G
gus
Guest
More: Suppose you have maximum-rows-per-block at 256 and 8k data blocks. Now you put a single 100 byte record into a block. It will look like this: Block size 8192 bytes Data Block header 64 bytes Record block extra header 12 bytes Row directory for 1 record 2 bytes Per row overhead (17 x 1) 17 bytes Create limit 300 bytes Total overhead 395 bytes Space left for records 7797 bytes 1 100 byte record 100 bytes Free space 7697 bytes. Note that the row directory is only /one/ slot at this point. If we put another 100 byte record into the same block, we expand the row directory by one more entry (2 bytes) and we add another 17 bytes of overhead for the second record. So the second record uses 119 bytes of space (100 + 2 + 17). We end up with this: Block size 8192 bytes Data Block header 64 bytes Record block extra header 12 bytes Row directory for 1 record 4 bytes Per row overhead (17 x 2) 34 bytes Create limit 300 bytes Total overhead 414 bytes Space left for records 7778 bytes 2 100 byte records 200 bytes Free space 7578 bytes.
Continue reading...
Continue reading...