Re: Pluggable toaster - Mailing list pgsql-hackers

From Nikita Malakhov
Subject Re: Pluggable toaster
Date
Msg-id CAN-LCVPWkZCbTERTHC5+gOXDJwsekMXHkDJ6p_Hp4u-tw1fTjQ@mail.gmail.com
Whole thread Raw
In response to Re: Pluggable toaster  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Hi,
Thanks for advices.
We have 4 branches, for each patch provided, you can check them out -
(come copy-paste from the very fist email, where the patches were proposed)
1) 1_toaster_interface
https://github.com/postgrespro/postgres/tree/toaster_interface
Introduces syntax for storage and formal toaster API. Adds column
atttoaster to pg_attribute, by design this column should not be equal to
invalid oid for any toastable datatype, ie it must have correct oid for
any type (not column) with non-plain storage. Since  toaster may support
only particular datatype, core should check correctness of toaster set
by toaster validate method. New commands could be found in
src/test/regress/sql/toaster.sql. Also includes modification of pg_dump.

2) 2_toaster_default
https://github.com/postgrespro/postgres/tree/toaster_default
Built-in toaster implemented (with some refactoring)  using toaster API
as generic (or default) toaster.  dummy_toaster here is a minimal
workable example, it saves value directly in toast pointer and fails if
value is greater than 1kb.

3) 3_toaster_snapshot
https://github.com/postgrespro/postgres/tree/toaster_snapshot
The patch implements technology to distinguish row's versions in toasted
values to share common parts of toasted values between different
versions of rows

4) 4_bytea_appendable_toaster
https://github.com/postgrespro/postgres/tree/bytea_appendable_toaster
Contrib module implements toaster for non-compressed bytea columns,
which allows fast appending to existing bytea value. Appended tail
stored directly in toaster pointer, if there is enough space to do it.

Working on refactoring according to your recommendations.
Thank you!

On Mon, Apr 4, 2022 at 11:18 PM Robert Haas <robertmhaas@gmail.com> wrote:
On Mon, Apr 4, 2022 at 4:05 PM Nikita Malakhov <hukutoc@gmail.com> wrote:
> - Is 'git apply' not a valid way to apply such patches?

I have found that it never works. This case is no exception:

[rhaas pgsql]$ git apply ~/Downloads/1_toaster_interface_v4.patch
/Users/rhaas/Downloads/1_toaster_interface_v4.patch:253: trailing whitespace.
toasterapi.o
/Users/rhaas/Downloads/1_toaster_interface_v4.patch:1276: trailing whitespace.
{
/Users/rhaas/Downloads/1_toaster_interface_v4.patch:1294: trailing whitespace.
 * CREATE TOASTER name HANDLER handler_name
/Users/rhaas/Downloads/1_toaster_interface_v4.patch:2261: trailing whitespace.
 * va_toasterdata could contain varatt_external structure for old Toast
/Users/rhaas/Downloads/1_toaster_interface_v4.patch:3047: trailing whitespace.
SELECT attnum, attname, atttypid, attstorage, tsrname
error: patch failed: src/backend/commands/tablecmds.c:42
error: src/backend/commands/tablecmds.c: patch does not apply
error: patch failed: src/backend/commands/tablecmds.c:943
error: src/backend/commands/tablecmds.c: patch does not apply
error: patch failed: src/backend/commands/tablecmds.c:973
error: src/backend/commands/tablecmds.c: patch does not apply
error: patch failed: src/backend/commands/tablecmds.c:44
error: src/backend/commands/tablecmds.c: patch does not apply

I would really encourage you to use 'git format-patch' to generate a
stack of patches. But there is no point in reposting 30+ patches that
haven't been properly refactored into separate chunks. You need to
maintain a branch, periodically rebased over master, with some
probably-small number of patches on it, each of which is a logically
independent patch with its own commit message, its own clear purpose,
etc. And then generate patches to post from there using 'git
format-patch'. Look into using 'git rebase -i --autosquash' and 'git
commit --fixup' to maintain the branch, if you're not already familiar
with those things.

Also, it is a really good idea when you post the patch set to include
in the email a clear description of the overall purpose of the patch
set and what each patch does toward that goal. e.g. "The overall goal
of this patch set is to support faster-than-light travel. Currently,
PostgreSQL does not know anything about the speed of light, so 0001
adds some code for speed-of-light detection. Building on this, 0002
adds general support for disabling physical laws of the universe.
Then, 0003 makes use of this support to disable specifically the speed
of light." Perhaps you want a little more text than that for each
patch, depending on the situation, but this gives you the idea, I
hope.

--
Robert Haas
EDB: http://www.enterprisedb.com


--
Regards,
Nikita Malakhov
Postgres Professional 

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