Thread
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Re: Slow performance
sivapostgres@yahoo.com <sivapostgres@yahoo.com> — 2024-07-26T05:30:23Z
Hello,Using PG 11.11, One PG Cluster, Windows 2019 Server Standard, Two databases with identical data. 1. First DB: client_db 2. Second DB: client_test Took backup (pg_dump) of first database (client_db) and restored the database as second database (client_test). Query: Select a.examname, a.registrationnumber, b.studentname, d.departmentname, e.levelname, a.subjectcode, c.subjectname, b.regular, a.semester, a.dummynumber, p.semester as curr_sem, a.internalmark, a.externalmark, a.result, coalesce((a.internalmark + a.externalmark),0) as total, a.absent, a.malpractice, c.maxinternalmark, f.noofsemester, a.examstudentstatus, Case When a.result = 'P' Then 'P' Else Case When a.result = 'F' and a.malpractice = 'Y' and a.examstudentstatus is null Then 'M' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'R' Then 'R.C' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'S' Then 'S.L' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'F' Then 'N.P' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'W' Then 'W.H' Else 'RA' End End End End End End as res, Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)) as course, a.revaluation, m.absent as int_abs, n.companyname, n.companydescription, m.totalmark as int_mark, q.addressone, q.addresstwo, Case When a.semester > f.noofsemester Then 'PRIVATE' When a.semester <= f.noofsemester and a.semester in (1,2) Then 'I - Year' When a.semester <= f.noofsemester and a.semester in (3,4) Then 'II - Year' When a.semester <= f.noofsemester and a.semester in (5,6) Then 'III - Year' End as studyr, c.subjectserialno, p.regulararrear From cl_student_exam_subject a Join cl_student_name b On b.companycode = a.companycode And b.registrationnumber = a.registrationnumber Join cl_subject c On c.companycode = a.companycode And c.subjectcode = a.subjectcode Join cl_department_header d On d.departmentheaderpk = b.departmentheaderfk Join cl_level e On e.levelpk = b.Levelfk Join cl_department_detail f On f.departmentheaderfk = b.departmentheaderfk And f.levelfk = b.levelfk Left Outer Join cl_student_internal_mark m On m.companycode = a.companycode And m.registrationnumber = a.registrationnumber And m.subjectcode = a.subjectcode And m.departmentheaderfk = b.departmentheaderfk And m.levelfk = b.levelfk And m.Regular = b.Regular Join co_company n On n.companycode = a.companycode Join cl_student_semester_subject p On p.companycode = a.companycode And p.examheaderfk = a.examheaderfk And p.subjectcode = a.subjectcode And p.registrationnumber = a.registrationnumber And p.semester = a.semester Join co_company_branch q On n.companycode = a.companycode Where a.companycode = '100' And a.examheaderfk = 'BA80952CFF8F4E1C3F9F44B62ED9BF37' And (a.examstudentstatus is null or a.examstudentstatus in ('R', 'S', 'W')) And b.departmentheaderfk in ('04DF8BD89D0844DD4D8AA151EFB28657') And b.levelfk in ('37A9BEC2638844FFD5B1422D83E70EF3') And b.status = 'A' Order By Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)), Case When a.semester > f.noofsemester Then 'PRIVATE' When a.semester <= f.noofsemester and a.semester in (1,2) Then 'I - Year' When a.semester <= f.noofsemester and a.semester in (3,4) Then 'II - Year' When a.semester <= f.noofsemester and a.semester in (5,6) Then 'III - Year' End, a.registrationnumber, b.regular, p.semester desc, c.subjectserialno, Case When c.subjectcategory = 'T' Then 1 When c.subjectcategory = 'P' Then 2 When c.subjectcategory = 'D' Then 3 When c.subjectcategory = 'V' Then 4 When c.subjectcategory = 'J' Then 5 End, c.ancillary, Case When Substring(a.subjectcode, 6, 1) = 'C' Then 1 When Substring(a.subjectcode, 6, 1) = 'S' Then 2 When Substring(a.subjectcode, 6, 1) = 'A' Then 3 When Substring(a.subjectcode, 6, 1) = 'E' Then 4 Else 5 End, a.subjectcode Explain Analyze of DB 1 (client_db) :"Sort (cost=2862.35..2862.36 rows=1 width=1088) (actual time=451671.464..451671.495 rows=326 loops=1)"" Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 END), a.subjectcode"" Sort Method: quicksort Memory: 193kB"" -> Nested Loop (cost=2.36..2862.34 rows=1 width=1088) (actual