diff options
| author | Bruce Momjian | 2005-09-01 16:18:08 +0000 |
|---|---|---|
| committer | Bruce Momjian | 2005-09-01 16:18:08 +0000 |
| commit | fc9b6451a5ee4ae88cf751c7923f270dd50be0c1 (patch) | |
| tree | 9daa2704f1f4024ae2021a06f758b81ecf15ad01 /doc/FAQ | |
| parent | 14720f7c5709f10dbac56e0ff26d9d373904735d (diff) | |
Update disk space computation because oids are now optional.
Diffstat (limited to 'doc/FAQ')
| -rw-r--r-- | doc/FAQ | 16 |
1 files changed, 8 insertions, 8 deletions
@@ -1,7 +1,7 @@ Frequently Asked Questions (FAQ) for PostgreSQL - Last updated: Thu Aug 11 09:21:58 EDT 2005 + Last updated: Thu Sep 1 12:17:52 EDT 2005 Current maintainer: Bruce Momjian ([email protected]) @@ -489,23 +489,23 @@ twenty bytes in length. The flat file would be 2.8 MB. The size of the PostgreSQL database file containing this data can be estimated as 6.4 MB: - 32 bytes: each row header (approximate) + 28 bytes: each row header (approximate) 24 bytes: one int field and one text field + 4 bytes: pointer on page to tuple ---------------------------------------- - 60 bytes per row + 56 bytes per row The data page size in PostgreSQL is 8192 bytes (8 KB), so: 8192 bytes per page - ------------------- = 136 rows per database page (rounded down) - 60 bytes per row + ------------------- = 146 rows per database page (rounded down) + 56 bytes per row 100000 data rows - -------------------- = 735 database pages (rounded up) - 128 rows per page + -------------------- = 685 database pages (rounded up) + 146 rows per page -735 database pages * 8192 bytes per page = 6,021,120 bytes (6 MB) +685 database pages * 8192 bytes per page = 5,611,520 bytes (5.6 MB) Indexes do not require as much overhead, but do contain the data that is being indexed, so they can be large also. |