前言或者说切片的想法是如何产生的
故事从这里开始:
抒情题外话:
正是“那一刻”,因为
那么,怎样才能让客户满意,同时提高自己的技能呢?
尽可能地简化一切,那么只有两种方法可以从根本上提高数据库的性能:
1)粗放路径——我们增加资源,改变配置;
2)强化路径——查询优化
我再说一遍,因为当时不再清楚在加速请求中还需要改变什么,所以选择了路径 - 表设计变更。
初始条件
首先,有这个 ERD(以有条件简化的方式显示):
主要特点:
- 多对多关系
- 该表已经有一个潜在的分区键
原始请求:
SELECT
p."PARAMETER_ID" as parameter_id,
pc."PC_NAME" AS pc_name,
pc."CUSTOMER_PARTNUMBER" AS customer_partnumber,
w."LASERMARK" AS lasermark,
w."LOTID" AS lotid,
w."REPORTED_VALUE" AS reported_value,
w."LOWER_SPEC_LIMIT" AS lower_spec_limit,
w."UPPER_SPEC_LIMIT" AS upper_spec_limit,
p."TYPE_CALCUL" AS type_calcul,
s."SHIPMENT_NAME" AS shipment_name,
s."SHIPMENT_DATE" AS shipment_date,
extract(year from s."SHIPMENT_DATE") AS year,
extract(month from s."SHIPMENT_DATE") as month,
s."REPORT_NAME" AS report_name,
p."SPARAM_NAME" AS SPARAM_name,
p."CUSTOMERPARAM_NAME" AS customerparam_name
FROM data w INNER JOIN shipment s ON s."SHIPMENT_ID" = w."SHIPMENT_ID"
INNER JOIN parameters p ON p."PARAMETER_ID" = w."PARAMETER_ID"
INNER JOIN shipment_pc sp ON s."SHIPMENT_ID" = sp."SHIPMENT_ID"
INNER JOIN pc pc ON pc."PC_ID" = sp."PC_ID"
INNER JOIN ( SELECT w2."LASERMARK" , MAX(s2."SHIPMENT_DATE") AS "SHIPMENT_DATE"
FROM shipment s2 INNER JOIN data w2 ON s2."SHIPMENT_ID" = w2."SHIPMENT_ID"
GROUP BY w2."LASERMARK"
) md ON md."SHIPMENT_DATE" = s."SHIPMENT_DATE" AND md."LASERMARK" = w."LASERMARK"
WHERE
s."SHIPMENT_DATE" >= '2018-07-01' AND s."SHIPMENT_DATE" <= '2018-09-30' ;
在测试数据库上执行结果:
价格 :502 997.55
执行时间处理时间:505秒
我们看到了什么? 基于时间片的常规请求。
让我们做一个最简单的逻辑假设:如果有一个时间片的样本,它会对我们有帮助吗? 没错——分区。
划分什么?
乍一看,选择是显而易见的 - 使用“SHIPMENT_DATE”键对“shipment”表进行声明性分区(跳得太远了——最终结果在生产中出了点问题).
如何分区?
