Database query method and server

Abstract

The embodiment of the invention provides a method for querying a column type internal memory database. The method comprises the steps of receiving a query request, analyzing the query request, acquiring a query condition, determining a target column related to the query condition from the column type internal memory database, executing the following steps in a cycled mode until query of all rows is achieved, storing data queried in the continuous m rows in all the target columns or the data less than m rows at last into a Cache from the column type internal memory database starting from the [m*(i-1)+1]th row of each target column, querying the data stored in the Cache according to the query condition, sending sectionalized query results, and releasing the storage space of the Cache, wherein the m is a natural constant, and the i is a variable and represents the cycled executing frequency. The method is used, so that data flooding in the query process is lowered, and time delay of data query is reduced.

Description

technical field [0001] The embodiment of the present invention relates to database technology, in particular to a database query method and server. Background technique [0002] Cache is a temporary storage located between the CPU and the memory RAM. Its capacity is smaller than that of the memory but the exchange speed is faster. When the CPU calls a large amount of data, it can be called directly from the Cache, thus speeding up the reading speed. Usually, the Cache is divided into L1, L2, and L3 levels. L1 is the space exclusively used by a single core of a single CPU, L2 is the space shared by multiple cores of a single CPU, and L3 is the space shared by multiple CPUs and multiple cores, for example : The cache sizes of L1, L2, and L3 are 32K, 512K, and 15360K, respectively. Taking each read of 256Byte as an example, the delays of the three caches are: 1.2ns, 4ns and 30ns. And it takes 100ns to read data in memory RAM. In the case of the same instruction, the data is...

AI Technical Summary

Problems solved by technology

If the intermediate data is further calculated later, these intermediate data need to be taken out from RAM and calculated, then the process of reading data from RAM will cause a large delay, and if the calculation becomes complicated, the delay will increase exponentially

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