TOAST table performance problem

Hello everybody,

I have trouble with my table that has four columns which their data types
are text, JSON, boolean and timestamp.

Also, I have 1K rows, but my JSON column size approximately 110KB and maybe
over it.

When I select all the data from my table, it takes 600 seconds.

But I explain my query;

*Seq Scan on zamazin (cost=0.00..21.77 rows=1077 width=49) (actual
time=0.004..0.112 rows=1077 loops=1)*

*Planning time: 0.013 ms*

*Execution time: 0.194 ms*

When I investigated why these execution times are so different, I find a
new storage logic like TOAST.

I overlook some details on TOAST logic and increased some config like
shared_buffers, work_mem, maintenance_work_mem, max_file_per_process.

But there was no performance improvement on my query.

I do not understand why it happens. My table size is 168 MB, but my TOAST
table size that is related to that table, is 123 MB.

*My environment is;*

PostgreSQL 9.4.1

Windows Server 2012 R2

16 GB RAM

100 GB HardDisk (Not SSD)

My database size 20 GB.

*My server configuration ;*

Shared_buffers: 8GB

( If I understand correctly, PostgreSQL says, For 9.4 The useful range for
shared_buffers on Windows systems is generally from 64MB to 512MB. Link:
https://www.postgresql.org/docs/9.4/runtime-config-resource.html )

work_mem : 512 MB

maintenance_work_mem: 1GB

max_file_per_process: 10000

effective_cache_size: 8GB

How I can achieve good performance?

Regards,

Mustafa BÜYÜKSOY