time=57829.857..451662.727 rows=326 loops=1)"" -> Nested Loop (cost=2.36..2861.23 rows=1 width=686) (actual time=57829.829..451658.085 rows=326 loops=1)"" Join Filter: (((b.registrationnumber)::text = (p.registrationnumber)::text) AND ((c.subjectcode)::text = (p.subjectcode)::text) AND (a.semester = p.semester))"" Rows Removed by Join Filter: 13614738"" -> Index Scan using ""cl_student_semester_subject_IX3"" on cl_student_semester_subject p (cost=0.55..8.57 rows=1 width=60) (actual time=0.033..55.702 rows=41764 loops=1)"" Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))"" -> Nested Loop Left Join (cost=1.81..2848.39 rows=244 width=735) (actual time=0.068..10.768 rows=326 loops=41764)"" Join Filter: (((m.departmentheaderfk)::text = (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) AND (m.regular = b.regular))"" -> Nested Loop (cost=1.39..2135.32 rows=244 width=795) (actual time=0.053..6.723 rows=326 loops=41764)"" -> Nested Loop (cost=1.11..2058.12 rows=244 width=746) (actual time=0.045..4.299 rows=326 loops=41764)"" -> Nested Loop (cost=0.68..312.80 rows=172 width=699) (actual time=0.029..0.338 rows=313 loops=41764)"" -> Seq Scan on co_company n (cost=0.00..1.01 rows=1 width=394) (actual time=0.001..0.001 rows=1 loops=41764)"" Filter: ((companycode)::text = '100'::text)"" -> Nested Loop (cost=0.68..310.07 rows=172 width=305) (actual time=0.025..0.282 rows=313 loops=41764)"" -> Nested Loop (cost=0.27..10.70 rows=1 width=438) (actual time=0.013..0.019 rows=1 loops=41764)"" -> Nested Loop (cost=0.27..9.60 rows=1 width=278) (actual time=0.009..0.013 rows=1 loops=41764)"" -> Seq Scan on cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual time=0.002..0.004 rows=1 loops=41764)"" Filter: ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)"" Rows Removed by Filter: 23"" -> Index Scan using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 rows=1 width=78) (actual time=0.007..0.007 rows=1 loops=41764)"" Index Cond: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Seq Scan on cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.001..0.003 rows=1 loops=41764)"" Filter: ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)"" Rows Removed by Filter: 6"" -> Index Scan using cl_student_name_ix4 on cl_student_name b (cost=0.41..297.65 rows=172 width=97) (actual time=0.011..0.165 rows=313 loops=41764)"" Index Cond: (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))"" -> Index Scan using ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a (cost=0.42..10.13 rows=2 width=89) (actual time=0.012..0.012 rows=1 loops=13072132)"" Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = (b.registrationnumber)::text))"" Filter: ((examstudentstatus IS NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))"" -> Index Scan using cl_subject_ix3 on cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.007..0.007 rows=1 loops=13615064)"" Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))"" -> Index Scan using ""cl_student_internal_mark_IX"" on cl_student_internal_mark m (cost=0.42..2.90 rows=1 width=97) (actual time=0.011..0.011 rows=1 loops=13615064)"" Index Cond: (((companycode)::text = (a.companycode)::text) AND ((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text))"" Filter: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 width=276) (actual time=0.001..0.001 rows=1 loops=326)""Planning Time: 15.936 ms""Execution Time: 451672.059 ms" Explain Analyze of Second DB (client_test)"Sort (cost=3454.91..3454.92 rows=1 width=1088) (actual time=19.120..19.137 rows=326 loops=1)"" Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 END), a.subjectcode"" Sort Method: quicksort Memory: 193kB"" -> Nested Loop (cost=2.23..3454.90 rows=1 width=1088) (actual time=0.319..14.984 rows=326 loops=1)"" -> Nested Loop (cost=2.23..3453.78 rows=1 width=686) (actual time=0.298..13.691 rows=326 loops=1)"" Join Filter: (((b.registrationnumber)::text = (p.registrationnumber)::text) AND ((c.subjectcode)::text = (p.subjectcode)::text))"" -> Nested Loop Left Join (cost=1.81..2739.81 rows=230 width=735) (actual time=0.259..9.970 rows=326 loops=1)"" Join Filter: (((m.departmentheaderfk)::text = (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) AND (m.regular = b.regular))"" -> Nested Loop (cost=1.39..2060.47 rows=230 width=795) (actual time=0.233..6.232 rows=326 loops=1)"" -> Nested Loop (cost=1.11..1987.62 rows=230 width=746) (actual time=0.211..3.955 rows=326 loops=1)"" -> Nested Loop (cost=0.68..299.78 rows=166 width=699) (actual time=0.118..0.393 rows=313 loops=1)"" -> Seq Scan on co_company n (cost=0.00..1.01 rows=1 width=394) (actual time=0.026..0.027 rows=1 loops=1)"" Filter: ((companycode)::text = '100'::text)"" -> Nested Loop (cost=0.68..297.11 rows=166 width=305) (actual time=0.091..0.316 rows=313 loops=1)"" -> Nested Loop (cost=0.27..10.70 rows=1 width=438) (actual time=0.041..0.048 rows=1 loops=1)"" -> Nested Loop (cost=0.27..9.60 rows=1 width=278) (actual time=0.034..0.038 rows=1 loops=1)"" -> Seq Scan on cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual time=0.009..0.011 rows=1 loops=1)"" Filter: ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)"" Rows Removed by Filter: 23"" -> Index Scan using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 rows=1 width=78) (actual time=0.024..0.024 rows=1 loops=1)"" Index Cond: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Seq Scan on cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.006..0.008 rows=1 loops=1)"" Filter: ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)"" Rows Removed by Filter: 6"" -> Index Scan using cl_student_name_ix4 on cl_student_name b (cost=0.41..284.75 rows=166 width=97) (actual time=0.049..0.184 rows=313 loops=1)"" Index Cond: (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))"" -> Index Scan using ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a (cost=0.42..10.15 rows=2 width=89) (actual time=0.010..0.011 rows=1 loops=313)"" Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = (b.registrationnumber)::text))"" Filter: ((examstudentstatus IS NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))"" -> Index Scan using cl_subject_ix3 on cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.006..0.006 rows=1 loops=326)"" Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))"" -> Index Scan using ""cl_student_internal_mark_IX"" on cl_student_internal_mark m (cost=0.42..2.94 rows=1 width=97) (actual time=0.010..0.010 rows=1 loops=326)"" Index Cond: (((companycode)::text = (a.companycode)::text) AND ((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text))"" Filter: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Index Scan using ""cl_student_semester_subject_IX1"" on cl_student_semester_subject p (cost=0.42..3.09 rows=1 width=60) (actual time=0.010..0.010 rows=1 loops=326)"" Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text) AND (semester = a.semester))"" Filter: ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text)"" -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 width=276) (actual time=0.000..0.000 rows=1 loops=326)""Planning Time: 15.581 ms""Execution Time: 19.546 ms" The query when run against DB1 takes around 7 min 32 seconds.The same query when run against DB2 takes around 124 msec. Same computer, same PG cluster, same query.Why it takes so much time when run against DB1 (client_db)? Already executed vacuum against client_db database. Any help is really appreciated. Happiness Always BKR Sivaprakash -
Re: Slow performance
Muhammad Ikram <mmikram@gmail.com> — 2024-07-26T05:41:56Z
Hi, Could you perform diff on postgresql.conf file to see whether values are same for work_mem, shared_buffers, maintenance_work_mem and other related parameters? Regards, Ikram On Fri, Jul 26, 2024 at 10:31 AM sivapostgres@yahoo.com < sivapostgres@yahoo.com> wrote: > Hello, > Using PG 11.11, One PG Cluster, Windows 2019 Server Standard, Two > databases with identical data. > > 1. First DB: client_db > 2. Second DB: client_test > > Took backup (pg_dump) of first database (client_db) and restored the > database as second database (client_test). > > Query: > Select a.examname, a.registrationnumber, b.studentname, d.departmentname, > e.levelname, > a.subjectcode, c.subjectname, b.regular, a.semester, > a.dummynumber, p.semester as curr_sem, > a.internalmark, a.externalmark, a.result, coalesce((a.internalmark > + a.externalmark),0) as