Data Warehouse of Horrors: 20 Years of Watching Smart People Build Stupid Things

There was a time when a single team could build an entire data warehouse. Not a team of forty. Not a team of sixty distributed across three continents and coordinated by a project management office that had never seen an execution plan. A team of five. Perhaps six, if one counts the person from Controlling …

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Layer and Preparatory Table Strategies

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Typically, query tuning involves altering the composition of various objects. An alternative method for achieving quicker results, in cases where modifying SQL, is not feasible or has already been completed, involves substituting the objects from which data is retrieved. By incorporating intermediate objects into a daily job chain, numerous queries can be expedited, resulting in …

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Real-World Map-Reduce Implementations: Design and Fault Tolerance

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Here is an illustration depicting the design of real-world map-reduce implementations, such as Hadoop: The input files reside in a distributed file system, such as HDFS for Hadoop, or GFS as Google calls it. Worker processes handle mapper or reducer tasks. Mappers read data from HDFS, apply the mapping function, and save the output to …

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Understanding Teradata Load Isolation

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Isolation Levels and their Impact on Performance & Concurrency Isolation is a crucial factor in determining the visibility of transaction integrity to database users. This property guarantees that concurrently executed transactions produce identical results to those executed sequentially. Nonetheless, relinquishing this requirement can enhance transaction concurrency, improving performance. However, this also implies accepting inconsistent outcomes. …

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Building a Teradata Data Warehouse: Considerations for ETL Process, SQL Queries, and Physical Data Model

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This post aims to compile all crucial aspects to be considered while constructing a Teradata Data Warehouse, including the ETL process and SQL queries. This list is just the beginning, and I anticipate receiving valuable feedback from my readers to expand it in the future. Initially, I have provided a few concepts, but I intend …

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Understanding the Waterfall Model: Phases, Problems, and Solutions for Data Warehouse Projects

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What is the Waterfall Model? The waterfall model facilitates the sequential progression of a data warehouse project. Each phase must be concluded before the subsequent stage commences. The following stages will be navigated: What are the Problems with the Waterfall Model? Typically, these issues are identified solely during the verification stage of testing. Why do …

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Teradata Referential Integrity: What it is and Why You Need it for Data Consistency and Performance

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Introduction to Teradata Referential Integrity Teradata implements 3 Types of Referential Integrity. 1. What is Standard Referential Integrity? The Standard Referential Integrity checks every Row INSERT, DELETE, or UPDATE immediately to ensure referential integrity. A reference index sub-table is required for referential integrity. Violation of referential integrity results in the failure of execution and generates …

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7 Deadly Sins That Destroy A Teradata Data Warehouse

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To exemplify the impact of mistakes in Teradata Data Warehouse projects, consider the analogy of a medical team. Imagine yourself as the project, preparing for a crucial and costly procedure. Naturally, you wouldn’t want to hear the staff engage in the following conversations before administering the anesthesia. 1. Not knowing or losing Sight of the …

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The Importance of Teradata Surrogate Keys

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What are Teradata Surrogate Keys? A Teradata Surrogate Key is an artificial key that maps to a natural key. It is usually of the data type INTEGER or BIGINT and is represented by a single column. The natural key can consist of multiple columns. The surrogate key is generated automatically and is represented by an …

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