diff --git a/doc/FAQ b/doc/FAQ index 23994765bf..dae4beef81 100644 --- a/doc/FAQ +++ b/doc/FAQ @@ -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 (pgman@candle.pha.pa.us) @@ -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. diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index 2d46904eb3..d1e8af9f1e 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -10,7 +10,7 @@ alink="#0000ff">
Last updated: Thu Aug 11 09:21:58 EDT 2005
+Last updated: Thu Sep 1 12:17:52 EDT 2005
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) @@ -635,23 +635,23 @@ table?
- 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