您是否观察到PostgreSQL临时表自8.3以来的性能下降?

我的应用程序在PostgreSQL中使用临时表。 在新的8.4版本中,我测试了它的性能 对于旧的8.2版本,我观察到临时表 是 十 慢一倍!

8.3版本的测试表明,8.3版本的速度也较慢。我比较了所有配置 碱基和它们相似。所有的基础都是一样的 服务器。当我的应用程序使用jdbc驱动程序时,我使用了jython 测试它:

import time
import traceback
import sys

from java.sql import DriverManager
from java.lang import Class

Class.forName("org.postgresql.Driver")

def test_bench(db, temp):
    if temp:
        temp_str = ' TEMP '
        temp_desc = 'temp   '
    else:
        temp_str = ' '
        temp_desc = 'regular'
    try:
        c = db.createStatement()
        c.execute("CREATE %s TABLE test_table_md_speed(id serial primary key, txt varchar(100))" % temp_str)
        cnt = '?'
        try:
            t0 = time.time()
            for i in range(1000):
                c.execute("INSERT INTO test_table_md_speed(txt) VALUES ('ala ma %d kota')" % i)
            t2 = time.time()
            rs = c.executeQuery("SELECT COUNT(*) AS ile FROM test_table_md_speed")
            while (rs.next()):
                cnt = rs.getString(1)
            print("%s\ttime: %7.3f [s]\tcnt: %s" % (temp_desc, (t2-t0), cnt))
        finally:
            c.execute("DROP TABLE test_table_md_speed")
        c.close()
    except:
        print("\nthere were errors!")
        s = traceback.format_exc()
        sys.stderr.write("%s\n" % (s))

def test_db(db_url, usr, passwd):
    print("\n\n--------------")
    db = DriverManager.getConnection(db_url, usr, passwd)
    try:
        c = db.createStatement()
        rs = c.executeQuery("SELECT version()")
        while (rs.next()):
            print('ver: %s' % (rs.getString(1)))
        test_bench(db, 0)
        test_bench(db, 1)
    finally:
        db.close()

test_db('jdbc:postgresql://db-test64:5432/db_stable?stringtype=unspecified', 'postgres', 'postgres')
test_db('jdbc:postgresql://db-test64:5434/db_stable?stringtype=unspecified', 'postgres', 'postgres')
test_db('jdbc:postgresql://db-test64:5435/db_stable?stringtype=unspecified', 'postgres', 'postgres')

我还使用activepython和来自win32的odbc编写了类似的测试,这个程序显示了相同的结果。 我的结果是:

C:\tools\pyscripts\>jython jdbc_pg_bench.py
--------------
ver: PostgreSQL 8.2.12 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
regular time:  12.016 [s]       cnt: 1000
temp    time:   1.187 [s]       cnt: 1000
--------------
ver: PostgreSQL 8.3.6 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
regular time:  11.922 [s]       cnt: 1000
temp    time:  10.516 [s]       cnt: 1000
--------------
ver: PostgreSQL 8.4.0 on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.1.2 20061115 (prerelease) (Debian 4.1.1-21), 64-bit
regular time:  13.375 [s]       cnt: 1000
temp    time:  13.609 [s]       cnt: 1000

在8.3和8.4版本中,您是否观察到相同的温度表速度降级? 有没有关于临时表行为变化的信息?

编辑

我在我的windows机器上安装了postgresql 8.2和8.4,并用10000个插件进行了测试,使用临时表8.2似乎更快:

ver: PostgreSQL 8.2.11 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC) 3.4.2 (mingw-special)
regular time:  40.672 [s]       cnt: 10000
temp    time:  14.859 [s]       cnt: 10000

ver: PostgreSQL 8.4.0, compiled by Visual C++ build 1400, 32-bit
regular time:  56.860 [s]       cnt: 10000
temp    time:  49.110 [s]       cnt: 10000