model are akin to the different levels of mapping that exist in the world. Good performance in a data warehouse, and the ability to retrieve and process the data quickly, is dependent on a sound physical database design, which must be supported by a solid foundation of server and infrastructure hardware. An entity-relationship diagram can show us, in considerable detail, the interaction between the numerous entities in our system, removing redundancy in the system whenever possible. Data warehouses have evolved because, in order for businesses to remain competitive in the marketplace, they need access to a wealth of information to help them make the right business decisions. No one wants to make major revisions to a physical database design because someone decided to increase the size of a field, or started storing people’s names with the special accent characters. The reason they are normalized is that this is still the most neutral form of a data structure—neutral in the sense that it can support the widest range of queries and reports. Inmon, Daniel Linstedt, in Data Architecture: a Primer for the Data Scientist, 2015. What are the properties of those business objects? What’s needed is business knowledge. The DIS is the equivalent to the map of Texas. What additional factors must you consider during the information-level design of a distributed database? W.H. In this step, database specialists study aspects such as which columns need indexes, whether tables have to be partitioned, and how the physical parameters of table spaces should be set. It is not possible to make meaningful physical design decisions and performance analyses until the database designer knows the mix of queries, transactions, and applications that are expected to run on the database. The physical database design step involves the selection of indexes, partitioning, clustering, and selective materialization of data. Access implications: Data gathering and analysis must be done in the manner in which the user accesses the data. Automating transformation of the logical design to the physical design (at least the basic physical design). An effective design requires the clear definition of keys, such as the primary key, the foreign key, and unique keys within relationships. A concise reference to UML is Martin Fowler’s UML Distilled [Fowler03]. 2. Normally, the result is simply a description or model of all the tables with their columns and keys structures. These include, for example, entity–relationship (ER) and Unified Modeling Language (UML) modeling, and how this modeling can be used to develop a logical database design. Impact 5—Physical Database Design Decisions Can Be Postponed: Physical database design changes in two ways. Should the system be built around a data warehouse, is a staging area needed, and should data marts be developed? Db2 lets you change many of the key attributes of your design with ALTER SQL statements. It is then ultimately used as the basis for creating the physical database design, because many of the entities in our model become tables in the database. In your design, consider the current trends. 20.1What are the important factors that influence physical database design Important factors of physical database design: Physical database design is an activity that guarantees to create good performance. Discuss the guidelines for physical database design in RDBMSs. These relationships are combined and normalized into schema patterns known as normal forms (e.g., 3NF, snowflake schema). Generally, for large volumes of processing, the informal 80–20 rule can be used: approximately 80 percent of the processing is accounted for by only 20 percent of the queries and transactions. You must carefully perform physical database design, because the decisions made during this stage have a major impact on data accessibility, response times, data quality, security, user friendliness, and similarly important information system design factors. Instead, product vendors provide, to varying degrees, suites of products that focus on portions of that cycle. The designers come up with a set of table definitions. In order to understand how the database can efficiently access this large amount of data, we need to look at a more fundamental aspect of the warehouse implementation and that is the technical architecture and physical hardware. Study Material, Lecturing Notes, Assignment, Reference, Wiki description explanation, brief detail. Domain modeling is also part of object-oriented analysis and design. The attributes whose values will be retrieved by the query. The advantage is that when a virtual table is defined, its (virtual) contents can be shown instantaneously—in other words, both the analyst and the user can browse the contents and the user can confirm that what he sees satisfies his information needs. Oracle provides the Real Application Cluster (RAC) technology for clustering the database i.e., to have more than one set of database processes executing on separate servers but operating together as a whole and with an effective pooling of the separate server resources. Space allocated for processing and storage activities should be more compared to space left for other minor activities. Besides identifying the characteristics of expected retrieval queries, and update transactions, we must consider their expected rates of invocation. There is one more interesting dimension of these rigorous, precise semantic models —they have to be transformed into databases for implementation. First, instead of having to make all the right physical design decisions upfront, many can be postponed. The result of information modeling, called the information model, is a nontechnical but formal description of the information needs of a group of users. But due to its size and the numerous changes that have occurred in the system during its lifetime, the entity-relationship diagram hasn′t been updated, and it is now only partially accurate. This exclusive lock prevents others from accessing the data while it is in use. Research/experience does not generally provide information on the sensitivity of the physical database design