Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-04-26 Thread Bruce Momjian
Patch applied. Thanks. --- Mark Kirkwood wrote: > Mark Kirkwood wrote: > > Tom Lane wrote: > > > >> > >> I do notice a rather serious shortcoming of pg_freespacemap in its > >> current incarnation, which is that it *only*

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-19 Thread Mark Kirkwood
Mark Kirkwood wrote: Tom Lane wrote: I do notice a rather serious shortcoming of pg_freespacemap in its current incarnation, which is that it *only* shows you the per-page free space data, and not any of the information that would let you determine what the FSM is doing to filter the raw data.

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-13 Thread Alvaro Herrera
Mark Kirkwood wrote: > Christopher Kings-Lynne wrote: > >>The point here is that if tuples require 50 bytes, and there are 20 > >>bytes free on a page, pgstattuple counts 20 free bytes while FSM > >>ignores the page. Recording that space in the FSM will not improve > >>matters, it'll just risk pus

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Mark Kirkwood
Christopher Kings-Lynne wrote: The point here is that if tuples require 50 bytes, and there are 20 bytes free on a page, pgstattuple counts 20 free bytes while FSM ignores the page. Recording that space in the FSM will not improve matters, it'll just risk pushing out FSM records for pages that d

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Christopher Kings-Lynne
The point here is that if tuples require 50 bytes, and there are 20 bytes free on a page, pgstattuple counts 20 free bytes while FSM ignores the page. Recording that space in the FSM will not improve matters, it'll just risk pushing out FSM records for pages that do have useful amounts of free sp

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Tom Lane
Tatsuo Ishii <[EMAIL PROTECTED]> writes: > That sounds strange to me. Each record of accounts tables is actually > exactly same, i.e fixed size. So it should be possible that UPDATE > reuses any free spaces made by previous UPDATE. If FSM neglects those > free spaces "because they are uselessly sma

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Tatsuo Ishii
> > Tatsuo Ishii wrote: > >> BTW, I noticed difference of outputs from pg_freespacemap and > >> pgstattuple. > >> > >> I ran pgbench and inspected "accounts" table by using these tools. > >> > >> pg_freespacemap: > >> sum of bytes: 250712 > >> > >> pgstattuple: > >> free_space: 354880 > >> > >>

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Mark Kirkwood
Tom Lane wrote: Tatsuo Ishii wrote: BTW, I noticed difference of outputs from pg_freespacemap and pgstattuple. I ran pgbench and inspected "accounts" table by using these tools. pg_freespacemap: sum of bytes: 250712 pgstattuple: free_space: 354880 Shouldn't they be identical? vacuum/fsm

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Tom Lane
> Tatsuo Ishii wrote: >> BTW, I noticed difference of outputs from pg_freespacemap and >> pgstattuple. >> >> I ran pgbench and inspected "accounts" table by using these tools. >> >> pg_freespacemap: >> sum of bytes: 250712 >> >> pgstattuple: >> free_space: 354880 >> >> Shouldn't they be identic

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-12 Thread Mark Kirkwood
Tatsuo Ishii wrote: BTW, I noticed difference of outputs from pg_freespacemap and pgstattuple. I ran pgbench and inspected "accounts" table by using these tools. pg_freespacemap: sum of bytes: 250712 pgstattuple: free_space: 354880 Shouldn't they be identical? I would have t

Re: [PATCHES] [HACKERS] pg_freespacemap question

2006-03-11 Thread Tatsuo Ishii
BTW, I noticed difference of outputs from pg_freespacemap and pgstattuple. I ran pgbench and inspected "accounts" table by using these tools. pg_freespacemap: sum of bytes: 250712 pgstattuple: free_space: 354880 Shouldn't they be identical? -- Tatsuo Ishii SRA OSS, Inc. Japan -