digoal
2016-03-02
PostgreSQL , pg_trgm , 倒排索引 , reverse , like , 正则匹配 , 模糊查询 , gin索引
正则匹配和模糊匹配通常是搜索引擎的特长，但是如果你使用的是 PostgreSQL 数据库照样能实现，并且性能不赖，加上分布式方案 (譬如 plproxy, pg_shard, fdw shard, pg-xc, pg-xl, greenplum)，处理百亿以上数据量的正则匹配和模糊匹配效果杠杠的，同时还不失数据库固有的功能，一举多得。
物联网中有大量的数据，除了数字数据，还有字符串类的数据，例如条形码，车牌，手机号，邮箱，姓名等等。
假设用户需要在大量的传感数据中进行模糊检索，甚至规则表达式匹配，有什么高效的方法呢？
这种场景还挺多，例如市面上发现了一批药品可能有问题，需要对药品条码进行规则表达式查找，找出复合条件的药品流向。
又比如在侦查行动时，线索的检索，如用户提供的残缺的电话号码，邮箱，车牌，IP地址，QQ号码，微信号码等等。
根据这些信息加上时间的叠加，模糊匹配和关联，最终找出罪犯。
可以看出，模糊匹配，正则表达式匹配，和人脸拼图有点类似，需求非常的迫切。
首先对应用场景进行一下分类，以及现有技术下能使用的优化手段。
1. 带前缀的模糊查询，例如 like 'ABC%'，在PG中也可以写成 ~ '^ABC'
可以使用btree索引优化，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
2. 带后缀的模糊查询，例如 like '%ABC'，在PG中也可以写成 ~ 'ABC$'
可以使用reverse函数btree索引，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
3. 不带前缀和后缀的模糊查询，例如 like '%AB_C%'，在PG中也可以写成 ~ 'AB.C'
可以使用pg_trgm的gin索引，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
4. 正则表达式查询，例如 ~ '[\d]+def1.?[a|b|0|8]{1,3}'
可以使用pg_trgm的gin索引，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
PostgreSQL pg_trgm插件自从9.1开始支持模糊查询使用索引，从9.3开始支持规则表达式查询使用索引，大大提高了PostgreSQL在刑侦方面的能力。
代码见
https://github.com/postgrespro/pg_trgm_pro
pg_trgm插件的原理，将字符串前加2个空格，后加1个空格，组成一个新的字符串，并将这个新的字符串按照每3个相邻的字符拆分成多个token。
当使用规则表达式或者模糊查询进行匹配时，会检索出他们的近似度，再进行filter。
GIN索引的图例：
从btree检索到匹配的token时，指向对应的list, 从list中存储的ctid找到对应的记录。
因为一个字符串会拆成很多个token，所以没插入一条记录，会更新多条索引，这也是GIN索引需要fastupdate的原因。
正则匹配是怎么做到的呢？
详见 https://raw.githubusercontent.com/postgrespro/pg_trgm_pro/master/trgm_regexp.c
实际上它是将正则表达式转换成了NFA格式，然后扫描多个TOKEN，进行bit and|or匹配。
正则组合如果转换出来的的bit and|or很多的话，就需要大量的recheck，性能也不能好到哪里去。
可以使用btree索引优化，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
例子，1000万随机产生的MD5数据的前8个字符。
postgres=# create table tb(info text);
CREATE TABLE
postgres=# insert into tb select substring(md5(random()::text),1,8) from generate_series(1,10000000);
INSERT 0 10000000
postgres=# create index idx_tb on tb(info);
CREATE INDEX
postgres=# select * from tb limit 1;
info
----------
376821ab
(1 row)
postgres=# explain select * from tb where info ~ '^376821' limit 10;
QUERY PLAN
-------------------------------------------------------------------------------
Limit (cost=0.43..0.52 rows=10 width=9)
-> Index Only Scan using idx_tb on tb (cost=0.43..8.46 rows=1000 width=9)
Index Cond: ((info >= '376821'::text) AND (info < '376822'::text))
Filter: (info ~ '^376821'::text)
(4 rows)
postgres=# select * from tb where info ~ '^376821' limit 10;
info
----------
376821ab
(1 row)
Time: 0.536 ms
postgres=# set enable_indexscan=off;
SET
Time: 1.344 ms
postgres=# set enable_bitmapscan=off;
SET
Time: 0.158 ms
postgres=# explain select * from tb where info ~ '^376821' limit 10;
QUERY PLAN
----------------------------------------------------------------
Limit (cost=0.00..1790.55 rows=10 width=9)
-> Seq Scan on tb (cost=0.00..179055.00 rows=1000 width=9)
Filter: (info ~ '^376821'::text)
(3 rows)
Time: 0.505 ms
带前缀的模糊查询，不使用索引需要5483毫秒。
带前缀的模糊查询，使用索引只需要0.5毫秒。
postgres=# select * from tb where info ~ '^376821' limit 10;
info
----------
376821ab
(1 row)
Time: 5483.655 ms
可以使用reverse函数btree索引，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
postgres=# create index idx_tb1 on tb(reverse(info));
CREATE INDEX
postgres=# explain select * from tb where reverse(info) ~ '^ba128' limit 10;
QUERY PLAN
--------------------------------------------------------------------------------------------
Limit (cost=0.43..28.19 rows=10 width=9)
-> Index Scan using idx_tb1 on tb (cost=0.43..138778.43 rows=50000 width=9)
Index Cond: ((reverse(info) >= 'ba128'::text) AND (reverse(info) < 'ba129'::text))
Filter: (reverse(info) ~ '^ba128'::text)
(4 rows)
postgres=# select * from tb where reverse(info) ~ '^ba128' limit 10;
info
----------
220821ab
671821ab
305821ab
e65821ab
536821ab
376821ab
668821ab
4d8821ab
26c821ab
(9 rows)
Time: 0.506 ms
带后缀的模糊查询，使用索引只需要0.5毫秒。
可以使用pg_trgm的gin索引，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
postgres=# create extension pg_trgm;
postgres=# explain select * from tb where info ~ '5821a';
QUERY PLAN
----------------------------------------------------------------------------
Bitmap Heap Scan on tb (cost=103.75..3677.71 rows=1000 width=9)
Recheck Cond: (info ~ '5821a'::text)
-> Bitmap Index Scan on idx_tb_2 (cost=0.00..103.50 rows=1000 width=0)
Index Cond: (info ~ '5821a'::text)
(4 rows)
Time: 0.647 ms
postgres=# select * from tb where info ~ '5821a';
info
----------
5821a8a3
945821af
45821a74
9fe5821a
5821a7e0
5821af2a
1075821a
e5821ac9
d265821a
45f5821a
df5821a4
de5821af
71c5821a
375821a3
fc5821af
5c5821ad
e65821ab
5821adde
c35821a6
5821a642
305821ab
5821a1c8
75821a5c
ce95821a
a65821ad
(25 rows)
Time: 3.808 ms
前后模糊查询，使用索引只需要3.8毫秒。
可以使用pg_trgm的gin索引，或者拆列用多列索引叠加bit and或bit or进行优化（只适合固定长度的端字符串，例如char(8)）。
前后模糊查询，使用索引只需要108毫秒。
postgres=# select * from tb where info ~ 'e65[\d]{2}a[b]{1,2}8' limit 10;
info
----------
4e6567ab
1e6530ab
e6500ab8
ae6583ab
e6564ab7
5e6532ab
e6526abf
e6560ab6
(8 rows)
Time: 108.577 ms
时间主要花费在排他上面。
检索了14794行，remove了14793行。大量的时间花费在无用功上，但是比全表扫还是好很多。
postgres=# explain (verbose,analyze,buffers,costs,timing) select * from tb where info ~ 'e65[\d]{2}a[b]{1,2}8' limit 10;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------
Limit (cost=511.75..547.49 rows=10 width=9) (actual time=89.934..120.567 rows=1 loops=1)
Output: info
Buffers: shared hit=13054
-> Bitmap Heap Scan on public.tb (cost=511.75..4085.71 rows=1000 width=9) (actual time=89.930..120.562 rows=1 loops=1)
Output: info
Recheck Cond: (tb.info ~ 'e65[\d]{2}a[b]{1,2}8'::text)
Rows Removed by Index Recheck: 14793
Heap Blocks: exact=12929
Buffers: shared hit=13054
-> Bitmap Index Scan on idx_tb_2 (cost=0.00..511.50 rows=1000 width=0) (actual time=67.589..67.589 rows=14794 loops=1)