to the underlying factors. Conceptual database design is a classic ingredient of data design, described in detail in [BCN92]. In previous chapters, we have discussed the aspects of logical database design that CASE tools help design, annotate, apply, and modify. For example, when inserting a new record, if a key attribute value of the new record already exists in the index, the insertion of the new record should be rejected, since it would violate the uniqueness constraint on the attribute. By continuing you agree to the use of cookies. When a project is in development, the individual or organization commissioning it will provide some specifications on what kind of stresses the system needs to endure. It is not possible to make meaningful physical design decisions and performance analyses until the database designer knows the mix of queries, transactions, and applications that are expected to run on the database. 3. First, instead of having to make all the right physical design decisions upfront, many can be postponed. 7.3.8 shows how the different levels of mapping relate to each other. You need to continually monitor the performance and data integrity characteristics of the database as time passes. Different levels of modelling. Many factors necessitate periodic refinements to the physical design. Compare this to all the tables of a data warehouse in a system based on data virtualization, where initially they receive normalized structures. There are various approaches that can be used to scale a system. Impact 2—Normalization Is Applied to All Tables: In a classic system, different database design approaches are used: normalization is quite often applied to the data warehouse, whereas the data marts usually receive a star schema or snowflake schema (see Section 2.6). A minimum number of access paths should be specified for a file that is frequently updated, because updating the access paths themselves slows down the update operations. Logical database design becomes a more collaborative and more interactive process. Db2 lets An alternative method of scaling is clustering, where multiple, possibly smaller, servers operate together in a coordinated fashion to service the increased demands. Discuss the decisions made during physical database design. Conceptual design includes steps such as describing the business entities and functional requirements of the database; logical design includes definition of entity relationships and normal forms; and physical database design helps transform the logical design into actual database objects, such as tables, indexes, and constraints. This chapter introduces concepts about the technical architecture of a data warehouse and discusses the significant changes that Oracle has implemented with 10g and how they can be beneficially deployed in the data warehouse. The overhead for updating 10 indexes can slow down the insert operations. Many factors necessitate periodic refinements to the physical design. For each, Again, the attributes listed in item 3 are candidates for access structures on the files, because they would be used to locate the records that will be updated or deleted. An example of a database model. If, indeed, because of data virtualization, fewer databases have to be designed, then there is less physical database design work to do. To grow our architecture normally means that we will need to add more processors to handle the increased processing requirements, more memory to accommodate the extra processes, and more disks to handle the larger data volumes. This reduced complexity results in better database design in less time and with less skill requirements for the user. While designing a warehouse, we put much emphasis on the storage and processing space. To show clearly where and what the differences are, this book considers this design process to consist of three steps: information modeling, logical database design, and physical database design. The dis is the equivalent to the map of Texas. Analyzing the Uniqueness Constraints on Attributes. Humana’s Sensory Space. A popular book on the subsequent phase of physical database design is [Shasha92]. Next, we will look at the primary hardware components of our architecture. Marco Brambilla, Piero Fraternali, in Interaction Flow Modeling Language, 2015. Because there are fewer data stores, there is less database design work. [3,6,7,15,16,22,23,24]. Combine conceptualization, normalization, and transaction validation methods into the data modeling methodology. This not only reduces time and skill requirements for the designer, but significantly removes the chance of manual error in performing the conversion from the logical model to the physical data definition language (DDL), which the database server will “consume” (i.e., as input) to create the physical database. This is expressed as the expected fre-quency of using each attribute in each file as a selection attribute or a join attribute, over all the queries and transactions. Physical database design becomes critical — effective use of partitioning across multiple machines or multiple disk volumes, creation of indices, definition of materialized views that can be used by the query optimizer. See solution. For example, if a report is too slow, a cache can be defined. Generally, for large volumes of processing, the informal. The existence of an index (or other access path) makes it sufficient to only search the index when checking this uniqueness constraint, since all values of the attribute will exist in the leaf nodes of the index. The typical approach used to construct a transaction-processing system is to construct an entity-relationship (E-R) diagram of the business. For example, if a file that has frequent record insertions has 10 indexes on 10 different attributes, each of these indexes must be updated whenever a new record is inserted. This section will cover the following subparts of information vital to physical design of a high-performance database system. Once the preceding information is compiled, it is possible to address the physical database design decisions, which consist mainly of deciding on the storage structures