Re: [HACKERS] Misunderstanding on the FSM README file
2014-12-07 15:07 GMT+01:00 Heikki Linnakangas hlinnakan...@vmware.com: On 12/07/2014 02:03 PM, Guillaume Lelarge wrote: Hi, I've been reading the FSM README file lately (src/backend/storage/freespace/README), and I'm puzzled by one of the graph (the binary tree structure of an FSM file). Here it is: 4 4 2 3 4 0 2- This level represents heap pages Shouldn't the last line be: 4 3 2 0 (ie, highest number of free space on the left node, lowest on the right one) Probably just nitpicking, but still, I'm wondering if I missed something out. No, that's not how it works. Each number at the bottom level corresponds to a particular heap page. The first number would be heap page #0 (which has 3 units of free space), the second heap page #1 (with 4 units of free space) and so forth. Each node on the upper levels stores the maximum of its two children. Oh OK. Thanks Heikki, that makes perfect sense. -- Guillaume. http://blog.guillaume.lelarge.info http://www.dalibo.com
Re: [HACKERS] Misunderstanding on the FSM README file
On 12/07/2014 02:03 PM, Guillaume Lelarge wrote: Hi, I've been reading the FSM README file lately (src/backend/storage/freespace/README), and I'm puzzled by one of the graph (the binary tree structure of an FSM file). Here it is: 4 4 2 3 4 0 2- This level represents heap pages Shouldn't the last line be: 4 3 2 0 (ie, highest number of free space on the left node, lowest on the right one) Probably just nitpicking, but still, I'm wondering if I missed something out. No, that's not how it works. Each number at the bottom level corresponds to a particular heap page. The first number would be heap page #0 (which has 3 units of free space), the second heap page #1 (with 4 units of free space) and so forth. Each node on the upper levels stores the maximum of its two children. - Heikki -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
