May 17, 2026, 11:40 PM

inbox/DataBase/PostgreSQL/maintenance/vacuum_full.sql

@@ -0,0 +1,35 @@
+VACUUM FULL - > JUST LIKE MOVE COMMAND IN ORACLE . IT TAKES MORE TIME, BUT IT RETURNS THE SPACE TO OS BECAUSE OF ITS COMPLEX ALGORITHM. IT also requires additional disk space , which can store the new copy of the table., until the activity is completed. Also it locks the table exclusively, which block all operations on the table .
+
+-- Command to run vacuum full command for table:
+
+dbaclass=# VACUUM FULL dbatest.emptab;
+VACUUM
+
+ 
+
+DEMO TO CHECK HOW IT RECLAIMS SPACE:
+
+-- Check existing space and delete some data:
+dbaclass=# select pg_size_pretty(pg_relation_size('dbatest.emptab'));
+pg_size_pretty
+----------------
+114 MB
+(1 row)
+
+dbaclass=# delete from dbatest.emptab where oid=13634;
+DELETE 131072
+
+-- We can observe size is still same:
+
+dbaclass=# select pg_size_pretty(pg_relation_size('dbatest.emptab'));
+pg_size_pretty
+----------------
+114 MB
+(1 row)
+
+-- Run vacuum full and observe the space usage:
+
+dbaclass=# VACUUM FULL dbatest.emptab;
+VACUUM
+
+dbaclass=# select pg_size_pretty(pg_relation_size('dbatest.emptab'));