Perform scan on Toast table

Hi everyone ,I have a question. I have a table with large data (i was used
bytea datatype and insert a binary content to table ) so that Postgres help
me get a TOAST table to storage out-of-line values   .
Assume that my table is " tbl_test " and toast table oid is 16816

When i peform  EXPLAIN ANALYZE select  query on tbl_test ( EXPLAIN ANALYZE
SELECT * FROM tbl_test).It show that  sequential scan was performed on
tbl_test ,but when i check pg_toast table with this query :


SELECT
    relid,
    schemaname,
    relname,
    seq_scan,
    seq_tup_read,
    idx_scan,
FROM pg_stat_all_tables
WHERE relid IN  ( SELECT oid
    FROM pg_class
    WHERE relkind = 't' ) AND relid = 16816

I saw that  seq_tup_read = 0 and the seq_scan is always is 1 .idx_scan is
increase arcording to the number of query on tbl_test

 I was wordering : Do have a sequential scan perform on tbl_test and other
index scan will be peforming on TOAST after this sequential scan ?
Can you explain this dump question to me ,please ?
P/S : sorry for my bad English .Thanks  ! :)








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