这个问题也不是太难。 幸运的是,在 PostgreSQL 10 中,现在有了人工分区机制。
所以:
- 保存源表的转储 - pg_dump 源表
- 删除原表—— 删除表source_table
- 创建具有范围分区的父表 - 创建表source_table
- 创建部分 - 创建表source_table,创建索引
- 导入步骤 1 中创建的转储 - pg_恢复
分区脚本
为了简单和方便,步骤 2,3,4、XNUMX、XNUMX 已合并为一个脚本。
所以:
保存源表的转储
pg_dump postgres --file=/dump/shipment.dmp --format=c --table=shipment --verbose > /dump/shipment.log 2>&1
删除源表+创建范围分区的父表+创建分区
--create_partition_shipment.sql
do language plpgsql $$
declare
rec_shipment_date RECORD ;
partition_name varchar;
index_name varchar;
current_year varchar ;
current_month varchar ;
begin_year varchar ;
begin_month varchar ;
next_year varchar ;
next_month varchar ;
first_flag boolean ;
i integer ;
begin
RAISE NOTICE 'CREATE TEMPORARY TABLE FOR SHIPMENT_DATE';
CREATE TEMP TABLE tmp_shipment_date as select distinct "SHIPMENT_DATE" from shipment order by "SHIPMENT_DATE" ;
RAISE NOTICE 'DROP TABLE shipment';
drop table shipment cascade ;
CREATE TABLE public.shipment
(
"SHIPMENT_ID" integer NOT NULL DEFAULT nextval('shipment_shipment_id_seq'::regclass),
"SHIPMENT_NAME" character varying(30) COLLATE pg_catalog."default",
"SHIPMENT_DATE" timestamp without time zone,
"REPORT_NAME" character varying(40) COLLATE pg_catalog."default"
)
PARTITION BY RANGE ("SHIPMENT_DATE")
WITH (
OIDS = FALSE
)
TABLESPACE pg_default;
RAISE NOTICE 'CREATE PARTITIONS FOR TABLE shipment';
current_year:='0';
current_month:='0';
begin_year := '0' ;
begin_month := '0' ;
next_year := '0' ;
next_month := '0' ;
FOR rec_shipment_date IN SELECT * FROM tmp_shipment_date LOOP
RAISE NOTICE 'SHIPMENT_DATE=%',rec_shipment_date."SHIPMENT_DATE";
current_year := date_part('year' ,rec_shipment_date."SHIPMENT_DATE");
current_month := date_part('month' ,rec_shipment_date."SHIPMENT_DATE") ;
IF to_number(current_month,'99') < 10 THEN
current_month := '0'||current_month ;
END IF ;
--Init borders
IF begin_year = '0' THEN
first_flag := true ; --first time flag
begin_year := current_year ;
begin_month := current_month ;
IF current_month = '12' THEN
next_year := date_part('year' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 year') ;
ELSE
next_year := current_year ;
END IF;
next_month := date_part('month' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 month') ;
END IF;
-- Check current date into borders NOT for First time
IF to_date( current_year||'.'||current_month, 'YYYY.MM') >= to_date( begin_year||'.'||begin_month, 'YYYY.MM') AND
to_date( current_year||'.'||current_month, 'YYYY.MM') < to_date( next_year||'.'||next_month, 'YYYY.MM') AND
NOT first_flag
THEN
CONTINUE ;
ELSE
--NEW borders only for second and after time
begin_year := current_year ;
begin_month := current_month ;
IF current_month = '12' THEN
next_year := date_part('year' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 year') ;
ELSE
next_year := current_year ;
END IF;
next_month := date_part('month' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 month') ;
END IF;
partition_name := 'shipment_shipment_date_'||begin_year||'-'||begin_month||'-01-'|| next_year||'-'||next_month||'-01' ;
EXECUTE format('CREATE TABLE ' || quote_ident(partition_name) || ' PARTITION OF shipment FOR VALUES FROM ( %L ) TO ( %L ) ' , current_year||'-'||current_month||'-01' , next_year||'-'||next_month||'-01' ) ;
index_name := partition_name||'_shipment_id_idx';
RAISE NOTICE 'INDEX NAME =%',index_name;
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_ID") TABLESPACE pg_default ' ) ;
--Drop first time flag
first_flag := false ;
END LOOP;
end
$$;
