RDD Conversion from Spark-SQL to DataFrame
Case: (bottom)
1. Dynamic programming of metadata to convert RDD into DataFrame - > RDD2 Data Frame Programmatically
2. Reflect RDD-> DataFrame-> RDD2 DataFrame by Reflecting
After RDD is converted to DataFrame, we can use Spark SQL to query any data that can be built into RDD, such as HDFS. This function is extre ...
Posted by webdata on Mon, 06 May 2019 13:45:04 +0200
PostgreSQL Heap Only Tuple - HOT (Reducing Index Writing IO Enlargement Introduced by UPDATE)
Label
PostgreSQL , Heap Only Tuple , HOT
background
PostgreSQL's current default storage engine generates a new version in the heap when updating records. The old version needs to recycle all index POINT associated with this version before it needs to recycle the old version after VACUUM is used.
The KEY of the index of PG is the value of th ...
Posted by Goins on Mon, 06 May 2019 12:45:03 +0200
When configuring relational mapping in 3.2, the table names are different from those in 3.1.
Chapter 3.2 describes the mapping relationship of the corresponding classes according to the steps in the book. It is found that at startup, all the tables previously built in Chapter 3.1 were deleted and re-established, and the data of Ingredient table was lost. Because of the use of JPA, hibernate was used by default, all tables were deleted ...
Posted by axiom82 on Mon, 06 May 2019 04:50:03 +0200
PHP Full Stack Learning Notes 19
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The thinkphp framework is a free, open source, fast and simple object-oriented lightweight PHP development framework.
Learn what is ThinkPHP overview, the directory structure of ThinkPHP projects, the controller of thinkphp, views, the process of building ThinkPHP projects, the configuration of thinkphp, the model o ...
Posted by betazoid on Mon, 06 May 2019 02:50:03 +0200