Thank you! The date and time when the record was last modified in the source system. @Triynko Until you bump into 'XyzStatus' table. http://justinsomnia.org/writings/naming_conventions.html. Person, not persons is how you would refer to whoever one of the records represents. The value is extracted from the source (whenever available). Unique identifier of the source system from which data was extracted. You can add additional transaction types to an existing physical table and so reduce the effort of designing and maintaining new physical tables. How to speed up hiding thousands of objects, Doubt in Arnold's "Mathematical Methods of Classical Mechanics", Chapter 2. Big flash in place for this article! If your warehouse is simpler than ours, this may all seem a little over the top. "Fields representing the same kind of data on different tables should be named the same. I would, however, prepend the table name ("PersonID") when its used as a foreign key in other tables. comes in. CRM currency. Conventional Staging Tables. Can I infer that Schrdinger's cat is dead without opening the box, if I wait a thousand years? I have a vague memory from undergrad about a rule that said table names should be pluralized in transactional systems. At times there is a requirement to query facts related to the children of a given parent in the dimension by only specifying the parent value (example: manager's sales fact that includes sales facts of the manager's subordinates). Select * from person where person.name = 'Greg' returns a collection/rowset of person rows. Tables - Documents - Mass Street I think the best answer to each of those questions would be given by you and your team. Contain the metrics being analyzed by dimensions. Currency conversion rate from document currency code to the GLOBAL3 currency code. So you are saying the table is the entity? On the surface, an enterprise data warehouse (EDW) looks almost identical to a databaseboth are accessible via a structured query language (SQL). I dont imagine that this naming convention will work for everyone. Is it persons or people? 1 House, 2 houses, mouse vs mice, person vs people, and we haven't even looked at any other languages. Especially for number 3, we had a agroup of folks who all got hired from the same company and they tried to impose their old naming standard (which none of the rest of us used) on anything they did. ". I'm also in favour of a ISO/IEC 11179 style naming convention, noting they are guidelines rather than being prescriptive. The final remaining step was to kick off a deployment of our entire graph - again in a development environment so that our production data isnt affected - to ensure there were no failures: With that, I created a PR and sent it to one of my colleagues for review. Incorrect names include: Employee, tblEmployee, and EmployeeTable.". It's a COLLECTION. This staging data (list of values translations, computations, currency conversions) is transformed and loaded to the dimension and fact staging tables. There are two types of translation tables: Domain tables that provide multi-language support associated with the values stored in the %_CODE columns. This column identifies the last modified date and time of the auxiliary table's record that acts as a source for the current table. I think its easier to pluralise address, rather than have to rephrase people as person. While a table is also an entity, it is an entity of type "Table" which is pointless to add to its name. There's no possible way that the slight advantage of knowing this is the PK outweighs the incredible annoyance of re-aliasing the dang ID column in every bloody query over and over again. I think both arguments are flawed. A good design pattern for a staged ETL load is an essential part of a properly equipped ETL toolbox. For such logical entities, flags have been provided in the corresponding physical table (for example, W_EMPLOYEE_D) to describe the record's participation in business as different roles. Is there a faster algorithm for max(ctz(x), ctz(y))? However, since most EDWs are columnar, all data is flattened, meaning facts and dimensions are part of the same tables. Use naming conventions for your tasks and components. Staging tables should be used only for interim results and not for permanent storage. It then goes on to provide an example of naming conventions that might be used for relational database. As you say herd to designate a group of sheep, or flock do designate a group of birds. I think we should name plural for Tables and singular for columns. Additionally, tables should be assigned to a schema that identifies the source system of the data. Well, the prefix solution boils down to: These tables arent relevant for analysts, but they are for analytics engineers because the essential compartmentalization also represents the ordinality of the tableseven when theyre hidden from the final consumers of the data. The soft delete feature is disabled by default. This information allows users to drill up and down through the hierarchy in reports. Therefore, when querying the Person star schema on both Accounts and Contacts, every combination of Account and Contact is returned. There are use cases for both compartmentalization on a database or schema-level, and it often has to do with how a company is organized: In an ELT context, when using tools such as dbt orPanoply, the stage of the data object is also relevant. reg_customer, reg_booking and regadmin_limits). But speed isnt the only thing that matters. In this situation, one helper table containing multiple records for each parent-child dimension key combination is inserted between the fact and the dimension. Only use approved acronyms that are expected to be known inside your organization. But yeah Thnkx for spending the time to debate this, I really feel strongly about it and love reading more on this topic. Please excuse my poor English as it is not my first tongue. Thanks for the blog post. Customer Additional Refund? Should 0 be included? I just think that it makes more sense to name objects with accurate plurality. When developing a new project, I'd recommend you write out all the preferred entity names, prefixes and acronyms and give this document to your developers. Staging tables used to hold the metrics being analyzed by dimensions that have not been through the final ETL transformations. 1.3.3.2 About Indices and Naming Conventions. More than once, this has led to him building something from scratch, which we later realised was already covered somewhere else. OBIA object naming convention Table Types Used by the Oracle Business Analytics Warehouse Table Suffix Description Aggregate tables (_A) Contain summed (aggregated) data. I've seen some terrible prefixes, going so far as to state what were dealing with is a table (tbl_) or a user store procedure (usp_). A multi-language support column that holds the name associated with an attribute in all languages supported by the data warehouse. Total = My $0.02 donation to you! Foreign key to the W_USER_D dimension that specifies the user who last modified the record in the source system. I have worked in Data Warehouse before but have not dictated how the data can be received from the source. The currency in which the transaction was done and the related document created. The Plain English Explanation Of What You Are About To Build, Python Software Engineering Considerations, A Methodology To Rapidly Convert OLTP Databases to OLAP Solutions, Business Analytics Capability Maturity