我有 7 个表可以加入单选查询。但是，当我加入 5 个表中的任何一个时，它工作正常，但加入 7 个表会使查询无响应。而只有大约 2k 条记录可供选择。这是我的查询：
select c.i_cdr, v.i_cdrs_connection, c.i_call,
cs.name AS customer_name, a.username AS client_name_id,
con.name AS connection_name, vn.name AS vendor_name_id,
ca.setup_time,
c.remote_ip AS c_remote_ip_id, con.destination AS v_remote_ip_id
FROM cdrs c
JOIN Calls ca using (i_call)
JOIN cdrs_connections v using (i_call)
JOIN accounts a using(i_account)
JOIN customers cs using (i_customer)
JOIN connections con using(i_connection)
JOIN vendors vn using (i_vendor)
where i_cdr>397233018
如果对单个查询中的最大表数或最大列数有任何限制？
我试过减少列但没有用。
postgresql 配置。
postgres 8.4
shared_buffers = 128MB
work_mem = 32MB
maintenance_work_mem = 64MB
来电表：
Create Table calls
(
i_call serial Not null,
setup_time timestamp Not Null,
cli character varying(64),
cld character varying(64)
)
cdrs 表：
Create Table cdrs
(
i_cdr serial Not null,
i_call bigint Not Null,
remote_ip character varying(64),
i_account bigint Not Null
//few more not used fields
)
账户表：
Create Table accounts
(
i_account serial Not null,
i_customer bigint Not Null,
username character varying(128)
)
客户表：
Create Table customers
(
i_customer serial Not null,
name character varying(128)
)
cdrs_connections：
Create Table cdrs_connections
(
i_cdrs_connection serial Not null,
i_call bigint Not null,
i_connection bigint Not null,
connect_time timestamp,
cld_out character varying(64),
cli_out character varying(128)
)
连接：
Create Table connections
(
i_connection serial Not null,
i_vendor bigint Not null,
name varying character(64),
destination character varying(64)
)
供应商：
Create Table vendors
(
i_vendor serial Not null,
name character varying(64)
);
解释跟踪：
遍历的主要表是分区的，即使我排除具有 500 行的帐户和具有 26 行的客户也可以正常工作。
查询计划
Nested Loop (cost=3388.21..3202797988160500.00 rows=6369283937505514496 width=122)
Join Filter: (c.i_call = ca.i_call)
-> Nested Loop (cost=3388.21..29281315906299.16 rows=12704473261254 width=122)
-> Hash Join (cost=3388.21..310816005731.24 rows=12704473261254 width=121)
Hash Cond: (c.i_account = a.i_account)
-> Nested Loop (cost=0.00..24965353964.82 rows=12704473261254 width=112)
Join Filter: (v.i_call = c.i_call)
-> Nested Loop (cost=0.00..1708130302.64 rows=61256189 width=69)
-> Nested Loop (cost=0.00..465977965.21 rows=61256189 width=60)
-> Append (cost=0.00..6600178.80 rows=61256189 width=24)
-> Index Scan using cdrs_connections_i_call on cdrs_connections v (cost=0.00..22.03 rows=310 width=24)
-> Index Scan using cdrs_connections1_i_call on cdrs_connections1 v (cost=0.00..219415.43 rows=568528 width=24)
-> Index Scan using cdrs_connections2_i_call on cdrs_connections2 v (cost=0.00..34433.40 rows=536331 width=24)
-> Index Scan using cdrs_connections3_i_call on cdrs_connections3 v (cost=0.00..359871.77 rows=885115 width=24)
-> Index Scan using cdrs_connections4_i_call on cdrs_connections4 v (cost=0.00..84725.16 rows=1316695 width=24)
-> Index Scan using cdrs_connections5_i_call on cdrs_connections5 v (cost=0.00..66291.88 rows=1046102 width=24)
-> Index Scan using cdrs_connections6_i_call on cdrs_connections6 v (cost=0.00..74410.59 rows=1043184 width=24)
-> Index Scan using cdrs_connections7_i_call on cdrs_connections7 v (cost=0.00..79614.35 rows=1244914 width=24)
-> Index Scan using cdrs_connections8_i_call on cdrs_connections8 v (cost=0.00..78292.13 rows=1228840 width=24)
-> Index Scan using cdrs_connections9_i_call on cdrs_connections9 v (cost=0.00..23.84 rows=320 width=24)
-> Index Scan using cdrs_connections10_i_call on cdrs_connections10 v (cost=0.00..869491.71 rows=1326456 width=24)
-> Index Scan using cdrs_connections11_i_call on cdrs_connections11 v (cost=0.00..84478.96 rows=1329600 width=24)
-> Index Scan using cdrs_connections12_i_call on cdrs_connections12 v (cost=0.00..34373.13 rows=529498 width=24)
-> Index Scan using cdrs_connections13_i_call on cdrs_connections13 v (cost=0.00..47.28 rows=330 width=24)
-> Index Scan using cdrs_connections14_i_call on cdrs_connections14 v (cost=0.00..33623.46 rows=506174 width=24)
-> Index Scan using cdrs_connections15_i_call on cdrs_connections15 v (cost=0.00..31732.57 rows=485078 width=24)
-> Index Scan using cdrs_connections16_i_call on cdrs_connections16 v (cost=0.00..29434.18 rows=460046 width=24)
-> Index Scan using cdrs_connections17_i_call on cdrs_connections17 v (cost=0.00..32157.93 rows=500074 width=24)
-> Index Scan using cdrs_connections18_i_call on cdrs_connections18 v (cost=0.00..35811.81 rows=561528 width=24)
-> Index Scan using cdrs_connections19_i_call on cdrs_connections19 v (cost=0.00..157742.69 rows=835540 width=24)
-> Index Scan using cdrs_connections20_i_call on cdrs_connections20 v (cost=0.00..104175.88 rows=1638302 width=24)
-> Index Scan using cdrs_connections21_i_call on cdrs_connections21 v (cost=0.00..232173.00 rows=1859055 width=24)
-> Index Scan using cdrs_connections22_i_call on cdrs_connections22 v (cost=0.00..99680.31 rows=1549844 width=24)
-> Index Scan using cdrs_connections23_i_call on cdrs_connections23 v (cost=0.00..913103.99 rows=1597071 width=24)
-> Index Scan using cdrs_connections24_i_call on cdrs_connections24 v (cost=0.00..151771.48 rows=1547203 width=24)
-> Index Scan using cdrs_connections25_i_call on cdrs_connections25 v (cost=0.00..48.24 rows=320 width=24)
-> Index Scan using cdrs_connections26_i_call on cdrs_connections26 v (cost=0.00..94067.11 rows=1472598 width=24)
-> Index Scan using cdrs_connections27_i_call on cdrs_connections27 v (cost=0.00..110525.50 rows=1083587 width=24)
-> Index Scan using cdrs_connections28_i_call on cdrs_connections28 v (cost=0.00..352381.02 rows=1068230 width=24)
-> Index Scan using cdrs_connections29_i_call on cdrs_connections29 v (cost=0.00..78430.93 rows=1234409 width=24)
-> Index Scan using cdrs_connections30_i_call on cdrs_connections30 v (cost=0.00..44659.37 rows=696125 width=24)
-> Index Scan using connections_pkey on connections con (cost=0.00..7.49 rows=1 width=52)
Index Cond: (con.i_connection = v.i_connection)
-> Index Scan using vendors_pkey on vendors vn (cost=0.00..20.27 rows=1 width=25)
Index Cond: (vn.i_vendor = con.i_vendor)
-> Append (cost=0.00..378.91 rows=61 width=43)
-> Index Scan using cdrs_i_call on cdrs c (cost=0.00..3.87 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs1_i_call on cdrs1 c (cost=0.00..8.32 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs2_i_call on cdrs2 c (cost=0.00..8.32 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs3_i_call on cdrs3 c (cost=0.00..8.38 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs4_i_call on cdrs4 c (cost=0.00..8.45 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs5_i_call on cdrs5 c (cost=0.00..8.42 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs6_i_call on cdrs6 c (cost=0.00..8.43 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs7_i_call on cdrs7 c (cost=0.00..8.48 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs8_i_call on cdrs8 c (cost=0.00..8.44 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs9_i_call on cdrs9 c (cost=0.00..2.27 rows=1 width=38)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs10_i_call on cdrs10 c (cost=0.00..8.45 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs11_i_call on cdrs11 c (cost=0.00..8.44 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs12_i_call on cdrs12 c (cost=0.00..8.32 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs13_i_call on cdrs13 c (cost=0.00..3.87 rows=1 width=38)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs14_i_call on cdrs14 c (cost=0.00..8.32 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs15_i_call on cdrs15 c (cost=0.00..8.31 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs16_i_call on cdrs16 c (cost=0.00..8.31 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs17_i_call on cdrs17 c (cost=0.00..8.32 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs18_i_call on cdrs18 c (cost=0.00..8.32 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs19_i_call on cdrs19 c (cost=0.00..8.36 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs20_i_call on cdrs20 c (cost=0.00..8.48 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs21_i_call on cdrs21 c (cost=0.00..8.51 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs22_i_call on cdrs22 c (cost=0.00..8.47 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs23_i_call on cdrs23 c (cost=0.00..8.47 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs24_i_call on cdrs24 c (cost=0.00..8.47 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs25_i_call on cdrs25 c (cost=0.00..3.87 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs26_i_call on cdrs26 c (cost=0.00..8.49 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs27_i_call on cdrs27 c (cost=0.00..8.42 rows=1 width=37)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs28_i_call on cdrs28 c (cost=0.00..8.41 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs29_i_call on cdrs29 c (cost=0.00..8.43 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Index Scan using cdrs30_i_call on cdrs30 c (cost=0.00..8.35 rows=1 width=36)
Index Cond: (c.i_call = v.i_call)
Filter: (c.i_cdr > 39726118)
-> Hash (cost=3001.41..3001.41 rows=30944 width=25)
-> Index Scan using accounts_i_customer on accounts a (cost=0.00..3001.41 rows=30944 width=25)
-> Index Scan using customers_pkey on customers cs (cost=0.00..2.27 rows=1 width=17)
Index Cond: (cs.i_customer = a.i_customer)
-> Append (cost=0.00..249.41 rows=31 width=16)
-> Index Scan using calls_pkey on calls ca (cost=0.00..3.87 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls1_pkey on calls1 ca (cost=0.00..8.42 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls2_pkey on calls2 ca (cost=0.00..8.42 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls3_pkey on calls3 ca (cost=0.00..8.63 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls4_pkey on calls4 ca (cost=0.00..9.07 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls5_pkey on calls5 ca (cost=0.00..8.84 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls6_pkey on calls6 ca (cost=0.00..8.90 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls7_pkey on calls7 ca (cost=0.00..8.95 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls8_pkey on calls8 ca (cost=0.00..8.65 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls9_pkey on calls9 ca (cost=0.00..3.87 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls10_pkey on calls10 ca (cost=0.00..8.78 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls11_pkey on calls11 ca (cost=0.00..8.75 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls12_pkey on calls12 ca (cost=0.00..8.40 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls13_pkey on calls13 ca (cost=0.00..3.87 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls14_pkey on calls14 ca (cost=0.00..8.40 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls15_pkey on calls15 ca (cost=0.00..8.42 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls16_pkey on calls16 ca (cost=0.00..8.39 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls17_pkey on calls17 ca (cost=0.00..8.40 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls18_pkey on calls18 ca (cost=0.00..8.40 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls19_pkey on calls19 ca (cost=0.00..8.53 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls20_pkey on calls20 ca (cost=0.00..8.78 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls21_pkey on calls21 ca (cost=0.00..8.84 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls22_pkey on calls22 ca (cost=0.00..8.78 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls23_pkey on calls23 ca (cost=0.00..8.79 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls24_pkey on calls24 ca (cost=0.00..8.74 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls25_pkey on calls25 ca (cost=0.00..3.87 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls26_pkey on calls26 ca (cost=0.00..9.45 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls27_pkey on calls27 ca (cost=0.00..8.56 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls28_pkey on calls28 ca (cost=0.00..8.60 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls29_pkey on calls29 ca (cost=0.00..8.60 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
-> Index Scan using calls30_pkey on calls30 ca (cost=0.00..8.44 rows=1 width=16)
Index Cond: (ca.i_call = c.i_call)
(326 rows)
暗示：
我不知道确切原因，但是当我使用给定查询创建视图时没有最后两个表连接和供应商然后加入这个视图与剩余表查询工作得很好。
解决方案：我通过改变加入顺序解决了这个问题。从：
select c.i_cdr, v.i_cdrs_connection, c.i_call,
cs.name AS customer_name, a.username AS client_name_id,
con.name AS connection_name, vn.name AS vendor_name_id,
ca.setup_time,
c.remote_ip AS c_remote_ip_id, con.destination AS v_remote_ip_id
FROM cdrs c
JOIN Calls ca using (i_call)
JOIN cdrs_connections v using (i_call)
JOIN accounts a using(i_account)
JOIN customers cs using (i_customer)
JOIN connections con using(i_connection)
JOIN vendors vn using (i_vendor)
where i_cdr>397233018
到：
select c.i_cdr, v.i_cdrs_connection, c.i_call,
cs.name AS customer_name, a.username AS client_name_id,
con.name AS connection_name, vn.name AS vendor_name_id,
ca.setup_time,
c.remote_ip AS c_remote_ip_id, con.destination AS v_remote_ip_id
FROM cdrs c
JOIN accounts a using(i_account)
JOIN customers cs using (i_customer)
JOIN Calls ca using (i_call)
JOIN cdrs_connections v using (i_call)
JOIN connections con using(i_connection)
JOIN vendors vn using (i_vendor)
where i_cdr>397233018
这是因为 cdrs 表链接到accounts 表，而accounts 表又连接到customers 表。而 vendor 表通过连接表连接到 cdrs_connections。因此，通过按顺序放置这些表来删除循环。现在响应时间真的很好。