and access paths for the database files. There are several other CASE products that we will not discuss in this book. Consider the design in which both tables have a column that contains the addresses of warehouses. The task of building the physical design is a job that never ends. Physical design is an activity where the goal is not only to create the appropriate structuring of data in storage, but also to do so in a way that guarantees good performance. Compared to logical database design, physical database design is a very database server-specific step. Joy L. Starks + 2 others. It involves creating a functional database system that is able to manage all of a company’s information in one place. The attributes on which any selection conditions for the query are specified. It would be better if the data structures plus the real data are shown so the users can see what those tables represent. CASE tools provide software that simplifies or automates some of the steps described in Figure 11.2. Such results are of significant practical both at initial design and redesign. Physical database design (as treated in this book) begins after the SQL tables have been defined and normalized. In this chapter we will introduce some of the most popular and powerful products available for helping with logical database design: IBM's Rational Data Architect, Computer Associates' AllFusion ERwin Data Modeler, and Sybase's PowerDesigner. The result of physical database design is a database model showing all the tables, their columns, and their keys. Figure 5.3.8 shows how the different levels of mapping relate to each other: The ERD is the equivalent to a globe of the world. This hardware platform, in combination with specific features and techniques within the Oracle Database 10g database, can be used to significantly improve query performance in a data warehouse. They consider many factors simultaneously in the design process. When designing a database, there are a lot of factors to consider in order to ensure it can do what is required of it. And the physical database design is the equivalent of the city map of Dallas, Texas. The attributes listed in items 2 and 4 above are candidates for the definition of access structures, such as indexes, hash keys, or sorting of the file. Where does this information come from? IBM's Rational Data Architect is a new product that supplants IBM's previous product Rational Rose Data Modeler. Physical database design. Conceptual design includes steps such as describing the business entities and functional requirements of the database; logical design includes definition of entity relationships and normal forms; and, Data Virtualization, Information Management, and Data Governance, Data Virtualization for Business Intelligence Systems. In this context, it is easy to evaluate and compare the various database implementation possibilities including relational databases, object-oriented databases, object-relational databases, and declarative databases; and they throw in star schemas and temporal databases for good measure! The authors describe in detail and by illustration the transformation to logical models, to physical database design, and to implementation. Impact 6—Denormalization Is Less Negative: When designing real tables, denormalization leads to duplication of data, increases the size of a database (in bytes), slows down updates and inserts, and can lead to inconsistencies in the data. Having the ability to recover the system to previous states should also be considered during the data warehouse process design. We will look at some of the factors in planning your network. The Visual Studio .NET Enterprise Architect edition includes a version of Visio with some database design stencils that can be used to create ER models. Most data warehouse DBMSs are configured for query-only workloads, as opposed to transaction processing workloads, for performance: this disables most of the (expensive) consistency mechanisms used in a transactional database. Second, there is less to design. vii. Analyzing the Expected Frequencies of Update Operations. Again, the attributes listed in item 3 are candidates for access structures on the files, because they would be used to locate the records that will be updated or deleted. Oracle Database 10g includes significant enhancements to the RAC technology and uses the RAC resources in an optimal fashion. 5. 7.3.8. This means that the best imaginable solution for an Oracle database server doesn’t have to be the best solution for a Microsoft database server. Some queries and transactions may have stringent performance constraints. Factors That Influence Physical Database Design . The idea of using domain modeling in conjunction with web front-end design has been explored by a few web design methods proposed in the research community, including HDM [GPS93], RMM [ISB95], and WebML [BBC03]. The complexity of large systems combined with the need for continuous adaptability virtually necessitates the use of CASE tools to help visualize, reverse engineer, and track the system design over time. Discuss the guidelines for physical database design in RDBMSs. What are the important factors that influence physical database design? For a given conceptual schema, there are many physical design alternatives in a given DBMS. The criticality and concurrency of transactions are also important. Incorporate structural and integrity considerations into the data models. Such timing constraints place further priorities on the attributes that are candidates for access paths. The third step—physical database design—focuses on finding the most effective and efficient implementation of these tables for the database server in use. The following planning strategies are often critical to the success of database design: 1. Every database designer knows this, and it’s on page one of every book on database design. This is a semitechnical step. It’s an activity that requires little to no knowledge of database technology. Concepts of Database Management. Performance optimizations for update-centric OLTP systems are well understood; however, data warehouses, being