total, > a.absent, a.malpractice, c.maxinternalmark, f.noofsemester, > a.examstudentstatus, > Case When a.result = 'P' Then 'P' Else > Case When a.result = 'F' and a.malpractice = 'Y' and > a.examstudentstatus is null Then 'M' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'R' Then 'R.C' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'S' Then 'S.L' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'F' Then 'N.P' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'W' Then 'W.H' Else > 'RA' End End End End > End End as res, > Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)) as > course, > a.revaluation, m.absent as int_abs, n.companyname, > n.companydescription, > m.totalmark as int_mark, q.addressone, q.addresstwo, > Case When a.semester > f.noofsemester Then 'PRIVATE' > When a.semester <= f.noofsemester and a.semester in (1,2) > Then 'I - Year' > When a.semester <= f.noofsemester and a.semester in (3,4) > Then 'II - Year' > When a.semester <= f.noofsemester and a.semester in (5,6) > Then 'III - Year' End as studyr, > c.subjectserialno, p.regulararrear > From cl_student_exam_subject a > Join cl_student_name b > On b.companycode = a.companycode > And b.registrationnumber = a.registrationnumber > Join cl_subject c > On c.companycode = a.companycode > And c.subjectcode = a.subjectcode > Join cl_department_header d > On d.departmentheaderpk = b.departmentheaderfk > Join cl_level e > On e.levelpk = b.Levelfk > Join cl_department_detail f > On f.departmentheaderfk = b.departmentheaderfk > And f.levelfk = b.levelfk > Left Outer Join cl_student_internal_mark m > On m.companycode = a.companycode > And m.registrationnumber = a.registrationnumber > And m.subjectcode = a.subjectcode > And m.departmentheaderfk = b.departmentheaderfk > And m.levelfk = b.levelfk > And m.Regular = b.Regular > Join co_company n > On n.companycode = a.companycode > Join cl_student_semester_subject p > On p.companycode = a.companycode > And p.examheaderfk = a.examheaderfk > And p.subjectcode = a.subjectcode > And p.registrationnumber = a.registrationnumber > And p.semester = a.semester > Join co_company_branch q > On n.companycode = a.companycode > Where a.companycode = '100' > And a.examheaderfk = 'BA80952CFF8F4E1C3F9F44B62ED9BF37' > And (a.examstudentstatus is null or a.examstudentstatus in ('R', 'S', > 'W')) > And b.departmentheaderfk in ('04DF8BD89D0844DD4D8AA151EFB28657') > And b.levelfk in ('37A9BEC2638844FFD5B1422D83E70EF3') > And b.status = 'A' > Order By Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)), > Case When a.semester > f.noofsemester Then 'PRIVATE' > When a.semester <= f.noofsemester and a.semester in (1,2) > Then 'I - Year' > When a.semester <= f.noofsemester and a.semester in (3,4) > Then 'II - Year' > When a.semester <= f.noofsemester and a.semester in (5,6) > Then 'III - Year' End, > a.registrationnumber, b.regular, p.semester desc, > c.subjectserialno, > Case When c.subjectcategory = 'T' Then 1 > When c.subjectcategory = 'P' Then 2 > When c.subjectcategory = 'D' Then 3 > When c.subjectcategory = 'V' Then 4 > When c.subjectcategory = 'J' Then 5 End, > c.ancillary, > Case When Substring(a.subjectcode, 6, 1) = 'C' Then 1 > When Substring(a.subjectcode, 6, 1) = 'S' Then 2 > When Substring(a.subjectcode, 6, 1) = 'A' Then 3 > When Substring(a.subjectcode, 6, 1) = 'E' Then 4 Else 5 End, > a.subjectcode > > > Explain Analyze of DB 1 (client_db) : > "Sort (cost=2862.35..2862.36 rows=1 width=1088) (actual > time=451671.464..451671.495 rows=326 loops=1)" > " Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', > rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) > THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = > ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= > f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - > Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY > ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), > a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE > WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = > 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN > (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = > 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 > END), a.subjectcode" > " Sort