Index Cond: (tb.info ~ 'e65[\d]{2}a[b]{1,2}8'::text)
Buffers: shared hit=125
Planning time: 0.493 ms
Execution time: 120.618 ms
(14 rows)
Time: 124.693 ms
优化：
使用gin索引后，需要考虑性能问题，因为info字段被打散成了多个char(3)的token，从而涉及到非常多的索引条目，如果有非常高并发的插入，最好把gin_pending_list_limit设大，来提高插入效率，降低实时合并索引带来的RT升高。
使用了fastupdate后，会在每次vacuum表时，自动将pengding的信息合并到GIN索引中。
还有一点，查询不会有合并的动作，对于没有合并的GIN信息是使用遍历的方式搜索的。
create table tbl(id serial8, crt_time timestamp, sensorid int, sensorloc point, info text) with (autovacuum_enabled=on, autovacuum_vacuum_threshold=0.000001,autovacuum_vacuum_cost_delay=0);
CREATE INDEX trgm_idx ON tbl USING GIN (info gin_trgm_ops) with (fastupdate='on', gin_pending_list_limit='6553600');
alter sequence tbl_id_seq cache 10000;
修改配置，让数据库的autovacuum快速迭代合并gin。
vi $PGDATA/postgresql.conf
autovacuum_naptime=30s
maintenance_work_mem=1GB
autovacuum_work_mem=1GB
autovacuum = on
autovacuum_max_workers = 3
log_autovacuum_min_duration = 0
autovacuum_vacuum_cost_delay=0
$ pg_ctl reload
创建一个测试函数，用来产生随机的测试数据。
postgres=# create or replace function f() returns void as $$
insert into tbl (crt_time,sensorid,info) values ( clock_timestamp(),trunc(random()*500000),substring(md5(random()::text),1,8) );
$$ language sql strict;
vi test.sql
select f();
pgbench -M prepared -n -r -P 1 -f ./test.sql -c 48 -j 48 -T 10000
progress: 50.0 s, 52800.9 tps, lat 0.453 ms stddev 0.390
progress: 51.0 s, 52775.8 tps, lat 0.453 ms stddev 0.398
progress: 52.0 s, 53173.2 tps, lat 0.449 ms stddev 0.371
progress: 53.0 s, 53010.0 tps, lat 0.451 ms stddev 0.390
progress: 54.0 s, 53360.9 tps, lat 0.448 ms stddev 0.365
progress: 55.0 s, 53285.0 tps, lat 0.449 ms stddev 0.362
progress: 56.0 s, 53662.1 tps, lat 0.445 ms stddev 0.368
progress: 57.0 s, 53283.8 tps, lat 0.448 ms stddev 0.385
progress: 58.0 s, 53703.4 tps, lat 0.445 ms stddev 0.355
progress: 59.0 s, 53818.7 tps, lat 0.444 ms stddev 0.344
progress: 60.0 s, 53889.2 tps, lat 0.443 ms stddev 0.361
progress: 61.0 s, 53613.8 tps, lat 0.446 ms stddev 0.355
progress: 62.0 s, 53339.9 tps, lat 0.448 ms stddev 0.392
progress: 63.0 s, 54014.9 tps, lat 0.442 ms stddev 0.346
progress: 64.0 s, 53112.1 tps, lat 0.450 ms stddev 0.374
progress: 65.0 s, 53706.1 tps, lat 0.445 ms stddev 0.367
progress: 66.0 s, 53720.9 tps, lat 0.445 ms stddev 0.353
progress: 67.0 s, 52858.1 tps, lat 0.452 ms stddev 0.415
progress: 68.0 s, 53218.9 tps, lat 0.449 ms stddev 0.387
progress: 69.0 s, 53403.0 tps, lat 0.447 ms stddev 0.377
progress: 70.0 s, 53179.9 tps, lat 0.449 ms stddev 0.377
progress: 71.0 s, 53232.4 tps, lat 0.449 ms stddev 0.373
progress: 72.0 s, 53011.7 tps, lat 0.451 ms stddev 0.386
progress: 73.0 s, 52685.1 tps, lat 0.454 ms stddev 0.384
progress: 74.0 s, 52937.8 tps, lat 0.452 ms stddev 0.377
按照这个速度，一天能支持超过40亿数据入库。
接下来对比一下字符串分离的例子，这个例子适用于字符串长度固定，并且很小的场景，如果字符串长度不固定，这种方法没用。
适用splict的方法，测试数据不尽人意，所以还是用pg_trgm比较靠谱。
postgres=# create table t_split(id int, crt_time timestamp, sensorid int, sensorloc point, info text, c1 char(1), c2 char(1), c3 char(1), c4 char(1), c5 char(1), c6 char(1), c7 char(1), c8 char(1));
CREATE TABLE
Time: 2.123 ms
postgres=# insert into t_split(id,crt_time,sensorid,info,c1,c2,c3,c4,c5,c6,c7,c8) select id,ct,sen,info,substring(info,1,1),substring(info,2,1),substring(info,3,1),substring(info,4,1),substring(info,5,1),substring(info,6,1),substring(info,7,1),substring(info,8,1) from (select id, clock_timestamp() ct, trunc(random()*500000) sen, substring(md5(random()::text), 1, 8) info from generate_series(1,10000000) t(id)) t;
INSERT 0 10000000
Time: 81829.274 ms
postgres=# create index idx1 on t_split (c1);
postgres=# create index idx2 on t_split (c2);
postgres=# create index idx3 on t_split (c3);
postgres=# create index idx4 on t_split (c4);
postgres=# create index idx5 on t_split (c5);
postgres=# create index idx6 on t_split (c6);
postgres=# create index idx7 on t_split (c7);
postgres=# create index idx8 on t_split (c8);
postgres=# create index idx9 on t_split using gin (info gin_trgm_ops);
postgres=# select * from t_split limit 1;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
(1 row)
postgres=# select * from t_split where info ~ '^3[\d]?eed[\d]?79$' limit 10;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
(1 row)
Time: 133.041 ms
postgres=# explain (analyze,verbose,timing,costs,buffers) select * from t_split where info ~ '^3[\d]?eed[\d]?79$' limit 10;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------
Limit (cost=575.75..612.78 rows=10 width=57) (actual time=92.406..129.838 rows=1 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Buffers: shared hit=13798
-> Bitmap Heap Scan on public.t_split (cost=575.75..4278.56 rows=1000 width=57) (actual time=92.403..129.833 rows=1 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Recheck Cond: (t_split.info ~ '^3[\d]?eed[\d]?79$'::text)
Rows Removed by Index Recheck: 14690
Heap Blocks: exact=13669
Buffers: shared hit=13798
-> Bitmap Index Scan on idx9 (cost=0.00..575.50 rows=1000 width=0) (actual time=89.576..89.576 rows=14691 loops=1)
Index Cond: (t_split.info ~ '^3[\d]?eed[\d]?79$'::text)
Buffers: shared hit=129
Planning time: 0.385 ms
Execution time: 129.883 ms
(14 rows)
Time: 130.678 ms
postgres=# select * from t_split where c1='3' and c3='e' and c4='e' and c5='d' and c7='7' and c8='9' and c2 between '0' and '9' and c6 between '0' and '9' limit 10;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
(1 row)
Time: 337.367 ms
postgres=# explain (analyze,verbose,timing,costs,buffers) select * from t_split where c1='3' and c3='e' and c4='e' and c5='d' and c7='7' and c8='9' and c2 between '0' and '9' and c6 between '0' and '9' limit 10;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=33582.31..41499.35 rows=1 width=57) (actual time=339.230..344.675 rows=1 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Buffers: shared hit=7581
