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Next, sometimes a query might require an SQL index for execution. The memory has to build and maintain this index. If Ignite used a memory mapped files approach, it would be required to read all the data to process the first query. Instead of this, index data is also page based and is stored both in RAM on disk if the latter is enabled.

LetNow let's introduce an integer number -that will define an index of block, page - idx (defined unique within a current node):

idx * blockSize = file offset

Different caches and its partitions brings bring more complex addressation, addressing scheme but still it is still possible to map from page ID to position in particular file

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