导入转储
pg_restore -d postgres --data-only --format=c --table=shipment --verbose shipment.dmp > /tmp/data_dump/shipment_restore.log 2>&1
检查分区结果
结果是什么? 执行计划的全文又大又乏味,因此很可能仅限于最终的数字。
这是
费用: 502 997.55
执行时间处理时间: 505秒。
它成了
费用: 77 872.36
执行时间处理时间: 79秒。
相当不错的结果。 降低了成本和执行时间。 因此,分区的使用给出了预期的效果,并且通常不会令人意外。
让顾客高兴
测试结果提交给客户审核。 经过审查后,他们得到了一个有点出乎意料的结论:“太好了,对‘数据’表进行分区。”
是的,但我们检查了一个完全不同的“shipment”表;“data”表没有“SHIPMENT_DATE”字段。
没问题,添加、更改。 最主要的是客户对结果满意,实施细节并不是特别重要。
对主表“数据”进行分区
总的来说,没有出现什么特别的困难。 当然,分区算法已经发生了一些变化。
将“SHIPMENT_DATA”列添加到“data”表中
psql -h хост -U база -d юзер
=> ALTER TABLE data ADD COLUMN "SHIPMENT_DATE" timestamp without time zone ;
将“data”表中“SHIPMENT_DATA”列的值填写为“shipment”表中同名列的值
-----------------------------
--update_data.sql
--updating for altered table "data" to values of "shipment_data" from the table "shipment"
--version 1.0
do language plpgsql $$
declare
rec_shipment_data RECORD ;
shipment_date timestamp without time zone ;
row_count integer ;
total_rows integer ;
begin
select count(*) into total_rows from shipment ;
RAISE NOTICE 'Total %',total_rows;
row_count:= 0 ;
FOR rec_shipment_data IN SELECT * FROM shipment LOOP
update data set "SHIPMENT_DATE" = rec_shipment_data."SHIPMENT_DATE" where "SHIPMENT_ID" = rec_shipment_data."SHIPMENT_ID";
row_count:= row_count +1 ;
RAISE NOTICE 'row count = % , from %',row_count,total_rows;
END LOOP;
end
$$;
保存“数据”表的转储
pg_dump postgres --file=/dump/data.dmp --format=c --table=data --verbose > /dump/data.log 2>&1</source
重新创建分区表“data”
--create_partition_data.sql
--create partitions for the table "wafer data" by range column "shipment_data" with one month duration
--version 1.0
do language plpgsql $$
declare
rec_shipment_date RECORD ;
partition_name varchar;
index_name varchar;
current_year varchar ;
current_month varchar ;
begin_year varchar ;
begin_month varchar ;
next_year varchar ;
next_month varchar ;
first_flag boolean ;
i integer ;
begin
RAISE NOTICE 'CREATE TEMPORARY TABLE FOR SHIPMENT_DATE';
CREATE TEMP TABLE tmp_shipment_date as select distinct "SHIPMENT_DATE" from shipment order by "SHIPMENT_DATE" ;
RAISE NOTICE 'DROP TABLE data';
drop table data cascade ;
RAISE NOTICE 'CREATE PARTITIONED TABLE data';
CREATE TABLE public.data
(
"RUN_ID" integer,
"LASERMARK" character varying(20) COLLATE pg_catalog."default" NOT NULL,
"LOTID" character varying(80) COLLATE pg_catalog."default",
"SHIPMENT_ID" integer NOT NULL,
"PARAMETER_ID" integer NOT NULL,
"INTERNAL_VALUE" character varying(75) COLLATE pg_catalog."default",
"REPORTED_VALUE" character varying(75) COLLATE pg_catalog."default",
"LOWER_SPEC_LIMIT" numeric,
"UPPER_SPEC_LIMIT" numeric ,
"SHIPMENT_DATE" timestamp without time zone
)
PARTITION BY RANGE ("SHIPMENT_DATE")
WITH (
OIDS = FALSE
)
TABLESPACE pg_default ;
RAISE NOTICE 'CREATE PARTITIONS FOR TABLE data';
current_year:='0';
current_month:='0';
begin_year := '0' ;
begin_month := '0' ;
next_year := '0' ;
next_month := '0' ;
i := 1;
FOR rec_shipment_date IN SELECT * FROM tmp_shipment_date LOOP
RAISE NOTICE 'SHIPMENT_DATE=%',rec_shipment_date."SHIPMENT_DATE";
current_year := date_part('year' ,rec_shipment_date."SHIPMENT_DATE");
current_month := date_part('month' ,rec_shipment_date."SHIPMENT_DATE") ;
--Init borders
IF begin_year = '0' THEN
RAISE NOTICE '***Init borders';
first_flag := true ; --first time flag
begin_year := current_year ;
begin_month := current_month ;
IF current_month = '12' THEN
next_year := date_part('year' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 year') ;
