Horton

Re: [Proposal] Fully WAL logged CREATE DATABASE - No Checkpoints

Greg Nancarrow <gregn4422@gmail.com>

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From: Greg Nancarrow <gregn4422@gmail.com>
To: Neha Sharma <neha.sharma@enterprisedb.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Heikki Linnakangas <hlinnaka@iki.fi>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-12-09T00:26:18Z
Lists: pgsql-hackers 
On Thu, Dec 9, 2021 at 6:57 AM Neha Sharma <neha.sharma@enterprisedb.com> wrote:
>
> While testing the v7 patches, I am observing a crash with the below test case.
>
> Test case:
> create tablespace tab location '<dir_path>/test_dir';
> create tablespace tab1 location '<dir_path>/test_dir1';
> create database test tablespace tab;
> \c test
> create table t( a int PRIMARY KEY,b text);
> CREATE OR REPLACE FUNCTION large_val() RETURNS TEXT LANGUAGE SQL AS 'select array_agg(md5(g::text))::text from generate_series(1, 256) g';
> insert into t values (generate_series(1,2000000), large_val());
> alter table t set tablespace tab1 ;
> \c postgres
> create database test1 template test;
> alter database test set tablespace pg_default;
> alter database test set tablespace tab;
> \c test1
> alter table t set tablespace tab;
>
>  Logfile says:
> 2021-12-08 23:31:58.855 +04 [134252] PANIC:  could not fsync file "base/16386/4152": No such file or directory
> 2021-12-08 23:31:59.398 +04 [134251] LOG:  checkpointer process (PID 134252) was terminated by signal 6: Aborted
>

I tried to reproduce the issue using your test scenario, but I needed
to reduce the amount of inserted data (so reduced 2000000 to 20000)
due to disk space.
I then consistently get an error like the following:

postgres=# alter database test set tablespace pg_default;
ERROR:  could not create file
"pg_tblspc/16385/PG_15_202111301/16386/36395": File exists

(this only happens when the patch is used)


Regards,
Greg Nancarrow
Fujitsu Australia

Commits

  1. When using the WAL-logged CREATE DATABASE strategy, bulk extend.

  2. Avoid using a fake relcache entry to own an SmgrRelation.

  3. Fix data-corruption hazard in WAL-logged CREATE DATABASE.

  4. initdb: When running CREATE DATABASE, use STRATEGY = WAL_COPY.

  5. Simplify a needlessly-complicated regular expression.

  6. In 020_createdb.pl, change order of command-line arguments.

  7. Add new block-by-block strategy for CREATE DATABASE.

  8. Fix replay of create database records on standby

  9. Refactor code for reading and writing relation map files.

  10. Replace RelationOpenSmgr() with RelationGetSmgr().

  11. Refactor the fsync queue for wider use.