整個表更新

Question

目前我們使用MySQL。我們有空間索引表（所以沒有InnoDB），並且每x秒執行整個表更新（將對象從一個地方移動到另一個地方）。

目前我們做的：

UPDATE LOW_PRIORITY IGNORE `table` 
SET `column1` = CASE `column2` 
       WHEN 1 THEN ... 
       WHEN 2 THEN ... 
       WHEN 3 THEN ... 
       ... 
       ELSE `column1` 
       END; 

，但它得到的行數增加痛苦萬分。是否有更好的方法來完成整個表更新？也許我們應該切換到其他數據庫（PostGIS，NoSQL）？

對此有何看法？

Answer 1

一次更新許多行的最好方法是：

• 創建臨時表
• 與（主鍵，新的值）有一個大的INSERT
• 更新表JOIN不是Temptable使用強制它（主鍵）SET table.oldvalue = temptable.newvalue

更新：

create table test (id integer primary key, p point not null); 
insert into test (id,p) select id, POINT(id%100, floor(id/100)) from serie limit 10000; 
alter table test add spatial index spi (p); 
select id, AsText(p) from test; 

+----+-------------+ 
| id | AsText(p) | 
+----+-------------+ 
| 1 | POINT(1 0) | 
| 2 | POINT(2 0) | 
| 3 | POINT(3 0) | 
... 

| 98 | POINT(98 0) | 
| 99 | POINT(99 0) | 
| 100 | POINT(0 1) | 
| 101 | POINT(1 1) | 
... 

| 9999 | POINT(99 99) | 
| 10000 | POINT(0 100) | 
+-------+--------------+ 


EXPLAIN SELECT id,AsText(p) from test where Contains(GeomFromText('POLYGON((0 0,0 10,10 10,10 0,0 0))'), p); 
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+ 
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra  | 
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+ 
| 1 | SIMPLE  | test | range | spi   | spi | 34  | NULL | 112 | Using where | 
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+ 

create temporary table test2 (id integer primary key, p point not null); 
insert into test2 (id,p) select id, POINT(1+(id%100), 1+floor(id/100)) from serie limit 10000; 
update test, test2 set test.p=test2.p where test.id=test2.id; 

EXPLAIN SELECT id,AsText(p) from test where Contains(GeomFromText('POLYGON((0 0,0 10,10 10,10 0,0 0))'), p); 
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+ 
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra  | 
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+ 
| 1 | SIMPLE  | test | range | spi   | spi | 34  | NULL | 102 | Using where | 
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+ 

這裏沒問題（MySQL 5.1.41）