如何在SQLite(w / Python)中优化多个嵌套SELECT？

我正在构建一个CGI脚本,用于轮询SQLite数据库并构建统计表.下面描述源数据库表,以及相关代码的块.一切正常(功能上),但CGI本身非常慢,因为我有多个嵌套的SELECT COUNT(id)调用.我认为我最好的优化是向SO社区提问,因为我与谷歌的时间相对无果而终.

桌子：

CREATE TABLE messages (
    id TEXT PRIMARY KEY ON CONFLICT REPLACE,date TEXT,hour INTEGER,sender TEXT,size INTEGER,origin TEXT,destination TEXT,relay TEXT,day TEXT);

(是的,我知道这个表没有标准化,但它填充了邮件日志中的摘录……我很高兴得到提取和填充工作,更不用说规范化了.我不认为表结构有在这一点上与我的问题有很多关系,但我可能是错的.)

样本行：

476793200A7|Jan 29 06:04:47|6|admin@mydomain.com|4656|web02.mydomain.pvt|user@example.com|mail01.mydomain.pvt|Jan 29

而且,构建我的表的Python代码：

#!/usr/bin/python
print 'Content-type: text/htmlnn'

from datetime import date

import re
p = re.compile('(w+) (d+)')

d_month = {'Jan':1,'Feb':2,'Mar':3,'Apr':4,'May':5,'Jun':6,'Jul':7,'Aug':8,'Sep':9,'Oct':10,'Nov':11,'Dec':12}
l_wkday = ['Mo','Tu','We','Th','Fr','Sa','Su']

days = []
curs.execute('SELECT DISTINCT(day) FROM messages ORDER BY day')
for day in curs.fetchall():
    m = p.match(day[0]).group(1)
    m = d_month[m]
    d = p.match(day[0]).group(2)
    days.append([day[0],"%s (%s)" % (day[0],l_wkday[date.weekday(date(2010,int(m),int(d)))])])

curs.execute('SELECT DISTINCT(sender) FROM messages')
senders = curs.fetchall()
for sender in senders:
    curs.execute('SELECT COUNT(id) FROM messages WHERE sender=%s',(sender[0]))
    print '  

my %data;
my $rows = $db->selectall_arrayref("SELECT COUNT(id),sender,day,hour FROM messages GROUP BY sender,hour ORDER BY sender,hour");
for my $row (@$rows) {
    my ($ct,$se,$dy,$hr) = @$row;
    $data{$se}{$dy}{$hr} = $ct;
}
for my $se (keys %data) {
    print "Sender: $sen";
    for my $dy (keys %{$data{$se}}) {
    print "Day: ",time2str('%a',str2time("$dy 2010"))," $dyn";
        for my $hr (keys %{$data{$se}{$dy}}) {
            print "Hour: $hr = ".$data{$se}{$dy}{$hr}."n";
        }
    }
    print "n";
}