diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml index 3234adb639f..bfccda77afd 100644 --- a/doc/src/sgml/storage.sgml +++ b/doc/src/sgml/storage.sgml @@ -394,9 +394,9 @@ Further details appear in . The compression technique used for either in-line or out-of-line compressed -data is a fairly simple and very fast member -of the LZ family of compression techniques. See -src/common/pg_lzcompress.c for the details. +data can be selected using the COMPRESSION option on a per-column +basis when creating a table. The default for columns with no explicit setting +is taken from the value of . @@ -425,8 +425,9 @@ retrieval of the values. A pointer datum representing an out-of-line on-disk TOASTed value therefore needs to store the OID of the TOAST table in which to look and the OID of the specific value (its chunk_id). For convenience, pointer datums also store the -logical datum size (original uncompressed data length) and physical stored size -(different if compression was applied). Allowing for the varlena header bytes, +logical datum size (original uncompressed data length), physical stored size +(different if compression was applied), and the compression method used, if +any. Allowing for the varlena header bytes, the total size of an on-disk TOAST pointer datum is therefore 18 bytes regardless of the actual size of the represented value.