-> Bitmap Heap Scan on public.t_split (cost=33582.31..41499.35 rows=1 width=57) (actual time=339.228..344.673 rows=1 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Recheck Cond: ((t_split.c3 = 'e'::bpchar) AND (t_split.c8 = '9'::bpchar) AND (t_split.c5 = 'd'::bpchar))
Filter: ((t_split.c2 >= '0'::bpchar) AND (t_split.c2 <= '9'::bpchar) AND (t_split.c6 >= '0'::bpchar) AND (t_split.c6 <= '9'::bpchar) AND (t_split.c1 = '3'::bpchar) AND (t_split.c4 = 'e'::bpchar) AND (t_split.c7 = '7'::bpchar))
Rows Removed by Filter: 2480
Heap Blocks: exact=2450
Buffers: shared hit=7581
-> BitmapAnd (cost=33582.31..33582.31 rows=2224 width=0) (actual time=338.512..338.512 rows=0 loops=1)
Buffers: shared hit=5131
-> Bitmap Index Scan on idx3 (cost=0.00..11016.93 rows=596333 width=0) (actual time=104.418..104.418 rows=624930 loops=1)
Index Cond: (t_split.c3 = 'e'::bpchar)
Buffers: shared hit=1711
-> Bitmap Index Scan on idx8 (cost=0.00..11245.44 rows=608667 width=0) (actual time=100.185..100.185 rows=625739 loops=1)
Index Cond: (t_split.c8 = '9'::bpchar)
Buffers: shared hit=1712
-> Bitmap Index Scan on idx5 (cost=0.00..11319.44 rows=612667 width=0) (actual time=99.480..99.480 rows=624269 loops=1)
Index Cond: (t_split.c5 = 'd'::bpchar)
Buffers: shared hit=1708
Planning time: 0.262 ms
Execution time: 344.731 ms
(23 rows)
Time: 346.424 ms
postgres=# select * from t_split where info ~ '^33.+7.+9$' limit 10;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
--------+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
24412 | 2016-03-02 09:58:04.186359 | 251599 | | 33f07429 | 3 | 3 | f | 0 | 7 | 4 | 2 | 9
24989 | 2016-03-02 09:58:04.191112 | 214569 | | 334587d9 | 3 | 3 | 4 | 5 | 8 | 7 | d | 9
50100 | 2016-03-02 09:58:04.398499 | 409819 | | 33beb7b9 | 3 | 3 | b | e | b | 7 | b | 9
92623 | 2016-03-02 09:58:04.745372 | 280100 | | 3373e719 | 3 | 3 | 7 | 3 | e | 7 | 1 | 9
106054 | 2016-03-02 09:58:04.855627 | 155192 | | 33c575c9 | 3 | 3 | c | 5 | 7 | 5 | c | 9
107070 | 2016-03-02 09:58:04.863827 | 464325 | | 337dd729 | 3 | 3 | 7 | d | d | 7 | 2 | 9
135152 | 2016-03-02 09:58:05.088217 | 240500 | | 336271d9 | 3 | 3 | 6 | 2 | 7 | 1 | d | 9
156425 | 2016-03-02 09:58:05.25805 | 218202 | | 333e7289 | 3 | 3 | 3 | e | 7 | 2 | 8 | 9
170210 | 2016-03-02 09:58:05.368371 | 132530 | | 33a8d789 | 3 | 3 | a | 8 | d | 7 | 8 | 9
(10 rows)
Time: 20.431 ms
postgres=# explain (analyze,verbose,timing,costs,buffers) select * from t_split where info ~ '^33.+7.+9$' limit 10;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------
Limit (cost=43.75..80.78 rows=10 width=57) (actual time=19.573..21.212 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Buffers: shared hit=566
-> Bitmap Heap Scan on public.t_split (cost=43.75..3746.56 rows=1000 width=57) (actual time=19.571..21.206 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Recheck Cond: (t_split.info ~ '^33.+7.+9$'::text)
Rows Removed by Index Recheck: 647
Heap Blocks: exact=552
Buffers: shared hit=566
-> Bitmap Index Scan on idx9 (cost=0.00..43.50 rows=1000 width=0) (actual time=11.712..11.712 rows=39436 loops=1)
Index Cond: (t_split.info ~ '^33.+7.+9$'::text)
Buffers: shared hit=14
Planning time: 0.301 ms
Execution time: 21.255 ms
(14 rows)
Time: 21.995 ms
postgres=# select * from t_split where c1='3' and c2='3' and c8='9' and (c4='7' or c5='7' or c6='7') limit 10;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
--------+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
24412 | 2016-03-02 09:58:04.186359 | 251599 | | 33f07429 | 3 | 3 | f | 0 | 7 | 4 | 2 | 9
24989 | 2016-03-02 09:58:04.191112 | 214569 | | 334587d9 | 3 | 3 | 4 | 5 | 8 | 7 | d | 9
50100 | 2016-03-02 09:58:04.398499 | 409819 | | 33beb7b9 | 3 | 3 | b | e | b | 7 | b | 9
92623 | 2016-03-02 09:58:04.745372 | 280100 | | 3373e719 | 3 | 3 | 7 | 3 | e | 7 | 1 | 9
106054 | 2016-03-02 09:58:04.855627 | 155192 | | 33c575c9 | 3 | 3 | c | 5 | 7 | 5 | c | 9
107070 | 2016-03-02 09:58:04.863827 | 464325 | | 337dd729 | 3 | 3 | 7 | d | d | 7 | 2 | 9
135152 | 2016-03-02 09:58:05.088217 | 240500 | | 336271d9 | 3 | 3 | 6 | 2 | 7 | 1 | d | 9
156425 | 2016-03-02 09:58:05.25805 | 218202 | | 333e7289 | 3 | 3 | 3 | e | 7 | 2 | 8 | 9
170210 | 2016-03-02 09:58:05.368371 | 132530 | | 33a8d789 | 3 | 3 | a | 8 | d | 7 | 8 | 9
(10 rows)
Time: 37.739 ms
postgres=# explain (analyze,verbose,timing,costs,buffers) select * from t_split where c1='3' and c2='3' and c8='9' and (c4='7' or c5='7' or c6='7') limit 10;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=0.00..8135.78 rows=10 width=57) (actual time=0.017..35.532 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Buffers: shared hit=1755
-> Seq Scan on public.t_split (cost=0.00..353093.00 rows=434 width=57) (actual time=0.015..35.526 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8
Filter: ((t_split.c1 = '3'::bpchar) AND (t_split.c2 = '3'::bpchar) AND (t_split.c8 = '9'::bpchar) AND ((t_split.c4 = '7'::bpchar) OR (t_split.c5 = '7'::bpchar) OR (t_split.c6 = '7'::bpchar)))
Rows Removed by Filter: 170200
Buffers: shared hit=1755
Planning time: 0.210 ms
Execution time: 35.572 ms
(10 rows)
Time: 36.260 ms
postgres=# select * from t_split where info ~ '^3.?[b-g]+ed[\d]+79' order by info <-> '^3.?[b-g]+ed[\d]+79' limit 10;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
---------+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
1308724 | 2016-03-02 09:58:14.590901 | 458822 | | 3fed9479 | 3 | f | e | d | 9 | 4 | 7 | 9
2866024 | 2016-03-02 09:58:27.20105 | 106467 | | 3fed2279 | 3 | f | e | d | 2 | 2 | 7 | 9
