pg_appendonly

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

column	type	references	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.
compresslevel	smallint		The compression level, with 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		A checksum value that is stored to compare the state of a block of data at compression time and at scan time to ensure data integrity.
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		1 for column-oriented storage, 0 for row-oriented storage.
segrelid	oid		Table on-disk segment file id.
segfilecount	smallint		Number of segment files.
version	smallint		Version of the append-optimized table.
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.