2007/11/19, Josh Harrison <[EMAIL PROTECTED]>: > Hi, > I have a few questions about the storage and performance > > 1. How do you estimate the table size in postgresql? > For example if I have a table 'Dummy' with 1 varchar (40) & 1 > numeric(22,0) fields and 1000 rows, what is the tablesize estimate for > this (including the row overhead etc)? How many pages will this > occupy? > > 2. Also if the table contains null columns, does postgres allocates > the same space for these nulls columns? How does it handle 'nulls' in > terms of storage?
Try these: http://www.postgresql.org/docs/current/static/datatype-numeric.html http://www.postgresql.org/docs/current/static/datatype-character.html http://www.postgresql.org/docs/current/static/storage-page-layout.html ad.1 ) There is a fixed-size header (occupying 27 bytes on most machines) for each tuple so you will have about 27 + 1 + varchar data + numeric data per row, plus some overhaed for block headers ad.2 ) there is a null bitmap for each tuple which has nullable fields - so every 8 NULLable columns occupy one byte bitmap. PS. why do you post same thing many times? this is kinda.. spam? -- Filip Rembiałkowski ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