4826729 | 2016-03-02 09:58:42.907431 | 228023 | | 3ded9879 | 3 | d | e | d | 9 | 8 | 7 | 9
6113373 | 2016-03-02 09:58:53.211146 | 499702 | | 36fed479 | 3 | 6 | f | e | d | 4 | 7 | 9
1768237 | 2016-03-02 09:58:18.310069 | 345027 | | 30fed079 | 3 | 0 | f | e | d | 0 | 7 | 9
1472324 | 2016-03-02 09:58:15.913629 | 413283 | | 3eed5798 | 3 | e | e | d | 5 | 7 | 9 | 8
8319056 | 2016-03-02 09:59:10.902137 | 336740 | | 3ded7790 | 3 | d | e | d | 7 | 7 | 9 | 0
8576573 | 2016-03-02 09:59:12.962923 | 130223 | | 3eed5793 | 3 | e | e | d | 5 | 7 | 9 | 3
(9 rows)
Time: 268.661 ms
postgres=# explain (analyze,verbose,timing,buffers,costs) select * from t_split where info ~ '^3.?[b-g]+ed[\d]+79' order by info <-> '^3.?[b-g]+ed[\d]+79' limit 10;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=4302.66..4302.69 rows=10 width=57) (actual time=269.214..269.217 rows=9 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8, ((info <-> '^3.?[b-g]+ed[\d]+79'::text))
Buffers: shared hit=52606
-> Sort (cost=4302.66..4305.16 rows=1000 width=57) (actual time=269.212..269.212 rows=9 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8, ((info <-> '^3.?[b-g]+ed[\d]+79'::text))
Sort Key: ((t_split.info <-> '^3.?[b-g]+ed[\d]+79'::text))
Sort Method: quicksort Memory: 26kB
Buffers: shared hit=52606
-> Bitmap Heap Scan on public.t_split (cost=575.75..4281.06 rows=1000 width=57) (actual time=100.771..269.180 rows=9 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8, (info <-> '^3.?[b-g]+ed[\d]+79'::text)
Recheck Cond: (t_split.info ~ '^3.?[b-g]+ed[\d]+79'::text)
Rows Removed by Index Recheck: 72929
Heap Blocks: exact=52479
Buffers: shared hit=52606
-> Bitmap Index Scan on idx9 (cost=0.00..575.50 rows=1000 width=0) (actual time=88.062..88.062 rows=72938 loops=1)
Index Cond: (t_split.info ~ '^3.?[b-g]+ed[\d]+79'::text)
Buffers: shared hit=127
Planning time: 0.640 ms
Execution time: 269.287 ms
(19 rows)
Time: 270.430 ms
postgres=# select * from t_split where info ~ '3.?[b-g]+ed[\d]+79' order by info <-> '3.?[b-g]+ed[\d]+79' limit 10;
id | crt_time | sensorid | sensorloc | info | c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
---------+----------------------------+----------+-----------+----------+----+----+----+----+----+----+----+----
1 | 2016-03-02 09:58:03.990639 | 161958 | | 33eed779 | 3 | 3 | e | e | d | 7 | 7 | 9
1308724 | 2016-03-02 09:58:14.590901 | 458822 | | 3fed9479 | 3 | f | e | d | 9 | 4 | 7 | 9
4826729 | 2016-03-02 09:58:42.907431 | 228023 | | 3ded9879 | 3 | d | e | d | 9 | 8 | 7 | 9
5250603 | 2016-03-02 09:58:46.300289 | 250582 | | d3eed179 | d | 3 | e | e | d | 1 | 7 | 9
6113373 | 2016-03-02 09:58:53.211146 | 499702 | | 36fed479 | 3 | 6 | f | e | d | 4 | 7 | 9
1768237 | 2016-03-02 09:58:18.310069 | 345027 | | 30fed079 | 3 | 0 | f | e | d | 0 | 7 | 9
2866024 | 2016-03-02 09:58:27.20105 | 106467 | | 3fed2279 | 3 | f | e | d | 2 | 2 | 7 | 9
1472324 | 2016-03-02 09:58:15.913629 | 413283 | | 3eed5798 | 3 | e | e | d | 5 | 7 | 9 | 8
8576573 | 2016-03-02 09:59:12.962923 | 130223 | | 3eed5793 | 3 | e | e | d | 5 | 7 | 9 | 3
8319056 | 2016-03-02 09:59:10.902137 | 336740 | | 3ded7790 | 3 | d | e | d | 7 | 7 | 9 | 0
(10 rows)
Time: 320.525 ms
postgres=# explain (analyze,verbose,buffers,costs,timing) select * from t_split where info ~ '3.?[b-g]+ed[\d]+79' order by info <-> '3.?[b-g]+ed[\d]+79' limit 10;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=4302.66..4302.69 rows=10 width=57) (actual time=319.925..319.927 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8, ((info <-> '3.?[b-g]+ed[\d]+79'::text))
Buffers: shared hit=52602
-> Sort (cost=4302.66..4305.16 rows=1000 width=57) (actual time=319.923..319.923 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8, ((info <-> '3.?[b-g]+ed[\d]+79'::text))
Sort Key: ((t_split.info <-> '3.?[b-g]+ed[\d]+79'::text))
Sort Method: quicksort Memory: 26kB
Buffers: shared hit=52602
-> Bitmap Heap Scan on public.t_split (cost=575.75..4281.06 rows=1000 width=57) (actual time=104.526..319.885 rows=10 loops=1)
Output: id, crt_time, sensorid, sensorloc, info, c1, c2, c3, c4, c5, c6, c7, c8, (info <-> '3.?[b-g]+ed[\d]+79'::text)
Recheck Cond: (t_split.info ~ '3.?[b-g]+ed[\d]+79'::text)
Rows Removed by Index Recheck: 72928
Heap Blocks: exact=52479
Buffers: shared hit=52602
-> Bitmap Index Scan on idx9 (cost=0.00..575.50 rows=1000 width=0) (actual time=91.945..91.945 rows=72938 loops=1)
Index Cond: (t_split.info ~ '3.?[b-g]+ed[\d]+79'::text)
Buffers: shared hit=123
Planning time: 0.948 ms
Execution time: 320.003 ms
(19 rows)
Time: 321.502 ms
模拟分区表，每小时一个分区，每小时数据量5000万，一天12亿，一个月360亿。
drop table tbl cascade;
create table tbl (id serial8, crt_time timestamp, sensorid int, sensorloc point, info text);
do language plpgsql $$
declare
v_s timestamp := '2016-01-01 00:00:00';
begin
for i in 1..720 loop
execute 'create table tbl_'||to_char(v_s,'yyyymmddhh24')||' (id int8 not null default nextval(''tbl_id_seq''::regclass), crt_time timestamp check (crt_time >= '''||to_char(v_s,'yyyy-mm-dd hh24:mi:ss')||''' and crt_time <'''||to_char(v_s+'1 h'::interval,'yyyy-mm-dd hh24:mi:ss')||'''), sensorid int, sensorloc point, info text) inherits (tbl)';
v_s := v_s + '1 h'::interval;
end loop;
end;
$$;
alter sequence tbl_id_seq cache 100000;
生成插入SQL
do language plpgsql $$
declare
v_s timestamp := '2016-01-01 00:00:00';
begin
for i in 1..720 loop
raise notice '%', 'psql -c "insert into tbl_'||to_char(v_s,'yyyymmddhh24')||' (crt_time, sensorid, info) select '''||to_char(v_s,'yyyy-mm-dd hh24:mi:ss')||''',trunc(random()*500000), substring(md5(random()::text),1,8) from generate_series(1,50000000);" &';
v_s := v_s + '1 h'::interval;
end loop;
end;
$$;
性能指标, 范围扫描, 落到单表5000万的数据量内, 毫秒级返回.