ELSE
next_year := current_year ;
END IF;
next_month := date_part('month' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 month') ;
END IF;
-- RAISE NOTICE 'current_year=% , current_month=% ',current_year,current_month;
-- RAISE NOTICE 'begin_year=% , begin_month=% ',begin_year,begin_month;
-- RAISE NOTICE 'next_year=% , next_month=% ',next_year,next_month;
-- Check current date into borders NOT for First time
RAISE NOTICE 'Current data = %',to_char( to_date( current_year||'.'||current_month, 'YYYY.MM'), 'YYYY.MM');
RAISE NOTICE 'Begin data = %',to_char( to_date( begin_year||'.'||begin_month, 'YYYY.MM'), 'YYYY.MM');
RAISE NOTICE 'Next data = %',to_char( to_date( next_year||'.'||next_month, 'YYYY.MM'), 'YYYY.MM');
IF to_date( current_year||'.'||current_month, 'YYYY.MM') >= to_date( begin_year||'.'||begin_month, 'YYYY.MM') AND
to_date( current_year||'.'||current_month, 'YYYY.MM') < to_date( next_year||'.'||next_month, 'YYYY.MM') AND
NOT first_flag
THEN
RAISE NOTICE '***CONTINUE';
CONTINUE ;
ELSE
--NEW borders only for second and after time
RAISE NOTICE '***NEW BORDERS';
begin_year := current_year ;
begin_month := current_month ;
IF current_month = '12' THEN
next_year := date_part('year' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 year') ;
ELSE
next_year := current_year ;
END IF;
next_month := date_part('month' ,rec_shipment_date."SHIPMENT_DATE" + interval '1 month') ;
END IF;
IF to_number(current_month,'99') < 10 THEN
current_month := '0'||current_month ;
END IF ;
IF to_number(begin_month,'99') < 10 THEN
begin_month := '0'||begin_month ;
END IF ;
IF to_number(next_month,'99') < 10 THEN
next_month := '0'||next_month ;
END IF ;
RAISE NOTICE 'current_year=% , current_month=% ',current_year,current_month;
RAISE NOTICE 'begin_year=% , begin_month=% ',begin_year,begin_month;
RAISE NOTICE 'next_year=% , next_month=% ',next_year,next_month;
partition_name := 'data_'||begin_year||begin_month||'01_'||next_year||next_month||'01' ;
RAISE NOTICE 'PARTITION NUMBER % , TABLE NAME =%',i , partition_name;
EXECUTE format('CREATE TABLE ' || quote_ident(partition_name) || ' PARTITION OF data FOR VALUES FROM ( %L ) TO ( %L ) ' , begin_year||'-'||begin_month||'-01' , next_year||'-'||next_month||'-01' ) ;
index_name := partition_name||'_shipment_id_parameter_id_idx';
RAISE NOTICE 'INDEX NAME =%',index_name;
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_ID", "PARAMETER_ID") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_lasermark_idx';
RAISE NOTICE 'INDEX NAME =%',index_name;
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("LASERMARK" COLLATE pg_catalog."default") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_shipment_id_idx';
RAISE NOTICE 'INDEX NAME =%',index_name;
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_ID") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_parameter_id_idx';
RAISE NOTICE 'INDEX NAME =%',index_name;
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("PARAMETER_ID") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_shipment_date_idx';
RAISE NOTICE 'INDEX NAME =%',index_name;
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_DATE") TABLESPACE pg_default ' ) ;
--Drop first time flag
first_flag := false ;
END LOOP;
end
$$;
加载在步骤 3 中创建的转储。
pg_restore -h хост -юзер -d база --data-only --format=c --table=data --verbose data.dmp > data_restore.log 2>&1
为旧数据创建一个单独的部分
---------------------------------------------------
--create_partition_for_old_dates.sql
