January 2002
Intermediate to advanced
640 pages
16h 39m
English
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Vacuum
Cleans and analyzes a database.
Synopsis
VACUUM [ VERBOSE ] [ ANALYZE ] [ table ] VACUUM [ VERBOSE ] ANALYZE [ table [ (column [, ...] ) ] ]
Parameters
VERBOSEThe keyword that causes
VACUUMto display an activity report for each table it operates upon.ANALYZEThe keyword that causes
VACUUMto update column statistics for the optimizer.tableA table you intend to vacuum. If you do not specify a table,
VACUUMwill operate upon all tables.columnThe name of a column to analyze (used when updating statistics for the optimizer).
Results
VACUUMThe message returned when a
VACUUMsuccessfully vacuums a database or table.NOTICE: —Relation table—The notice returned when
VACUUMbegins 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: Indexindexname: Pages 2; Tuples 12: Deleted 39. CPU 0.00s/0.00u sec.The notice returned from an analysis of
indexname.
Description
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.
Example
The following example displays the output of the VACUUM command when
run on the books table with the ...