postgres=# explain (analyze,verbose,timing,buffers,costs) select * from tbl where crt_time between '2016-01-01 12:00:00' and '2016-01-01 12:30:00' and info ~ 'f[\d]{2}e27e0$' order by info <-> 'f[\d]{2}e27e0$' limit 10;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=18918.83..18918.85 rows=10 width=45) (actual time=350.296..350.297 rows=2 loops=1)
Output: tbl.id, tbl.crt_time, tbl.sensorid, tbl.sensorloc, tbl.info, ((tbl.info <-> 'f[\d]{2}e27e0$'::text))
Buffers: shared hit=4530
-> Sort (cost=18918.83..18931.33 rows=5001 width=45) (actual time=350.294..350.295 rows=2 loops=1)
Output: tbl.id, tbl.crt_time, tbl.sensorid, tbl.sensorloc, tbl.info, ((tbl.info <-> 'f[\d]{2}e27e0$'::text))
Sort Key: ((tbl.info <-> 'f[\d]{2}e27e0$'::text))
Sort Method: quicksort Memory: 25kB
Buffers: shared hit=4530
-> Result (cost=0.00..18810.76 rows=5001 width=45) (actual time=347.995..350.279 rows=2 loops=1)
Output: tbl.id, tbl.crt_time, tbl.sensorid, tbl.sensorloc, tbl.info, (tbl.info <-> 'f[\d]{2}e27e0$'::text)
Buffers: shared hit=4530
-> Append (cost=0.00..18798.26 rows=5001 width=45) (actual time=347.976..350.254 rows=2 loops=1)
Buffers: shared hit=4530
-> Seq Scan on public.tbl (cost=0.00..0.00 rows=1 width=68) (actual time=0.001..0.001 rows=0 loops=1)
Output: tbl.id, tbl.crt_time, tbl.sensorid, tbl.sensorloc, tbl.info
Filter: ((tbl.crt_time >= '2016-01-01 12:00:00'::timestamp without time zone) AND (tbl.crt_time <= '2016-01-01 12:30:00'::timestamp without time zone) AND (tbl.info ~ 'f[\d]{2}e27e0$'::text))
-> Bitmap Heap Scan on public.tbl_2016010112 (cost=574.75..18798.26 rows=5000 width=45) (actual time=347.972..350.249 rows=2 loops=1)
Output: tbl_2016010112.id, tbl_2016010112.crt_time, tbl_2016010112.sensorid, tbl_2016010112.sensorloc, tbl_2016010112.info
Recheck Cond: (tbl_2016010112.info ~ 'f[\d]{2}e27e0$'::text)
Rows Removed by Index Recheck: 4100
Filter: ((tbl_2016010112.crt_time >= '2016-01-01 12:00:00'::timestamp without time zone) AND (tbl_2016010112.crt_time <= '2016-01-01 12:30:00'::timestamp without time zone))
Heap Blocks: exact=4085
Buffers: shared hit=4530
-> Bitmap Index Scan on idx_tbl_2016010112 (cost=0.00..573.50 rows=5000 width=0) (actual time=337.125..337.125 rows=4102 loops=1)
Index Cond: (tbl_2016010112.info ~ 'f[\d]{2}e27e0$'::text)
Buffers: shared hit=445
Planning time: 23.913 ms
Execution time: 350.383 ms
(28 rows)
postgres=# select * from tbl where crt_time between '2016-01-01 12:00:00' and '2016-01-01 12:30:00' and info ~ 'f[\d]{2}e27e0$' order by info <-> 'f[\d]{2}e27e0$' limit 10;
id | crt_time | sensorid | sensorloc | info
------------+---------------------+----------+-----------+----------
1982100172 | 2016-01-01 12:00:00 | 336772 | | f48e27e0
2292713691 | 2016-01-01 12:00:00 | 489110 | | f77e27e0
(2 rows)
postgres=# \dt+ t_all
List of relations
Schema | Name | Type | Owner | Size | Description
--------+-------+-------+----------+--------+-------------
public | t_all | table | postgres | 811 GB |
(1 row)
postgres=# \d t_all
Table "public.t_all"
Column | Type | Modifiers
-----------+-----------------------------+-----------
id | bigint | not null
crt_time | timestamp without time zone |
sensorid | integer |
sensorloc | point |
info | text |
postgres=# select count(*) from t_all;
count
-------------
14456717312
(1 row)
postgres=# select * from t_all limit 10;
id | crt_time | sensorid | sensorloc | info
------------+---------------------+----------+-----------+----------
6519272065 | 2016-01-06 10:00:00 | 493013 | | 62255c83
6519272066 | 2016-01-06 10:00:00 | 309676 | | f6c98800
6519272067 | 2016-01-06 10:00:00 | 43859 | | 125a1191
6519272068 | 2016-01-06 10:00:00 | 495624 | | e75cfd71
6519272069 | 2016-01-06 10:00:00 | 10362 | | 7171f11c
6519272070 | 2016-01-06 10:00:00 | 231476 | | 4201f809
6519272071 | 2016-01-06 10:00:00 | 43080 | | a47e84e5
6519272072 | 2016-01-06 10:00:00 | 131292 | | 17bc248e
6519272073 | 2016-01-06 10:00:00 | 486841 | | 3303097c
6519272074 | 2016-01-06 10:00:00 | 491503 | | f0c53fee
(10 rows)
测试数据后续放出，分表后做到秒级是没有问题的。信心从何而来呢？
因为瓶颈不在IO上，主要在数据的recheck, 把144亿数据拆分成29个5亿的表，并行执行，秒出是有可能的。
来看一个单表5亿的测试结果，秒出：
postgres=# explain (verbose,analyze,buffers,timing,costs) select * from tbl1 where info ~ 'aad.+f02' limit 10;
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=1439.79..1476.19 rows=10 width=29) (actual time=116.570..116.719 rows=10 loops=1)
Output: id, crt_time, sensorid, info
Buffers: shared hit=680
-> Bitmap Heap Scan on public.tbl1 (cost=1439.79..191054.88 rows=52103 width=29) (actual time=116.568..116.716 rows=10 loops=1)
