Thread
Commits
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Avoid creating a TOAST table for a partitioned table.
- 2fe6336e2d48 11.0 landed
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TOAST table created for partitioned tables
Amit Langote <langote_amit_f8@lab.ntt.co.jp> — 2018-01-16T10:13:41Z
Hi. I used to think that $subject didn't happen, but it actually does and ends up consuming a fixed 8192 bytes on the disk. create table p (a int[]) partition by list (a); CREATE TABLE select pg_table_size('p'); pg_table_size --------------- 8192 (1 row) select pg_relation_size(c1.oid) as p_size, pg_relation_size(c1.reltoastrelid) as p_toast_heap_size, pg_relation_size(c2.oid) as p_toast_index_size from pg_class c1, pg_class c2, pg_index i where c1.relname = 'p' and c1.reltoastrelid = i.indrelid and c2.oid = i.indexrelid; p_size | p_toast_heap_size | p_toast_index_size --------+-------------------+-------------------- 0 | 0 | 8192 (1 row) I think we should prevent this, a fix for which is implemented by the attached patch. Thanks, Amit -
Re: TOAST table created for partitioned tables
Robert Haas <robertmhaas@gmail.com> — 2018-01-16T20:32:35Z
On Tue, Jan 16, 2018 at 5:13 AM, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote: > I used to think that $subject didn't happen, but it actually does and ends > up consuming a fixed 8192 bytes on the disk. > > create table p (a int[]) partition by list (a); > CREATE TABLE > > select pg_table_size('p'); > pg_table_size > --------------- > 8192 > (1 row) > > select pg_relation_size(c1.oid) as p_size, > pg_relation_size(c1.reltoastrelid) as p_toast_heap_size, > pg_relation_size(c2.oid) as p_toast_index_size > from pg_class c1, pg_class c2, pg_index i > where c1.relname = 'p' and > c1.reltoastrelid = i.indrelid and > c2.oid = i.indexrelid; > p_size | p_toast_heap_size | p_toast_index_size > --------+-------------------+-------------------- > 0 | 0 | 8192 > (1 row) Aargh. Will apply this patch break pg_upgrade from v10? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -
Re: TOAST table created for partitioned tables
Amit Langote <amitlangote09@gmail.com> — 2018-01-17T04:09:52Z
On Wed, Jan 17, 2018 at 5:32 AM, Robert Haas <robertmhaas@gmail.com> wrote: > On Tue, Jan 16, 2018 at 5:13 AM, Amit Langote > <Langote_Amit_f8@lab.ntt.co.jp> wrote: >> I used to think that $subject didn't happen, but it actually does and ends >> up consuming a fixed 8192 bytes on the disk. >> >> create table p (a int[]) partition by list (a); >> CREATE TABLE >> >> select pg_table_size('p'); >> pg_table_size >> --------------- >> 8192 >> (1 row) >> >> select pg_relation_size(c1.oid) as p_size, >> pg_relation_size(c1.reltoastrelid) as p_toast_heap_size, >> pg_relation_size(c2.oid) as p_toast_index_size >> from pg_class c1, pg_class c2, pg_index i >> where c1.relname = 'p' and >> c1.reltoastrelid = i.indrelid and >> c2.oid = i.indexrelid; >> p_size | p_toast_heap_size | p_toast_index_size >> --------+-------------------+-------------------- >> 0 | 0 | 8192 >> (1 row) > > Aargh. Will apply this patch break pg_upgrade from v10? AFAICS, it doesn't. Partitioned tables that used to have a TOAST table in v10 cluster will continue to have it after upgrading. Whereas, any partitioned tables created with the patched won't have a TOAST table. Thanks, Amit -
Re: TOAST table created for partitioned tables
Tom Lane <tgl@sss.pgh.pa.us> — 2018-01-17T04:38:58Z
Amit Langote <amitlangote09@gmail.com> writes: > On Wed, Jan 17, 2018 at 5:32 AM, Robert Haas <robertmhaas@gmail.com> wrote: >> Aargh. Will apply this patch break pg_upgrade from v10? > AFAICS, it doesn't. Partitioned tables that used to have a TOAST > table in v10 cluster will continue to have it after upgrading. > Whereas, any partitioned tables created with the patched won't have a > TOAST table. Yeah, pg_upgrade already has to cope with cases where the newer version thinks a table needs a toast table when the older version didn't, or vice versa. This looks like it ought to fall into that category. Not that testing it wouldn't be a good idea. regards, tom lane
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Re: TOAST table created for partitioned tables
Michael Paquier <michael.paquier@gmail.com> — 2018-01-17T04:51:06Z
