From 865d26fdd632890167035dac905b6379d4383209 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Mon, 18 Feb 2002 05:09:01 +0000 Subject: Update FAQ. --- doc/src/FAQ/FAQ.html | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) (limited to 'doc/src') diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index 9ad2d5089c2..2f5cf11f460 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -14,7 +14,7 @@ alink="#0000ff">

Frequently Asked Questions (FAQ) for PostgreSQL

-

Last updated: Thu Feb 14 12:14:47 EST 2002

+

Last updated: Mon Feb 18 00:08:54 EST 2002

Current maintainer: Bruce Momjian (pgman@candle.pha.pa.us)
@@ -855,27 +855,27 @@

As an example, consider a file of 100,000 lines with an integer and text description on each line. Suppose the text string avergages - twenty characters in length. The flat file would be 2.8 MB. The size + 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 6.6 MB:

+ estimated as 6.4 MB:

     36 bytes: each row header (approximate)
-    26 bytes: two int fields @ 4 bytes each
+    24 bytes: one int field and one text filed
    + 4 bytes: pointer on page to tuple
    ----------------------------------------
-    66 bytes per row
+    64 bytes per row
 
    The data page size in PostgreSQL is 8192 bytes (8 KB), so:
 
    8192 bytes per page
-   -------------------   =  124 rows per database page (rounded down)
-     66 bytes per row
+   -------------------   =  128 rows per database page (rounded down)
+     64 bytes per row
 
    100000 data rows
-   --------------------  =  807 database pages (rounded up)
-      124 rows per page
+   --------------------  =  782 database pages (rounded up)
+      128 rows per page
 
-807 database pages * 8192 bytes per page  =  6,610,944 bytes (6.6 MB)
+782 database pages * 8192 bytes per page  =  6,406,144 bytes (6.4 MB)
 

Indexes do not require as much overhead, but do contain the data -- cgit v1.2.3