improve

Author: digoal

201803/20180326_01.md

@@ -1846,6 +1846,119 @@ postgres=# select * from tt;
 (7 rows)
 ```  
 
+## 17 同步模式 VS 异步模式 性能对比  
+  
+1、生成1亿TPC-B测试数据  
+  
+```  
+pgbench -i -s 1000  
+```  
+  
+2、多副本同步模式  
+  
+```  
+postgres=# show synchronous_commit ;  
+ synchronous_commit   
+--------------------  
+ remote_write  
+(1 row)  
+  
+postgres=# show synchronous_standby_names ;  
+ synchronous_standby_names   
+---------------------------  
+ ANY 1 (*)  
+(1 row)  
+```  
+  
+3、压测  
+  
+```  
+pgbench -M prepared -n -r -P 1 -c 56 -j 56 -T 120  
+  
+transaction type: <builtin: TPC-B (sort of)>  
+scaling factor: 1000  
+query mode: prepared  
+number of clients: 56  
+number of threads: 56  
+duration: 120 s  
+number of transactions actually processed: 5381146  
+latency average = 1.248 ms  
+latency stddev = 4.118 ms  
+tps = 44840.272218 (including connections establishing)  
+tps = 44853.145859 (excluding connections establishing)  
+script statistics:  
+ - statement latencies in milliseconds:  
+         0.002  \set aid random(1, 100000 * :scale)  
+         0.001  \set bid random(1, 1 * :scale)  
+         0.001  \set tid random(1, 10 * :scale)  
+         0.001  \set delta random(-5000, 5000)  
+         0.063  BEGIN;  
+         0.171  UPDATE pgbench_accounts SET abalance = abalance + :delta WHERE aid = :aid;  
+         0.096  SELECT abalance FROM pgbench_accounts WHERE aid = :aid;  
+         0.109  UPDATE pgbench_tellers SET tbalance = tbalance + :delta WHERE tid = :tid;  
+         0.118  UPDATE pgbench_branches SET bbalance = bbalance + :delta WHERE bid = :bid;  
+         0.090  INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES (:tid, :bid, :aid, :delta, CURRENT_TIMESTAMP);  
+         0.597  END;  
+```  
+  
+4、本地持久化，单副本模式  
+  
+```  
+postgres@-> psql  
+psql (10.3)  
+Type "help" for help.  
+  
+postgres=# alter role postgres set synchronous_commit = local;  
+ALTER ROLE  
+postgres=# \q  
+postgres@-> psql  
+psql (10.3)  
+Type "help" for help.  
+  
+postgres=# show synchronous_commit ;  
+ synchronous_commit   
+--------------------  
+ local  
+(1 row)  
+```  
+  
+5、压测  
+  
+```  
+pgbench -M prepared -n -r -P 1 -c 56 -j 56 -T 120  
+  
+transaction type: <builtin: TPC-B (sort of)>  
+scaling factor: 1000  
+query mode: prepared  
+number of clients: 56  
+number of threads: 56  
+duration: 120 s  
+number of transactions actually processed: 6684833  
+latency average = 1.005 ms  
+latency stddev = 1.494 ms  
+tps = 55695.800213 (including connections establishing)  
+tps = 55700.524316 (excluding connections establishing)  
+script statistics:  
+ - statement latencies in milliseconds:  
+         0.002  \set aid random(1, 100000 * :scale)  
+         0.001  \set bid random(1, 1 * :scale)  
+         0.001  \set tid random(1, 10 * :scale)  
+         0.001  \set delta random(-5000, 5000)  
+         0.061  BEGIN;  
+         0.133  UPDATE pgbench_accounts SET abalance = abalance + :delta WHERE aid = :aid;  
+         0.096  SELECT abalance FROM pgbench_accounts WHERE aid = :aid;  
+         0.108  UPDATE pgbench_tellers SET tbalance = tbalance + :delta WHERE tid = :tid;  
+         0.114  UPDATE pgbench_branches SET bbalance = bbalance + :delta WHERE bid = :bid;  
+         0.091  INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES (:tid, :bid, :aid, :delta, CURRENT_TIMESTAMP);  
+         0.400  END;  
+```  
+  
+OLTP写场景本地持久化 VS 多副本性能对比：  
+  
+1、多副本模式，RT 提高了0.24毫秒，约20%     
+  
+2、多副本模式，TPS 下降了10855，约20%     
+    
 ## 小结  
 
 PostgreSQL的多副本复制非常的简单并且健壮。  

201804/20180417_01.md

@@ -143,6 +143,7 @@ postgres=# explain select * from t_test where pos like 'yuhdce4%';
 ```  
 
 ### 2、geohash 范围扫描，匹配在一个连续Z空间中的一段小方格  
+![pic](20180417_01_pic_009.png)  
 
 将二进制编码的结果填写到空间中，当将空间划分为四块时候，编码的顺序分别是左下角00，左上角01，右下脚10，右上角11，也就是类似于Z的曲线，当我们递归的将各个块分解成更小的子块时，编码的顺序是自相似的（分形），每一个子快也形成Z曲线，这种类型的曲线被称为Peano空间填充曲线。