On Tue, Jan 16, 2018 at 11:38:58PM -0500, Tom Lane wrote: > Yeah, pg_upgrade already has to cope with cases where the newer version > thinks a table needs a toast table when the older version didn't, or > vice versa. This looks like it ought to fall into that category. > Not that testing it wouldn't be a good idea. As far as I can see this statement is true. If you create a parent partition table in a v10 cluster, and then upgrade to HEAD with this patch applied, you'll be able to notice that the relation still has its toast table present, while newly-created parent partitions would have nothing. (Just tested, I didn't review the patch in details). -- Michael
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Re: TOAST table created for partitioned tables
Amit Langote <amitlangote09@gmail.com> — 2018-01-17T06:03:24Z
On Wed, Jan 17, 2018 at 1:51 PM, Michael Paquier <michael.paquier@gmail.com> wrote: > On Tue, Jan 16, 2018 at 11:38:58PM -0500, Tom Lane wrote: >> Yeah, pg_upgrade already has to cope with cases where the newer version >> thinks a table needs a toast table when the older version didn't, or >> vice versa. This looks like it ought to fall into that category. >> Not that testing it wouldn't be a good idea. > > As far as I can see this statement is true. If you create a parent > partition table in a v10 cluster, and then upgrade to HEAD with this > patch applied, you'll be able to notice that the relation still has its > toast table present, while newly-created parent partitions would have > nothing. (Just tested, I didn't review the patch in details). Thanks for checking. I too checked that pg_upgrading v10 cluster containing partitioned tables that have a TOAST table attached to it works normally and like Michael says, the TOAST table remains. Thanks, Amit
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Re: TOAST table created for partitioned tables
Robert Haas <robertmhaas@gmail.com> — 2018-03-22T17:51:26Z
On Wed, Jan 17, 2018 at 1:03 AM, Amit Langote <amitlangote09@gmail.com> wrote: > On Wed, Jan 17, 2018 at 1:51 PM, Michael Paquier > <michael.paquier@gmail.com> wrote: >> On Tue, Jan 16, 2018 at 11:38:58PM -0500, Tom Lane wrote: >>> Yeah, pg_upgrade already has to cope with cases where the newer version >>> thinks a table needs a toast table when the older version didn't, or >>> vice versa. This looks like it ought to fall into that category. >>> Not that testing it wouldn't be a good idea. >> >> As far as I can see this statement is true. If you create a parent >> partition table in a v10 cluster, and then upgrade to HEAD with this >> patch applied, you'll be able to notice that the relation still has its >> toast table present, while newly-created parent partitions would have >> nothing. (Just tested, I didn't review the patch in details). > > Thanks for checking. I too checked that pg_upgrading v10 cluster > containing partitioned tables that have a TOAST table attached to it > works normally and like Michael says, the TOAST table remains. I have committed your patch. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
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Re: TOAST table created for partitioned tables
Amit Langote <langote_amit_f8@lab.ntt.co.jp> — 2018-03-23T00:28:57Z
On 2018/03/23 2:51, Robert Haas wrote: > On Wed, Jan 17, 2018 at 1:03 AM, Amit Langote <amitlangote09@gmail.com> wrote: >> On Wed, Jan 17, 2018 at 1:51 PM, Michael Paquier >> <michael.paquier@gmail.com> wrote: >>> On Tue, Jan 16, 2018 at 11:38:58PM -0500, Tom Lane wrote: >>>> Yeah, pg_upgrade already has to cope with cases where the newer version >>>> thinks a table needs a toast table when the older version didn't, or >>>> vice versa. This looks like it ought to fall into that category. >>>> Not that testing it wouldn't be a good idea. >>> >>> As far as I can see this statement is true. If you create a parent >>> partition table in a v10 cluster, and then upgrade to HEAD with this >>> patch applied, you'll be able to notice that the relation still has its >>> toast table present, while newly-created parent partitions would have >>> nothing. (Just tested, I didn't review the patch in details). >> >> Thanks for checking. I too checked that pg_upgrading v10 cluster >> containing partitioned tables that have a TOAST table attached to it >> works normally and like Michael says, the TOAST table remains. > > I have committed your patch. Thank you! Regards, Amit