pg_appendonly

The pg_appendonly table contains information about the storage options and other characteristics of append-optimized tables.

Column Type Description

Column	Type	Description
relid	oid	The table object identifier (OID) of the table
blocksize	integer	Block size used for compression of append-optimized tables. Valid values are `8K` - `2M`. Default is `32K`
safefswritesize	integer	Minimum size for safe write operations to append-optimized tables in a non-mature file system. Commonly set to a multiple of the extent size of the file system; for example, Linux ext3 is 4096 bytes, so a value of 32768 is commonly used
compresslevel	smallint	The compression level, with the compression ratio increasing from `1` to `19`. With `zlib` specified, valid values are `1`-`9`. When `zstd` is specified, valid values are `1`-`19`
checksum	boolean	`true` if a checksum is stored with the data and automatically checked during scans
compresstype	name	Type of compression used to compress append-optimized tables. Valid values are: `none` (no compression). `rle_type` (run-length encoding compression). `zlib` (gzip compression). `zstd` (Zstandard compression).
columnstore	boolean	`t` for column-oriented storage, `f` for row-oriented storage
segrelid	oid	Table on-disk segment file ID
blkdirrelid	oid	Block used for on-disk column-oriented table file
blkdiridxid	oid	Block used for on-disk column-oriented index file
visimaprelid	oid	Visibility map for the table
visimapidxid	oid	B-tree index on the visibility map

relid

oid

The table object identifier (OID) of the table

blocksize

integer

Block size used for compression of append-optimized tables. Valid values are 8K - 2M. Default is 32K

safefswritesize

integer

Minimum size for safe write operations to append-optimized tables in a non-mature file system. Commonly set to a multiple of the extent size of the file system; for example, Linux ext3 is 4096 bytes, so a value of 32768 is commonly used

compresslevel

smallint

The compression level, with the compression ratio increasing from 1 to 19. With zlib specified, valid values are 1-9. When zstd is specified, valid values are 1-19

checksum

boolean

true if a checksum is stored with the data and automatically checked during scans

compresstype

name

Type of compression used to compress append-optimized tables. Valid values are:

none (no compression).
rle_type (run-length encoding compression).
zlib (gzip compression).
zstd (Zstandard compression).

columnstore

boolean

t for column-oriented storage, f for row-oriented storage

segrelid

oid

Table on-disk segment file ID

blkdirrelid

oid

Block used for on-disk column-oriented table file

blkdiridxid

oid

Block used for on-disk column-oriented index file

visimaprelid

oid

Visibility map for the table

visimapidxid

oid

B-tree index on the visibility map

pg_amproc

pg_attrdef