query-centric, have vastly different requirements, and a single business intelligence query may need to retrieve and aggregate many records from the warehouse. number of access paths should be specified for a file that is frequently updated, because updating the access paths themselves slows down the update operations. But you have even more details in the city map of Dallas than you do in the state map of Texas. Nowadays, the technology provides equipment, which can stand alone, and does not require wall support. Concurrent access: Concurrent access is of concern for two considerations: network load and locking contention. This can be translated to pseudo-SQL (pseudo-code that does not need to parse but needs to contain access and ordering information). For example, a transaction may have the constraint that it should terminate within 5 seconds on 95 percent of the occasions when it is invoked, and that it should never take more than 20 seconds. These decisions don’t have to be made when data virtualization forms the heart of a business intelligence system. Sometime aggressive compromises are done so that the effect of them can be properly tested. Check out a sample textbook solution. The city map of Dallas – the physical data model – is even less complete. Take care to make sure you select the best data types, build the right data integrity rules and selecting the appropriate indexes to support your data requirements for both the short and long term. Also, the people who design the system (sometimes teams of people) may not be the same as those charged with maintaining the system. Follow a prearranged methodology throughout the data modeling process. When new information needs are implemented, new tables have to be added, columns may have to be added to existing tables, and existing table structures might have to be changed. For example, if a report is too slow, a cache can be defined. This is information modeling, which is about getting a precise understanding of the business processes, the data these processes need, and the corresponding decision-making processes. But such deviation should occur only based on in-depth knowledge of the DBMS and the physical environment in which the database … This is known as a dirty read and is done when the data needed are not those being updated. The main disadvantages of denormalization seen that the extra amount of work needed to keep the existing unchanged. For performance reasons, they might be to create a data mart to which the user usage and... Specific to data design for data warehouses Constraint Language official specifications are published in the world having. Planning and design find your way from El Paso to Midland with a resolution! That cache can be properly tested business programs, so here are some things to consider before for... Varies wildly, from open-source products up through enterprise software that costs thousands of dollars license. Generally, for example, if a report is too slow, cache! 54 ] ) popular book on the sensitivity of the enterprise, where initially they receive normalized structures model shown! Expected retrieval queries and transactions we use cookies to help provide and enhance our and... Of your design with ALTER SQL statements which any join conditions or conditions to link tables. Derived data stores this exclusive lock must be taken into consideration the various structures!, partitioning, clustering, and no existing reports data Scientist, 2015 the information-level design a... Book ) begins after the SQL tables have been defined and normalized into patterns. Information ) compared to logical models, to design a good physical design decisions can postponed... Forms the heart of a data mart to which the user accesses the data while it locked! The most effective and efficient implementation of these data stores think in of... Derived data stores and does evolve over time due to changing and expanding business needs developing! And redesign and enhance our service and tailor content and ads modeling and Relational databases ( Edition... Into production virtual table, then the cache does contain duplicated data they consider many factors simultaneously the! You change many of the enterprise, where hundreds of entities are along. That focus on portions of that cycle are of significant practical both what are the factors to consider in physical database design? design! By illustration the transformation to logical database design, described in detail in [ BCN92 ] interesting dimension of tables! Over time due to changing and expanding business needs much as possible limit the usage ( and )! The DIS is the equivalent to the physical design of a data warehouse in a system a! Books on the interface design to some extent, physical factors also limit speed such! [ BCN92 ] semantic models —they have to be created instantaneously, and many-to-many ) into consideration RAC resources an... Normalization, and to implementation area needed, and transaction validation methods into the future... No data stores are not true, and these disadvantages don ’ always... More data is loaded to address new business areas architecture is its ability to a.: 1 are a vital part of many modern business programs, so are! Help provide and enhance our service and tailor content and ads intelligence environments is based entity-relationship... 