Output: id, crt_time, sensorid, info
Recheck Cond: (tbl1.info ~ 'aad.+f02'::text)
Rows Removed by Index Recheck: 38
Heap Blocks: exact=48
Buffers: shared hit=680
-> Bitmap Index Scan on tbl1_info_idx (cost=0.00..1426.77 rows=52103 width=0) (actual time=116.495..116.495 rows=403 loops=1)
Index Cond: (tbl1.info ~ 'aad.+f02'::text)
Buffers: shared hit=632
Planning time: 0.311 ms
Execution time: 116.754 ms
(14 rows)
Time: 117.422 ms
postgres=# select * from tbl1 where info ~ 'aad.+f02' limit 10;
id | crt_time | sensorid | info
-----------+----------------------------+----------+----------
17986922 | 2016-02-29 17:42:42.427639 | 75863 | aad3f02a
19873247 | 2016-02-29 17:43:16.714945 | 174971 | 2aad5f02
23798336 | 2016-02-29 17:44:35.369654 | 202085 | aad06f02
28630866 | 2016-02-29 17:46:03.544462 | 463184 | baad3f02
31458529 | 2016-02-29 17:47:00.300937 | 411670 | aad1af02
52009687 | 2016-02-29 17:53:15.466246 | 192821 | 5aad6f02
80769909 | 2016-02-29 18:01:31.074248 | 47993 | aadcf029
80825896 | 2016-02-29 18:01:31.039063 | 284712 | aad14f02
83385996 | 2016-02-29 18:02:12.699317 | 78233 | daadcf02
102814316 | 2016-02-29 18:08:20.891412 | 359635 | aad06f02
(10 rows)
Time: 116.901 ms
全表扫描需要,
postgres=# set enable_bitmapscan=off;
SET
Time: 0.145 ms
postgres=# select * from tbl1 where info ~ 'aad.+f02' limit 10;
id | crt_time | sensorid | info
-----------+----------------------------+----------+----------
31458529 | 2016-02-29 17:47:00.300937 | 411670 | aad1af02
52009687 | 2016-02-29 17:53:15.466246 | 192821 | 5aad6f02
80769909 | 2016-02-29 18:01:31.074248 | 47993 | aadcf029
80825896 | 2016-02-29 18:01:31.039063 | 284712 | aad14f02
83385996 | 2016-02-29 18:02:12.699317 | 78233 | daadcf02
102814316 | 2016-02-29 18:08:20.891412 | 359635 | aad06f02
105236847 | 2016-02-29 18:09:56.914795 | 876 | aadbf026
108524272 | 2016-02-29 18:10:47.39312 | 338071 | 2aad2f02
128169786 | 2016-02-29 18:17:52.105948 | 262400 | aad0f028
135935810 | 2016-02-29 18:20:43.265139 | 487673 | aad7f021
(10 rows)
Time: 98903.073 ms
1000万数据对比
5亿数据对比
1000万数据btree bit or|and与gin对比
144亿分区表对比
大数据量的优化方法，例如百亿级别以上的数据量，如何能做到秒级的模糊查询响应。
对于单机，可以使用分区，同时使用并行查询，充分使用CPU的功能。
或者使用MPP, SHARDING架构，利用多机的资源。
原则，减少recheck，尽量扫描搜索到最终需要的结果（大量扫描，大量remove checked false row, 全表和索引都存在这种现象）
1. 测试用的主机配置简单描述
普通x86, 24核，1xxG 内存，SSD硬盘。
2. 收到了一位朋友的疑问，
德哥,首先要问你一个问题, 为什么你使用md5 前8位生成 数据 ? md5 最小位数就是16位 , 你这样做究竟有什么数学原因导致要前8位字符?
回复如下：
首先MD5计算的结果是一个128bit的hex，PostgreSQL将结果以文本的形式输出，所以看到的是32位长度的字符串，
rfc1321
3.1 Step 1. Append Padding Bits
3.2 Step 2. Append Length
3.3 Step 3. Initialize MD Buffer
3.4 Step 4. Process Message in 16-Word Blocks
3.5 Step 5. Output
4. Summary
The MD5 message-digest algorithm is simple to implement, and provides
a "fingerprint" or message digest of a message of arbitrary length.
It is conjectured that the difficulty of coming up with two messages
having the same message digest is on the order of 2^64 operations,
and that the difficulty of coming up with any message having a given
message digest is on the order of 2^128 operations. The MD5 algorithm
has been carefully scrutinized for weaknesses. It is, however, a
relatively new algorithm and further security analysis is of course
justified, as is the case with any new proposal of this sort.
PG代码
/*
* Create an md5 hash of a text string and return it as hex
*
* md5 produces a 16 byte (128 bit) hash; double it for hex
*/
#define MD5_HASH_LEN 32
Datum
md5_text(PG_FUNCTION_ARGS)
{
text *in_text = PG_GETARG_TEXT_PP(0);
size_t len;
char hexsum[MD5_HASH_LEN + 1];
/* Calculate the length of the buffer using varlena metadata */
len = VARSIZE_ANY_EXHDR(in_text);
/* get the hash result */
if (pg_md5_hash(VARDATA_ANY(in_text), len, hexsum) == false)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
/* convert to text and return it */
PG_RETURN_TEXT_P(cstring_to_text(hexsum));
}
/*
* pg_md5_hash
*
* Calculates the MD5 sum of the bytes in a buffer.
*
* SYNOPSIS #include "md5.h"
* int pg_md5_hash(const void *buff, size_t len, char *hexsum)
*
* INPUT buff the buffer containing the bytes that you want
* the MD5 sum of.
* len number of bytes in the buffer.
*
* OUTPUT hexsum the MD5 sum as a '\0'-terminated string of
* hexadecimal digits. an MD5 sum is 16 bytes long.
* each byte is represented by two heaxadecimal
* characters. you thus need to provide an array
* of 33 characters, including the trailing '\0'.
*
* RETURNS false on failure (out of memory for internal buffers) or
* true on success.
*
* STANDARDS MD5 is described in RFC 1321.
