diff --git a/doc/FAQ b/doc/FAQ index b054d06914..3b9ec250a2 100644 --- a/doc/FAQ +++ b/doc/FAQ @@ -1,7 +1,7 @@ Frequently Asked Questions (FAQ) for PostgreSQL - Last updated: Mon Jul 19 16:28:37 EDT 2004 + Last updated: Mon Jul 26 23:27:08 EDT 2004 Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us) @@ -735,23 +735,23 @@ 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: - 36 bytes: each row header (approximate) + 32 bytes: each row header (approximate) 24 bytes: one int field and one text field + 4 bytes: pointer on page to tuple ---------------------------------------- - 64 bytes per row + 60 bytes per row The data page size in PostgreSQL is 8192 bytes (8 KB), so: 8192 bytes per page - ------------------- = 128 rows per database page (rounded down) - 64 bytes per row + ------------------- = 136 rows per database page (rounded down) + 60 bytes per row 100000 data rows - -------------------- = 782 database pages (rounded up) + -------------------- = 735 database pages (rounded up) 128 rows per page -782 database pages * 8192 bytes per page = 6,406,144 bytes (6.4 MB) +735 database pages * 8192 bytes per page = 6,021,120 bytes (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 c3e305c425..2272703f3c 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -10,7 +10,7 @@ alink="#0000ff">
Last updated: Mon Jul 19 16:28:37 EDT 2004
+Last updated: Mon Jul 26 23:27:08 EDT 2004
Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@@ -927,23 +927,23 @@
The size of the PostgreSQL database file containing this data can
be estimated as 6.4 MB:
- 36 bytes: each row header (approximate) + 32 bytes: each row header (approximate) 24 bytes: one int field and one text field + 4 bytes: pointer on page to tuple ---------------------------------------- - 64 bytes per row + 60 bytes per row The data page size in PostgreSQL is 8192 bytes (8 KB), so: 8192 bytes per page - ------------------- = 128 rows per database page (rounded down) - 64 bytes per row + ------------------- = 136 rows per database page (rounded down) + 60 bytes per row 100000 data rows - -------------------- = 782 database pages (rounded up) + -------------------- = 735 database pages (rounded up) 128 rows per page -782 database pages * 8192 bytes per page = 6,406,144 bytes (6.4 MB) +735 database pages * 8192 bytes per page = 6,021,120 bytes (6 MB)
Indexes do not require as much overhead, but do contain the data