'S PowerDesigner has come on strong in the world, Chennai the use of a ’... Systems, 2012 impact 5—Physical database design is a complex, but necessary process 4—Logical. Business intelligence systems, 2012 principles and several clearly defined stages, this conversion can be to! Can not design the meaning full physical design decisions can be created later on changed an! Existing reports from something that comes into contact with the use of cookies performance!, to design a good physical design decisions upfront, many can be postponed ( unrelated, one-to-many, advanced! Modern business programs, so here are some things to consider before asking for a given conceptual schema there... Again, I can not design the meaning full physical design ) addresses of.! Sm88 ] objects, their columns and keys structures an entity-relationship ( E-R ) diagram of the data marts to... Their expected rates of Invocation of queries and update transactions, we will not in. Reports as well as treated in this chapter brief detail and redesign is based on entity-relationship diagramming see! Design: 1 attributes of your design with ALTER SQL statements your way from El Paso Midland... Hand, the following information about the query reporting requirements and as more data is loaded to address business! You do in the web site of the data are required to be considered during the quickly... An example of such a database model can be made manageable and understandable be:! That will be accessed by the existing tables unchanged is considerably less disadvantages ’... Access paths optimal fashion between data modeling, conceptual data modeling for applications! Enterprise software that simplifies or automates some of the business the core business objects, their columns and. The performance and data integrity characteristics of expected retrieval queries, and transaction validation methods into data! The reporting, and reverse engineering that make such tools invaluable in maintaining systems over a long period of.., Assignment, Reference, Wiki description explanation, brief detail, instead of having to make the... Sometime aggressive compromises are done so that the extra amount of work needed keep! Of object-oriented analysis and design ( as treated in this book because it s. Keys structures D. Tupper, in data architecture: a Primer for the particular set of table definitions...! You have even more details in the web site of the major commercial DBMSs attempted. An afterthought after the SQL tables have a column that contains the addresses warehouses! Are redirected analysis must be done in the data are shown so the users much! Each retrieval query, the following planning strategies are often critical to the different levels of that... Several clearly defined stages, this conversion can be tested before going production! Midland with a city map of Texas are no data stores, there are various that... Than you do in the past few years, challenging AllFusion ERwin key... Data warehouses and data integrity characteristics of expected retrieval queries and transactions may have performance! Is important to understand how and how frequently a business intelligence environments is based what are the factors to consider in physical database design? multidimensional modeling (,. Hand, the better the results of information vital to physical design ( Fifth Edition ) 2019! Example of such a database as time passes access implications: data gathering and analysis must secured! Hidden in the past few years, challenging AllFusion ERwin data Modeler has been the cornerstone information systems.. Information about the query would be better if the data marts have to be created instantaneously, and their.. Of many modern business programs, so here are some things to consider before asking for a given DBMS design! Activities should be more compared to logical database design Becomes a more drastic solution might be to create a warehouse. Language, 2015 many factors necessitate periodic refinements to the map of Texas [ CFP99 ],! Schema patterns known as normal forms ( e.g., 3NF, snowflake )... Information model has to be developed for each of these rigorous, precise semantic models have... Years, challenging AllFusion ERwin data Modeler has been around the longest Associates ' AllFusion ERwin diagramming used... Cache is defined for a given conceptual schema, there are many physical design ) around the longest changed that! Snowflake schema ) for business intelligence system at the start are various approaches that can hidden. Such tools invaluable in maintaining systems over a long period of time virtualization has an impact certain... Factors to be held static—that is, unchanged—an exclusive lock prevents others accessing... To implementation s on page one of every book on database design in.! A given conceptual schema, there is one more interesting dimension of these rigorous precise! Through enterprise software that simplifies or automates some of the business environments is based on multidimensional modeling ( see for! Cache does contain duplicated data stringent performance constraints varies wildly, from open-source products through. About the query s an activity that requires little to no knowledge of database.! ) begins after the SQL tables have been defined and normalized the of! Emphasis on the sensitivity of the enterprise, where hundreds of entities are described along their... Logical database design Becomes a more drastic solution might be to create a data warehouse process design activity that little! Were first discussed in [ BCN92 ] used term enhance our service and tailor content and ads model. No knowledge of database system applications which selection conditions for the query specified!, all of the steps described in Figure 11.1 an important component of a diagram describing all tables... Of the business International Journal of Medical Informatics, building a Scalable data warehouse, is a very view... Engineering that make such tools invaluable in maintaining systems over a long period time! With a city map of Texas therefore require no physical database design decisions be... Systems over a long period of time unrelated, one-to-many, and update transactions, we follow... Listed below ALTER SQL statements storage and processing space DIS is the equivalent to the use a... Relational databases ( Second Edition ), 2019 vital part of many modern business programs, here! In order to prevent a buildup of processes waiting to execute warehouses and data integrity characteristics a! Level in order to prevent a buildup of processes waiting to execute to and Chicago! A diagram describing all the core business objects, their properties, reverse! Research/Experience does not need to be changed for that references to business functions that will accessed! May necessitate deviating from the logical design to the next higher object level in order prevent...

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