Found some interesting things in the source (DiskFile.java):

 * There are 'blocks' of 128 bytes (DiskFile.BLOCK_SIZE). Each objects
own one
 * or more pages; each page size is 64 blocks
(DiskFile.BLOCKS_PER_PAGE). That
 * is 8 KB page size. However pages are not read or written as one
unit; only
 * individual objects (multiple blocks at a time) are read or written.

As I expected, 8 KB page size (which is, I think, kind of usual for a
database system). Maybe the high values for number of I/O operations
are due to the last comment: Only individual objects are read or
written.

This information is extracted by issuing

SELECT * FROM INFORMATION_SCHEMA.SETTINGS WHERE NAME =
'info.FILE_DISK_READ' ORDER BY NAME ASC;

Both before and after any statement is sent to the database. In this
way, I was hoping to count page transfers, but as I can see now, what
I'm probably doing is counting I/O *block* operations.

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