*
* AUTHOR Sverre H. Huseby <sverrehu@online.no>
*
*/
bool
pg_md5_hash(const void *buff, size_t len, char *hexsum)
{
uint8 sum[16];
if (!calculateDigestFromBuffer(buff, len, sum))
return false;
bytesToHex(sum, hexsum);
return true;
}
static int
calculateDigestFromBuffer(const uint8 *b, uint32 len, uint8 sum[16])
{
register uint32 i,
j,
k,
newI;
uint32 l;
uint8 *input;
register uint32 *wbp;
uint32 workBuff[16],
state[4];
l = len;
state[0] = 0x67452301;
state[1] = 0xEFCDAB89;
state[2] = 0x98BADCFE;
state[3] = 0x10325476;
if ((input = createPaddedCopyWithLength(b, &l)) == NULL)
return 0;
for (i = 0;;)
{
if ((newI = i + 16 * 4) > l)
break;
k = i + 3;
for (j = 0; j < 16; j++)
{
wbp = (workBuff + j);
*wbp = input[k--];
*wbp <<= 8;
*wbp |= input[k--];
*wbp <<= 8;
*wbp |= input[k--];
*wbp <<= 8;
*wbp |= input[k];
k += 7;
}
doTheRounds(workBuff, state);
i = newI;
}
free(input);
j = 0;
for (i = 0; i < 4; i++)
{
k = state[i];
sum[j++] = (k & 0xff);
k >>= 8;
sum[j++] = (k & 0xff);
k >>= 8;
sum[j++] = (k & 0xff);
k >>= 8;
sum[j++] = (k & 0xff);
}
return 1;
}
postgres=# select length(md5(random()::text)),md5(random()::text) from generate_series(1,10);
length | md5
--------+----------------------------------
32 | 4b0fcafd0f9d189cceade2812e4aa396
32 | 9169f49f0c059a65de3325a20068eb8e
32 | 7df4b60638972f1372fde91e3d2eee50
32 | 4fc6816aa88224163dda3e242f3e16f0
32 | 518870a2c8a9cfe6cba018916f5388a9
32 | b46b63c409532e5c973ddc27a5e49ce4
32 | e24e9d63926094046aa2b300dfa8e986
32 | 3f1ca7c5ce5159a0df17729f81e24925
32 | 5756f0925eca4c3801c4a49cf9b68023
32 | ed54795fcbe9491f4e5a00ec2cf323ee
(10 rows)
另外，截取前8位的目的是生成一个8位长的随机字符串，在车牌，QQ，条形码等数据类型中长度的一个折中。
其实要测试16或32位长的随机字符串也可以的，我稍后更新一下对应长度的测试数据。
高并发的优化
http://blog.163.com/digoal@126/blog/static/16387704020159853541614/
秒杀性能调优
http://blog.163.com/digoal@126/blog/static/16387704020158149538415/
每天万亿级记录流式处理
http://blog.163.com/digoal@126/blog/static/1638770402015111543639382/
百亿级数据量地理位置检索
http://blog.163.com/digoal@126/blog/static/163877040201601875129497/
水平分片
http://blog.163.com/digoal@126/blog/static/16387704020161239252998/
数字计算CPU硬解
http://blog.163.com/digoal@126/blog/static/1638770402016237454462/
PG的优化器逻辑推理能力源码剖析
http://blog.163.com/digoal@126/blog/static/163877040201612374931160/
TPC-C 极限调优
https://github.com/digoal/pgsql_admin_script/blob/master/pgsql_perf_tuning
单机10亿 32位长度 正则，模糊检索 性能图表：
详细记录：
插入10亿数据，每条记录存储32位长随机字符串。
postgres=# create table t_regexp (info text);
CREATE TABLE
postgres=# insert into t_regexp select md5(random()::text) from generate_series(1,1000000000);
INSERT 0 1000000000
postgres=# create index idx_t_regexp_gin on t_regexp using gin (info gin_trgm_ops);
CREATE INDEX
postgres=# create index idx_t_regexp_1 on t_regexp (info);
CREATE INDEX
postgres=# create index idx_t_regexp_2 on t_regexp (reverse(info));
CREATE INDEX
使用auto_explain收集性能测试数据:
load 'auto_explain';
set auto_explain.log_analyze =true;
set auto_explain.log_buffers =true;
set auto_explain.log_nested_statements=true;
set auto_explain.log_timing=true;
set auto_explain.log_triggers=true;
set auto_explain.log_verbose=true;
set auto_explain.log_min_duration=0;
set client_min_messages ='log';
set work_mem='2GB';
测试数据概貌，总记录数10亿, 唯一数约8亿 如下：
digoal=> select count(*) from t_regexp ;
count
------------
1000000000
(1 row)
Time: 18547.746 ms
digoal=> select count(*) from (select info from t_regexp group by info) t;
count
-----------
799444838
(1 row)
带前缀模糊查询性能
有结果性能
digoal=# select ctid,* from t_regexp where info ~ '^9def5fe6343a5938b23af38444b7e' limit 10;
LOG: duration: 0.351 ms plan:
Query Text: select ctid,* from t_regexp where info ~ '^9def5fe6343a5938b23af38444b7e' limit 10;
Limit (cost=0.15..8.17 rows=1 width=39) (actual time=0.152..0.346 rows=2 loops=1)
Output: ctid, info
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=0.15..8.17 rows=1 width=39) (actual time=0.150..0.342 rows=2 loops=1)
Output: ctid, info
ctid | info
--------------+----------------------------------
(14720,1) | 9def5fe6343a5938b23af38444b7e350
(379127,105) | 9def5fe6343a5938b23af38444b7e350
(2 rows)
Time: 7.952 ms
无结果性能
digoal=# select ctid,* from t_regexp where info ~ '^9def5fe6343a5938b23af38444b7a' limit 10;
LOG: duration: 0.447 ms plan:
Query Text: select ctid,* from t_regexp where info ~ '^9def5fe6343a5938b23af38444b7a' limit 10;
Limit (cost=0.15..8.17 rows=1 width=39) (actual time=0.443..0.443 rows=0 loops=1)
Output: ctid, info
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=0.15..8.17 rows=1 width=39) (actual time=0.441..0.441 rows=0 loops=1)
Output: ctid, info
ctid | info
------+------
(0 rows)
Time: 7.968 ms
带后缀模糊查询性能
有结果性能
digoal=# select ctid,* from t_regexp where reverse(info) ~ '^1e346e5efc7703f11495';
LOG: duration: 5.287 ms plan:
Query Text: select ctid,* from t_regexp where reverse(info) ~ '^1e346e5efc7703f11495';
Remote Fast Query Execution (cost=0.00..0.00 rows=0 width=0) (actual time=4.943..5.281 rows=1 loops=1)
Output: t_regexp.ctid, t_regexp.info
Node/s: data1, data10, data11, data12, data13, data14, data15, data16, data2, data3, data4, data5, data6, data7, data8, data9
Remote query: SELECT ctid, info FROM t_regexp WHERE (reverse(info) ~ '^1e346e5efc7703f11495'::text)
ctid | info
------------+----------------------------------
(19928,46) | cc302768b6a459411f3077cfe5e643e1
(1 row)
Time: 6.079 ms
无结果性能
digoal=# select ctid,* from t_regexp where reverse(info) ~ '^1e346e5efc7703f11495123';
LOG: duration: 4.157 ms plan:
Query Text: select ctid,* from t_regexp where reverse(info) ~ '^1e346e5efc7703f11495123';
Remote Fast Query Execution (cost=0.00..0.00 rows=0 width=0) (actual time=4.154..4.154 rows=0 loops=1)
Output: t_regexp.ctid, t_regexp.info
Node/s: data1, data10, data11, data12, data13, data14, data15, data16, data2, data3, data4, data5, data6, data7, data8, data9
Remote query: SELECT ctid, info FROM t_regexp WHERE (reverse(info) ~ '^1e346e5efc7703f11495123'::text)
ctid | info
------+------
(0 rows)
Time: 4.930 ms