Method: quicksort Memory: 193kB" > " -> Nested Loop (cost=2.36..2862.34 rows=1 width=1088) (actual > time=57829.857..451662.727 rows=326 loops=1)" > " -> Nested Loop (cost=2.36..2861.23 rows=1 width=686) (actual > time=57829.829..451658.085 rows=326 loops=1)" > " Join Filter: (((b.registrationnumber)::text = > (p.registrationnumber)::text) AND ((c.subjectcode)::text = > (p.subjectcode)::text) AND (a.semester = p.semester))" > " Rows Removed by Join Filter: 13614738" > " -> Index Scan using ""cl_student_semester_subject_IX3"" on > cl_student_semester_subject p (cost=0.55..8.57 rows=1 width=60) (actual > time=0.033..55.702 rows=41764 loops=1)" > " Index Cond: (((companycode)::text = '100'::text) AND > ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))" > " -> Nested Loop Left Join (cost=1.81..2848.39 rows=244 > width=735) (actual time=0.068..10.768 rows=326 loops=41764)" > " Join Filter: (((m.departmentheaderfk)::text = > (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) > AND (m.regular = b.regular))" > " -> Nested Loop (cost=1.39..2135.32 rows=244 > width=795) (actual time=0.053..6.723 rows=326 loops=41764)" > " -> Nested Loop (cost=1.11..2058.12 rows=244 > width=746) (actual time=0.045..4.299 rows=326 loops=41764)" > " -> Nested Loop (cost=0.68..312.80 > rows=172 width=699) (actual time=0.029..0.338 rows=313 loops=41764)" > " -> Seq Scan on co_company n > (cost=0.00..1.01 rows=1 width=394) (actual time=0.001..0.001 rows=1 > loops=41764)" > " Filter: ((companycode)::text > = '100'::text)" > " -> Nested Loop (cost=0.68..310.07 > rows=172 width=305) (actual time=0.025..0.282 rows=313 loops=41764)" > " -> Nested Loop > (cost=0.27..10.70 rows=1 width=438) (actual time=0.013..0.019 rows=1 > loops=41764)" > " -> Nested Loop > (cost=0.27..9.60 rows=1 width=278) (actual time=0.009..0.013 rows=1 > loops=41764)" > " -> Seq Scan on > cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual > time=0.002..0.004 rows=1 loops=41764)" > " Filter: > ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)" > " Rows > Removed by Filter: 23" > " -> Index Scan > using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 > rows=1 width=78) (actual time=0.007..0.007 rows=1 loops=41764)" > " Index Cond: > (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) > AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Seq Scan on > cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.001..0.003 > rows=1 loops=41764)" > " Filter: > ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)" > " Rows Removed by > Filter: 6" > " -> Index Scan using > cl_student_name_ix4 on cl_student_name b (cost=0.41..297.65 rows=172 > width=97) (actual time=0.011..0.165 rows=313 loops=41764)" > " Index Cond: > (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))" > " -> Index Scan using > ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a > (cost=0.42..10.13 rows=2 width=89) (actual time=0.012..0.012 rows=1 > loops=13072132)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = > (b.registrationnumber)::text))" > " Filter: ((examstudentstatus IS > NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))" > " -> Index Scan using cl_subject_ix3 on > cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.007..0.007 > rows=1 loops=13615064)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))" > " -> Index Scan using ""cl_student_internal_mark_IX"" > on cl_student_internal_mark m (cost=0.42..2.90 rows=1 width=97) (actual > time=0.011..0.011 rows=1 loops=13615064)" > " Index Cond: (((companycode)::text = > (a.companycode)::text) AND ((companycode)::text = '100'::text) AND > ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text))" > " Filter: (((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 > width=276) (actual time=0.001..0.001 rows=1 loops=326)" > "Planning Time: 15.936 ms" > "Execution Time: 451672.059 ms" > > > > Explain Analyze of Second DB (client_test) > "Sort (cost=3454.91..3454.92 rows=1 width=1088) (actual > time=19.120..19.137 rows=326 loops=1)" > " Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', > rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) > THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = > ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= > f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - > Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY > ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), > a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE > WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = > 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN > (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = > 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 > END), a.subjectcode" > " Sort Method: quicksort Memory: 193kB" > " -> Nested Loop (cost=2.23..3454.90 rows=1 width=1088) (actual > time=0.319..14.984 rows=326 loops=1)" > " -> Nested Loop (cost=2.23..3453.78 rows=1 width=686) (actual > time=0.298..13.691 rows=326 loops=1)" > " Join Filter: (((b.registrationnumber)::text = > (p.registrationnumber)::text) AND ((c.subjectcode)::text = > (p.subjectcode)::text))" > " -> Nested Loop Left Join (cost=1.81..2739.81 rows=230 > width=735) (actual time=0.259..9.970 rows=326 loops=1)" > " Join Filter: (((m.departmentheaderfk)::text = > (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) > AND (m.regular = b.regular))" > " -> Nested Loop (cost=1.39..2060.47 rows=230 > width=795) (actual time=0.233..6.232 rows=326 loops=1)" > " -> Nested Loop (cost=1.11..1987.62 rows=230 > width=746) (actual time=0.211..3.955 rows=326 loops=1)" > " -> Nested Loop (cost=0.68..299.78 > rows=166 width=699) (actual time=0.118..0.393 rows=313 loops=1)" > " -> Seq Scan on co_company n > (cost=0.00..1.01 rows=1 width=394) (actual time=0.026..0.027 rows=1 > loops=1)" > " Filter: ((companycode)::text > = '100'::text)" > " -> Nested Loop (cost=0.68..297.11 > rows=166 width=305) (actual time=0.091..0.316 rows=313 loops=1)" > " -> Nested Loop > (cost=0.27..10.70 rows=1 width=438) (actual time=0.041..0.048 rows=1 > loops=1)" > " -> Nested Loop > (cost=0.27..9.60 rows=1 width=278) (actual time=0.034..0.038 rows=1 > loops=1)" > " -> Seq Scan on > cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual > time=0.009..0.011 rows=1 loops=1)" > " Filter: > ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)" > " Rows > Removed by Filter: 23" > " -> Index Scan > using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 > rows=1 width=78) (actual time=0.024..0.024 rows=1 loops=1)" > " Index Cond: > (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) > AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Seq Scan on > cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.006..0.008 > rows=1 loops=1)" > " Filter: > ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)" > " Rows Removed by > Filter: 6" > " -> Index Scan using > cl_student_name_ix4 on cl_student_name b (cost=0.41..284.75 rows=166 > width=97) (actual time=0.049..0.184 rows=313 loops=1)" > " Index Cond: > (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))" > " -> Index Scan using > ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a > (cost=0.42..10.15 rows=2 width=89) (actual time=0.010..0.011 rows=1 > loops=313)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = > (b.registrationnumber)::text))" > " Filter: ((examstudentstatus IS > NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))" > " -> Index Scan using cl_subject_ix3 on > cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.006..0.006 > rows=1 loops=326)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))" > " -> Index Scan using ""cl_student_internal_mark_IX"" > on cl_student_internal_mark m (cost=0.42..2.94 rows=1 width=97) (actual > time=0.010..0.010 rows=1 loops=326)" > " Index Cond: (((companycode)::text = > (a.companycode)::text) AND ((companycode)::text = '100'::text) AND > ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text))" > " Filter: (((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Index Scan using ""cl_student_semester_subject_IX1"" on > cl_student_semester_subject p (cost=0.42..3.09 rows=1 width=60) (actual > time=0.010..0.010 rows=1 loops=326)" > " Index Cond: (((companycode)::text = '100'::text) AND > ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text) AND (semester = > a.semester))" > " Filter: ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text)" > " -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 > width=276) (actual time=0.000..0.000 rows=1 loops=326)" > "Planning Time: 15.581 ms" > "Execution Time: 19.546 ms" > > > The query when run against DB1 takes around 7 min 32 seconds. > The same query when run against DB2 takes around 124 msec. > > Same computer, same PG cluster, same query. > Why it takes so much time when run against DB1 (client_db)? > > Already executed vacuum against client_db database. > > Any help is really appreciated. > > Happiness Always > BKR Sivaprakash > > -- Muhammad Ikram -
