DB Files

On 11/15/24 06:27, Andy Hartman wrote:

I created a  new table (V16) and then used SimplySql to take data from
mssql to the new Postgres table. The table is 212gig in size. Myquestion
comes from the files created on the OS(Windows2022 server) I can see
lots of files with the last being:

2474695.143

They are all 1,048,576kb

Is this normal behaviour and could I have done something to use fewer
files and larger ones?

Read:

https://www.postgresql.org/docs/current/storage-file-layout.html

[...]

"When a table or index exceeds 1 GB, it is divided into gigabyte-sized
segments. The first segment's file name is the same as the filenode;
subsequent segments are named filenode.1, filenode.2, etc. This
arrangement avoids problems on platforms that have file size
limitations. (Actually, 1 GB is just the default segment size. The
segment size can be adjusted using the configuration option
--with-segsize when building PostgreSQL.) In principle, free space map
and visibility map forks could require multiple segments as well, though
this is unlikely to happen in practice."

[...]

This table is created in a separate tablespace on a dedicated drive on
the windows file system.

 I'm just getting involved in this PostgreSql instance

THanks.

--
Adrian Klaver
adrian.klaver@aklaver.com

PG normally splits table data into 1GB chunks. The number before the dot is
called the filenode. You can translate it into a table name by

select oid::regclass::text from pg_class where relfilenode='2474695';

I believe there is an option to change that chunk size but you'd have to
recompile Postgres. The setting you need to change is called segment_size.

See https://www.postgresql.org/docs/current/runtime-config-preset.html

On Fri, Nov 15, 2024 at 3:27 PM Andy Hartman <hartman60home@gmail.com>
wrote:

Thanks... I just found that myself... so normal behavior then...

On Fri, Nov 15, 2024 at 10:47 AM Adrian Klaver <adrian.klaver@aklaver.com>
wrote: