单例模式是一种创建型设计模式， 它的核心思想是保证一个类只有一个实例，并提供一个全局访问点来访问这个实例。 只有一个实例的意思是，在整个应用程序中，只存在该类的一个实例对象，而不是创建多个相同类型的对象。 全局访问点的意思是，为了让 ...

SPI_getvalue returns the string representation of the value of the specified column. The result is returned in memory allocated using palloc. (You can use pfree to release the memory when you don't ...

Function from an allocation entry object to anything. The table will group and aggregate entries by their keys. Defaults to the stack at the time of the allocation. getValue: Optional. Function from ...

This section contains a very simple example of SPI usage. The C function execq takes an SQL command as its first argument and a row count as its second, executes the command using SPI_exec and returns ...