Re: Slow performance
sivapostgres@yahoo.com <sivapostgres@yahoo.com> — 2024-07-26T06:05:38Z
I've only one instance of PG in that server. Means only one postgresql.conf for both databases. On Friday, 26 July, 2024 at 11:12:34 am IST, Muhammad Ikram <mmikram@gmail.com> wrote: Hi, Could you perform diff on postgresql.conf file to see whether values are same for work_mem, shared_buffers, maintenance_work_mem and other related parameters? Regards,Ikram On Fri, Jul 26, 2024 at 10:31 AM sivapostgres@yahoo.com <sivapostgres@yahoo.com> wrote: Hello,Using PG 11.11, One PG Cluster, Windows 2019 Server Standard, Two databases with identical data. 1. First DB: client_db 2. Second DB: client_test Took backup (pg_dump) of first database (client_db) and restored the database as second database (client_test). Query: Select a.examname, a.registrationnumber, b.studentname, d.departmentname, e.levelname, a.subjectcode, c.subjectname, b.regular, a.semester, a.dummynumber, p.semester as curr_sem, a.internalmark, a.externalmark, a.result, coalesce((a.internalmark + a.externalmark),0) as total, a.absent, a.malpractice, c.maxinternalmark, f.noofsemester, a.examstudentstatus, Case When a.result = 'P' Then 'P' Else Case When a.result = 'F' and a.malpractice = 'Y' and a.examstudentstatus is null Then 'M' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'R' Then 'R.C' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'S' Then 'S.L' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'F' Then 'N.P' Else Case When a.result = 'F' and a.absent = 'Y' and a.examstudentstatus = 'W' Then 'W.H' Else 'RA' End End End End End End as res, Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)) as course, a.revaluation, m.absent as int_abs, n.companyname, n.companydescription, m.totalmark as int_mark, q.addressone, q.addresstwo, Case When a.semester > f.noofsemester Then 'PRIVATE' When a.semester <= f.noofsemester and a.semester in (1,2) Then 'I - Year' When a.semester <= f.noofsemester and a.semester in (3,4) Then 'II - Year' When a.semester <= f.noofsemester and a.semester in (5,6) Then 'III - Year' End as studyr, c.subjectserialno, p.regulararrear From cl_student_exam_subject a Join cl_student_name b On b.companycode = a.companycode And b.registrationnumber = a.registrationnumber Join cl_subject c On c.companycode = a.companycode And c.subjectcode = a.subjectcode Join cl_department_header d On d.departmentheaderpk = b.departmentheaderfk Join cl_level e On e.levelpk = b.Levelfk Join cl_department_detail f On f.departmentheaderfk = b.departmentheaderfk And f.levelfk = b.levelfk Left Outer Join cl_student_internal_mark m On m.companycode = a.companycode And m.registrationnumber = a.registrationnumber And m.subjectcode = a.subjectcode And m.departmentheaderfk = b.departmentheaderfk And m.levelfk = b.levelfk And m.Regular = b.Regular Join co_company n On n.companycode = a.companycode Join cl_student_semester_subject p On p.companycode = a.companycode And p.examheaderfk = a.examheaderfk And p.subjectcode = a.subjectcode And p.registrationnumber = a.registrationnumber And p.semester = a.semester Join co_company_branch q On n.companycode = a.companycode Where a.companycode = '100' And a.examheaderfk = 'BA80952CFF8F4E1C3F9F44B62ED9BF37' And (a.examstudentstatus is null or a.examstudentstatus in ('R', 'S', 'W')) And b.departmentheaderfk in ('04DF8BD89D0844DD4D8AA151EFB28657') And b.levelfk in ('37A9BEC2638844FFD5B1422D83E70EF3') And b.status = 'A' Order By Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)), Case When a.semester > f.noofsemester Then 'PRIVATE' When a.semester <= f.noofsemester and a.semester in (1,2) Then 'I - Year' When