Re: Index file is growing when I drop a table. Why?

Pg 15.4

I'm dropping the large table "bar" in a test database, and it's taking a long time.  Thus, I thought I'd watch it deleting files.

To my surprise, though, the files that store the index are growing.  What's up with that?

What does pg_locks show ?

SELECT blocked_locks.pid AS blocked_pid,
   blocked_activity.usename AS blocked_user,
   blocking_locks.pid AS blocking_pid,
   blocking_activity.usename AS blocking_user,
   blocked_activity.query AS blocked_statement,
   blocking_activity.query AS blocked_by
  FROM pg_locks blocked_locks
    JOIN pg_stat_activity blocked_activity ON blocked_activity.pid = blocked_locks.pid
    JOIN pg_locks blocking_locks ON blocking_locks.locktype = blocked_locks.locktype AND NOT blocking_locks.database IS DISTINCT FROM blocked_locks.database
AND NOT blocking_locks.relation IS DISTINCT FROM blocked_locks.relation AND NOT blocking_locks.page IS DISTINCT FROM blocked_locks.page AND NOT blocking_loc
ks.tuple IS DISTINCT FROM blocked_locks.tuple AND NOT blocking_locks.virtualxid IS DISTINCT FROM blocked_locks.virtualxid AND NOT blocking_locks.transactioni
d IS DISTINCT FROM blocked_locks.transactionid AND NOT blocking_locks.classid IS DISTINCT FROM blocked_locks.classid AND NOT blocking_locks.objid IS DISTINCT
FROM blocked_locks.objid AND NOT blocking_locks.objsubid IS DISTINCT FROM blocked_locks.objsubid AND blocking_locks.pid <> blocked_locks.pid
    JOIN pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
 WHERE NOT blocked_locks.granted;

foo=# select * from pg_class where oid = 41533;
-[ RECORD 1 ]-------+----------
oid                 | 41533
relname             | i_bar_su1
relnamespace        | 2200

$ pwd
/var/lib/pgsql/15/data/base/16482
$ la -aFl 41533*
-rw------- 1 postgres postgres 1073741824 2023-11-16 11:15:06 41533
-rw------- 1 postgres postgres  189792256 2023-11-16 11:24:15 41533.1

Five minutes later, 41533.1 is 4.3MB larger.

$ dir 41533* 
-rw------- 1 postgres postgres 1073741824 2023-11-16 11:15:06 41533
-rw------- 1 postgres postgres  194101248 2023-11-16 11:29:44 41533.1

-- 
Achilleas Mantzios IT DEV - HEAD IT DEPT Dynacom Tankers Mgmt