Cleans and analyzes a database.
VACUUM [ VERBOSE ] [ ANALYZE ] [ table ] VACUUM [ VERBOSE ] ANALYZE [ table [ (column [, ...] ) ] ]
VERBOSE
The keyword that causes VACUUM
to display an activity report for
each table it operates upon.
ANALYZE
The keyword that causes VACUUM
to update column statistics for the
optimizer.
table
A table you intend to vacuum. If you do not specify a table, VACUUM
will operate upon all tables.
column
The name of a column to analyze (used when updating statistics for the optimizer).
VACUUM
The message returned when a VACUUM
successfully vacuums a database
or table.
NOTICE: —Relation table—
The notice returned when VACUUM
begins cleaning a table
(table
) while in verbose mode.
NOTICE: Pages 1: Changed 1, reaped 1, Empty 0, New 0; Tup 12: Vac 39,
Keep/VTL 0/0, Crash 0, UnUsed 0, MinLen 52, MaxLen 76; Re-using: Free/Avail. Space 7180/0;
EndEmpty/Avail. Pages 0/0. CPU 0.00s/0.00u sec.
The notice returned from the analysis on a table.
NOTICE: Index
indexname
: Pages 2; Tuples 12: Deleted 39.
CPU 0.00s/0.00u sec.
The notice returned from an analysis of indexname
.
Use the VACUUM
command to clean up records from rolled back
transactions and to update system catalog statistics. Call it with the ANALYZE
option to collect statistical information about data. Using this command
periodically can increase the performance of your database.
The following example displays the output of the VACUUM
command when
run on the books
table with the VERBOSE
keyword:
booktown=# VACUUM VERBOSE books;
NOTICE: --Relation books--
NOTICE: Pages 1: Changed 0, reaped 1, Empty 0, New 0; Tup 15:
Vac 0, Keep/VTL 0/0, Crash 0, UnUsed 5, MinLen 52,
MaxLen 76; Re-using: Free/Avail. Space 7108/0;
EndEmpty/Avail. Pages 0/0. CPU 0.00s/0.00u sec.
NOTICE: Index books_id_pkey: Pages 2; Tuples 15: Deleted 0.
CPU 0.00s/0.00u sec.
3.133.128.145