Model. Admirable work and much success in your business dealings! For more information about the _DEL table type, see the row for Delete table (_DEL) in this table. This flag is typically critical for Type II slowly changing dimensions, as records in a Type II situation tend to be numerous. This convention could help distinguish between a primary key and foreign keys in the same table. Once again, this can simplify code and allow you to do really neat things, like instantiating a class by having nothing but the table name. Why the inconsistency? One of the main uses of a data warehouse is to sum up fact data with respect to a given dimension, for example, by date or by sales region. Using suffixes instead of prefixes ensures related tables are grouped when ordered alphabetically. Tables that are specially modified to load large amounts of historical data should share the name of the stage table that manages the normal batch process with the addition of the word "Historical" at the end. I have one of my ETL solutions where I used raw files instead of persisted temp table in the database. If you need to have columns like "FirstName", casing will make it easier to read. Why do I get different sorting for the same query on the same data in two identical MariaDB instances? When using a load design with staging tables, the ETL flow looks something more like this: This load design pattern has more steps than the traditional ETL process, but it also brings additional flexibility as well. This document guides ETL developers for the ETLNaming Conventions: PascalCasing (aka Upper Camel Casing) The first character of each word is capitalised. I learned by experience that not doing this way can be very costly in a variety of ways. Keith, on number #3 I do both, and I'm inconsistent (but I digress), but I do not get why it is bad to have a descriptive column name as long as it is not overboard, same with a table, a variable, etc. - Tim Mitchell, Retrieve (extract) the data from its source, which can be a relational database, flat file, or cloud storage, Reshape and cleanse (transform) data as needed to fit into the destination schema and to apply any cleansing or business rules, Insert (load) the transformed data into the destination, which is usually (but not always) a relational database table, Each row to be loaded requires something from one or more other rows in that same set of data (for example, determining order or grouping, or a running total), The source data is used to update (rather than insert into) the destination, The ETL process is an incremental load, but the volume of data is significant enough that doing a row-by-row comparison in the transformation step does not perform well, The data transformation needs require multiple steps, and the output of one transformation step becomes the input of another, Delete existing data in the staging table(s), Load this source data into the staging table(s), Perform relational updates (typically using T-SQL, PL/SQL, or other language specific to your RDBMS) to cleanse or apply business rules to the data, repeating this transformation stage as necessary, Load the transformed data from the staging table(s) into the final destination table(s). I harmonise with your conclusions and will thirstily look forward to your incoming updates. Package Name Convention As the number of packages will grow during the project life, it is suggested to have naming convention for ETL package names so that the package can be manageable. This is a design pattern that I rarely use, but has come in useful on occasion where the shape or grain of the data had to be changed significantly during the load process. Table 4-8 Currency Codes and Rates for Related System Columns. Theyre very focused on user acquisition, but there are at least ten tables that look like they might be relevant: user_stats, user_attribution_stats, users, daily_user_stats, After a brief discussion, we hypothesised that most of our problems could be solved if we structured our data warehouse more clearly and had a clearer naming convention for tables. `select top 15 from order' or 'select top 15 from orders'? This information does not apply to objects in the Oracle Business Intelligence repository. No. Sql will not allow creation of two objects with same name. If so, Id love to hear from you! to prefix columns. It should be legal to beat up someone who does not do this.". The following table summarizes the capitalisation rules for identifiers and provides examples for the different types of identifiers. For our CTO, the issue was with development: they wanted to make some changes to our code, but weren't quite sure where those changes should go. Have you been through a similar process at your organization? Should table names be plural? stores all objects by their uppercase version, by default. Something very similar to this happened to me. Naming is hard but in every organisation there is someone who can name things and in every software team there should be someone who takes responsibility for namings standards and ensures that naming issues like sec_id, sec_value and security_id get resolved early before they get baked into the project. For example, an Opportunity can be associated with many Sales Representatives and a Sales Representative can be associated with many Opportunities. Thats how you make it easy for analysts to find the data assets they need. It all depends on how you think about it. Yes. Currency conversion rate from the document currency code to the local currency code. This topic has generated considerable conflict among analystsfor example. Also, denoting FKs in the names of columns is in my mind another solidly evil anti-pattern. So this persistent staging area can and often does become the only source for historical source system data for the enterprise. I grant that when a new item is needed, it can be added faster. or where you have a M-M relationship between customer_type and customer_category (only certain types are available to certain categories). Does substituting electrons with muons change the atomic shell configuration? No matter how you choose to do it, document it so that future modifications follow the same conventions. SSIS supports both VB.NET & C# Scripts. Tables used to hold information about dimensions that have not been through the final ETL transformations. The Opportunity-Competitor star schema supports a many-to-many relationship between Opportunities and Competitor Accounts, and the Campaign-Opportunity star schema supports a many-to-many relationship between Campaigns and Opportunities. How to use a combination of SQL and Javascript to create an acquisition funnel dataset. Its not suited for quick-write operations, but its excellent for reading data at mind-boggling speed. For example, if a particular star schema requires Buyer as a dimension, the Employee table can be used with a filter where the Buyer flag is set to Y. The second hierarchy, with unstructured parent-child relationships is difficult to model because each child record can potentially be a parent and the number of levels of parent-child relationships is not fixed. That number doesnt get added until the first persistent table is reached. There is a weaker argument to extend this convention to fact tables, however, I do it anyway to satisfy my OCD. Each time you do this, theres a good chance that youll break a link in your dependency graph. Table 4-2 lists the types of tables used in the Oracle Business Analytics Warehouse. These tables are typically tagged as