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X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB6PR0502MB3014 X-OriginatorOrg: ed.ac.uk X-Edinburgh-Scanned: at loire.is.ed.ac.uk with MIMEDefang 2.78, Sophie, Sophos Anti-Virus, Clam AntiVirus X-Spam-Status: hits=0 required=5 tests=LOCAL_FROM_ED,T_RP_MATCHES_RCVD version=3.4.0 X-Scanned-By: MIMEDefang 2.78 on 129.215.16.10 List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org Hi, I have two tables s { id bigint NOT NULL PRIMARY KEY, ... } sp { id bigint PRIMARY KEY, sid bigint REFERENCES s (id), i numeric, m numeric ... } I have for each entry in [s] on average around 120 entries in [sp]. And that table has become the largest table in my database (8.81565*10^09 entries). Data in [sp] are never changed. I can probably reduce the size by changing datatypes from numeric to float but I was wondering if it would be more efficient - primarily in terms of storage - to change the structure to have two arrays in [s]. E.g. s { id bigint NOT NULL PRIMARY KEY, i numeric[], m numeric[], ... } I can probably reduce the size by changing datatypes from numeric to float/double. so final table would look like this: s { id bigint NOT NULL PRIMARY KEY, i float[], m double[], ... } I haven't really found anything yet how much space (e.g. how many bytes) an array will use compared to a table row in postgresql. Thanks Lutz -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance