Tag: wide table

Wide table abounds in BI business. Whenever building a BI system, the first thing you need to do is to prepare a wide table. Sometimes the wide table in the system may have hundreds of fields, splitting this table is often needed due to “too wide” exceeding the limit on the number of fields of database table. Why are people so keen on creating wide table? There are two main reasons. One is to improve query performance. Usually, modern BI takes relational database as backend, yet the computing performance of HASH JOIN algorithm that SQL usually adopts will decrease sharply