--create partitions for keeping old dates
--version 1.0
do language plpgsql $$
declare
rec_shipment_date RECORD ;
partition_name varchar;
index_name varchar;
begin
SELECT min("SHIPMENT_DATE") AS min_date INTO rec_shipment_date from data ;
RAISE NOTICE 'Old date is %',rec_shipment_date.min_date ;
partition_name := 'data_old_dates' ;
RAISE NOTICE 'PARTITION NAME IS %',partition_name;
EXECUTE format('CREATE TABLE ' || quote_ident(partition_name) || ' PARTITION OF data FOR VALUES FROM ( %L ) TO ( %L ) ' , '1900-01-01' ,
to_char( rec_shipment_date.min_date,'YYYY')||'-'||to_char(rec_shipment_date.min_date,'MM')||'-01' ) ;
index_name := partition_name||'_shipment_id_parameter_id_idx';
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_ID", "PARAMETER_ID") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_lasermark_idx';
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("LASERMARK" COLLATE pg_catalog."default") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_shipment_id_idx';
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_ID") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_parameter_id_idx';
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("PARAMETER_ID") TABLESPACE pg_default ' ) ;
index_name := partition_name||'_shipment_date_idx';
EXECUTE format('CREATE INDEX ' || quote_ident(index_name) || ' ON '|| quote_ident(partition_name) ||' USING btree ("SHIPMENT_DATE") TABLESPACE pg_default ' ) ;
end
$$;
最终结果:
这是
费用: 502 997.55
执行时间处理时间:505秒
它成了
费用: 68 533.70
执行时间处理时间: 69秒
值得,相当值得。 考虑到一路走来,我们或多或少地掌握了 PostgreSQL 10 中的分区机制——这是一个非常好的结果。
抒情撤退
是否有可能做得更好 - 是的,你可以!为此,您需要使用物化视图。
创建物化视图 LASERMARK_VIEW
CREATE MATERIALIZED VIEW LASERMARK_VIEW
AS
SELECT w."LASERMARK" , MAX(s."SHIPMENT_DATE") AS "SHIPMENT_DATE"
FROM shipment s INNER JOIN data w ON s."SHIPMENT_ID" = w."SHIPMENT_ID"
GROUP BY w."LASERMARK" ;
CREATE INDEX lasermark_vw_shipment_date_ind on lasermark_view USING btree ("SHIPMENT_DATE") TABLESPACE pg_default;
analyze lasermark_view ;
我们再次重写请求:
使用物化视图查询
SELECT
p."PARAMETER_ID" as parameter_id,
pc."PC_NAME" AS pc_name,
pc."CUSTOMER_PARTNUMBER" AS customer_partnumber,
w."LASERMARK" AS lasermark,
w."LOTID" AS lotid,
w."REPORTED_VALUE" AS reported_value,
w."LOWER_SPEC_LIMIT" AS lower_spec_limit,
w."UPPER_SPEC_LIMIT" AS upper_spec_limit,
p."TYPE_CALCUL" AS type_calcul,
s."SHIPMENT_NAME" AS shipment_name,
s."SHIPMENT_DATE" AS shipment_date,
extract(year from s."SHIPMENT_DATE") AS year,
extract(month from s."SHIPMENT_DATE") as month,
s."REPORT_NAME" AS report_name,
p."STC_NAME" AS STC_name,
p."CUSTOMERPARAM_NAME" AS customerparam_name
FROM data w INNER JOIN shipment s ON s."SHIPMENT_ID" = w."SHIPMENT_ID"
INNER JOIN parameters p ON p."PARAMETER_ID" = w."PARAMETER_ID"
INNER JOIN shipment_pc sp ON s."SHIPMENT_ID" = sp."SHIPMENT_ID"
INNER JOIN pc pc ON pc."PC_ID" = sp."PC_ID"
INNER JOIN LASERMARK_VIEW md ON md."SHIPMENT_DATE" = s."SHIPMENT_DATE" AND md."LASERMARK" = w."LASERMARK"
WHERE
s."SHIPMENT_DATE" >= '2018-07-01' AND s."SHIPMENT_DATE" <= '2018-09-30';
我们得到另一个结果:
这是
费用: 502 997.55
执行时间处理时间:505秒
它成了
费用: 42 481.16
执行时间处理时间: 43秒。
当然,尽管这样一个有希望的结果具有欺骗性,但想法需要更新。 所以接收数据的总时间不会有太大帮助。 但作为一个实验,它是相当有趣的。
事实上,事实证明,再次感谢
后记
所以,客户很满意。 和 必要 利用这种情况。
新任务:您能想出什么来深化和扩展?
然后我想起来了——伙计们,我们没有对 PostgreSQL 数据库进行监控。
实际上,AWS 上仍然有一些以 Cloud Watch 形式进行的监控。 但这种监控对于 DBA 来说有什么好处呢? 一般来说,几乎没有。
如果您有机会为自己做一些有用且有趣的事情,您就不能不利用这个机会......
BECAUSE
这就是我们如何来到最有趣的部分:
3 年 2018 月 XNUMX 日。
决定开始研究监控 PostgreSQL 查询性能的可用功能。
但这是一个完全不同的故事。
待续…
来源: habr.com