前后模糊查询性能
有结果性能
digoal=# select ctid,* from t_regexp where info ~ '6ccd8ca827b0526cd57a71c949' order by info <-> '6ccd8ca827b0526cd57a71c949' limit 10;
LOG: duration: 3066.193 ms plan:
Query Text: select ctid,* from t_regexp where info ~ '6ccd8ca827b0526cd57a71c949' order by info <-> '6ccd8ca827b0526cd57a71c949' limit 10;
Limit (cost=72.03..72.03 rows=1 width=39) (actual time=3066.175..3066.176 rows=1 loops=1)
Output: ctid, info, ((info <-> '6ccd8ca827b0526cd57a71c949'::text))
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=72.03..72.03 rows=1 width=39) (actual time=3066.173..3066.174 rows=1 loops=1)
Output: ctid, info, (info <-> '6ccd8ca827b0526cd57a71c949'::text)
ctid | info
--------------+----------------------------------
(459019,106) | 8536ccd8ca827b0526cd57a71c949ab2
(1 row)
Time: 3074.907 ms
无结果性能
digoal=# select ctid,* from t_regexp where info ~ '6ccd8ca827b0526cd57a71c123' order by info <-> '6ccd8ca827b0526cd57a71c123' limit 10;
LOG: duration: 3099.348 ms plan:
Query Text: select ctid,* from t_regexp where info ~ '6ccd8ca827b0526cd57a71c123' order by info <-> '6ccd8ca827b0526cd57a71c123' limit 10;
Limit (cost=72.03..72.03 rows=1 width=39) (actual time=3099.341..3099.341 rows=0 loops=1)
Output: ctid, info, ((info <-> '6ccd8ca827b0526cd57a71c123'::text))
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=72.03..72.03 rows=1 width=39) (actual time=3099.339..3099.339 rows=0 loops=1)
Output: ctid, info, (info <-> '6ccd8ca827b0526cd57a71c123'::text)
ctid | info
------+------
(0 rows)
Time: 3108.698 ms
使用了GIN索引
digoal=# explain (verbose) select ctid,* from t_regexp where info ~ '6ccd8ca827b0526cd57a71c123' order by info <-> '6ccd8ca827b0526cd57a71c123' limit 10;
LOG: duration: 0.000 ms plan:
Query Text: explain (verbose) select ctid,* from t_regexp where info ~ '6ccd8ca827b0526cd57a71c123' order by info <-> '6ccd8ca827b0526cd57a71c123' limit 10;
Limit (cost=72.03..72.03 rows=1 width=39)
Output: ctid, info, ((info <-> '6ccd8ca827b0526cd57a71c123'::text))
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=72.03..72.03 rows=1 width=39)
Output: ctid, info, (info <-> '6ccd8ca827b0526cd57a71c123'::text)
-> Limit (cost=72.03..72.03 rows=1 width=39)
Output: ctid, info, ((info <-> '6ccd8ca827b0526cd57a71c123'::text))
-> Sort (cost=72.03..72.03 rows=1 width=39)
Output: ctid, info, ((info <-> '6ccd8ca827b0526cd57a71c123'::text))
Sort Key: ((t_regexp.info <-> '6ccd8ca827b0526cd57a71c123'::text))
-> Bitmap Heap Scan on public.t_regexp (cost=68.00..72.02 rows=1 width=39)
Output: ctid, info, (info <-> '6ccd8ca827b0526cd57a71c123'::text)
Recheck Cond: (t_regexp.info ~ '6ccd8ca827b0526cd57a71c123'::text)
-> Bitmap Index Scan on idx_t_regexp_gin (cost=0.00..68.00 rows=1 width=0)
Index Cond: (t_regexp.info ~ '6ccd8ca827b0526cd57a71c123'::text)
正则匹配查询性能
有结果性能(例如0和8,B,6和b混淆)
digoal=# select ctid,* from t_regexp where info ~ 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]efb' order by info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]efb' limit 10;
LOG: duration: 3181.592 ms plan:
Query Text: select ctid,* from t_regexp where info ~ 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]efb' order by info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]efb' limit 10;
Limit (cost=72.03..72.03 rows=1 width=39) (actual time=3181.568..3181.569 rows=2 loops=1)
Output: ctid, info, ((info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]efb'::text))
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=72.03..72.03 rows=1 width=39) (actual time=3181.566..3181.566 rows=2 loops=1)
Output: ctid, info, (info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]efb'::text)
ctid | info
--------------+----------------------------------
(260416,110) | b44c9616bfa86a722daa9596f86ebefb
(504007,4) | b44c9616bfa86a722daa9596f86ebefb
(2 rows)
Time: 3189.666 ms
又如再加难度，中间忘记了几个字符，只知道是数字，并且可能是2到5个数字
digoal=# select ctid,* from t_regexp where info ~ 'b44c9616bfa[8|0|B]6a722daa[\d]{2,5}6f86e[b|6]efb' order by info <-> 'b44c9616bfa[8|0|B]6a722daa[0-9]{2,5}6f86e[b|6]efb' limit 10;
LOG: duration: 3249.156 ms plan:
Query Text: select ctid,* from t_regexp where info ~ 'b44c9616bfa[8|0|B]6a722daa[\d]{2,5}6f86e[b|6]efb' order by info <-> 'b44c9616bfa[8|0|B]6a722daa[0-9]{2,5}6f86e[b|6]efb' limit 10;
Limit (cost=72.03..72.03 rows=1 width=39) (actual time=3249.136..3249.137 rows=2 loops=1)
Output: ctid, info, ((info <-> 'b44c9616bfa[8|0|B]6a722daa[0-9]{2,5}6f86e[b|6]efb'::text))
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=72.03..72.03 rows=1 width=39) (actual time=3249.134..3249.134 rows=2 loops=1)
Output: ctid, info, (info <-> 'b44c9616bfa[8|0|B]6a722daa[0-9]{2,5}6f86e[b|6]efb'::text)
ctid | info
--------------+----------------------------------
(260416,110) | b44c9616bfa86a722daa9596f86ebefb
(504007,4) | b44c9616bfa86a722daa9596f86ebefb
(2 rows)
Time: 3257.435 ms
无结果性能
digoal=# select ctid,* from t_regexp where info ~ 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]e12' order by info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]e12' limit 10;
LOG: duration: 3086.572 ms plan:
Query Text: select ctid,* from t_regexp where info ~ 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]e12' order by info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]e12' limit 10;
Limit (cost=72.03..72.03 rows=1 width=39) (actual time=3086.567..3086.567 rows=0 loops=1)
Output: ctid, info, ((info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]e12'::text))
-> Remote Subquery Scan on all (data1,data10,data11,data12,data13,data14,data15,data16,data2,data3,data4,data5,data6,data7,data8,data9) (cost=72.03..72.03 rows=1 width=39) (actual time=3086.565..3086.565 rows=0 loops=1)
Output: ctid, info, (info <-> 'b44c9616bfa[8|0|B]6a722daa9596f86e[b|6]e12'::text)
ctid | info
------+------
(0 rows)
Time: 3094.683 ms
您的愿望将传达给PG kernel hacker、数据库厂商等, 帮助提高数据库产品质量和功能, 说不定下一个PG版本就有您提出的功能点. 针对非常好的提议，奖励限量版PG文化衫、纪念品、贴纸、PG热门书籍等，奖品丰富，快来许愿。开不开森.