a.semester <= f.noofsemester and a.semester in (3,4) Then 'II - Year' When a.semester <= f.noofsemester and a.semester in (5,6) Then 'III - Year' End, a.registrationnumber, b.regular, p.semester desc, c.subjectserialno, Case When c.subjectcategory = 'T' Then 1 When c.subjectcategory = 'P' Then 2 When c.subjectcategory = 'D' Then 3 When c.subjectcategory = 'V' Then 4 When c.subjectcategory = 'J' Then 5 End, c.ancillary, Case When Substring(a.subjectcode, 6, 1) = 'C' Then 1 When Substring(a.subjectcode, 6, 1) = 'S' Then 2 When Substring(a.subjectcode, 6, 1) = 'A' Then 3 When Substring(a.subjectcode, 6, 1) = 'E' Then 4 Else 5 End, a.subjectcode Explain Analyze of DB 1 (client_db) :"Sort (cost=2862.35..2862.36 rows=1 width=1088) (actual time=451671.464..451671.495 rows=326 loops=1)"" Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 END), a.subjectcode"" Sort Method: quicksort Memory: 193kB"" -> Nested Loop (cost=2.36..2862.34 rows=1 width=1088) (actual time=57829.857..451662.727 rows=326 loops=1)"" -> Nested Loop (cost=2.36..2861.23 rows=1 width=686) (actual time=57829.829..451658.085 rows=326 loops=1)"" Join Filter: (((b.registrationnumber)::text = (p.registrationnumber)::text) AND ((c.subjectcode)::text = (p.subjectcode)::text) AND (a.semester = p.semester))"" Rows Removed by Join Filter: 13614738"" -> Index Scan using ""cl_student_semester_subject_IX3"" on cl_student_semester_subject p (cost=0.55..8.57 rows=1 width=60) (actual time=0.033..55.702 rows=41764 loops=1)"" Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))"" -> Nested Loop Left Join (cost=1.81..2848.39 rows=244 width=735) (actual time=0.068..10.768 rows=326 loops=41764)"" Join Filter: (((m.departmentheaderfk)::text = (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) AND (m.regular = b.regular))"" -> Nested Loop (cost=1.39..2135.32 rows=244 width=795) (actual time=0.053..6.723 rows=326 loops=41764)"" -> Nested Loop (cost=1.11..2058.12 rows=244 width=746) (actual time=0.045..4.299 rows=326 loops=41764)"" -> Nested Loop (cost=0.68..312.80 rows=172 width=699) (actual time=0.029..0.338 rows=313 loops=41764)"" -> Seq Scan on co_company n (cost=0.00..1.01 rows=1 width=394) (actual time=0.001..0.001 rows=1 loops=41764)"" Filter: ((companycode)::text = '100'::text)"" -> Nested Loop (cost=0.68..310.07 rows=172 width=305) (actual time=0.025..0.282 rows=313 loops=41764)"" -> Nested Loop (cost=0.27..10.70 rows=1 width=438) (actual time=0.013..0.019 rows=1 loops=41764)"" -> Nested Loop (cost=0.27..9.60 rows=1 width=278) (actual time=0.009..0.013 rows=1 loops=41764)"" -> Seq Scan on cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual time=0.002..0.004 rows=1 loops=41764)"" Filter: ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)"" Rows Removed by Filter: 23"" -> Index Scan using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 rows=1 width=78) (actual time=0.007..0.007 rows=1 loops=41764)"" Index Cond: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Seq Scan on cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.001..0.003 rows=1 loops=41764)"" Filter: ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)"" Rows Removed by Filter: 6"" -> Index Scan using cl_student_name_ix4 on cl_student_name b (cost=0.41..297.65 rows=172 width=97) (actual time=0.011..0.165 rows=313 loops=41764)"" Index Cond: (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))"" -> Index Scan using ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a (cost=0.42..10.13 rows=2 width=89) (actual time=0.012..0.012 rows=1 loops=13072132)"" Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = (b.registrationnumber)::text))"" Filter: ((examstudentstatus IS NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))"" -> Index Scan using cl_subject_ix3 on cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.007..0.007 rows=1 loops=13615064)"" Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))"" -> Index Scan using ""cl_student_internal_mark_IX"" on cl_student_internal_mark m (cost=0.42..2.90 rows=1 width=97) (actual time=0.011..0.011 rows=1 loops=13615064)"" Index Cond: (((companycode)::text = (a.companycode)::text) AND ((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text))"" Filter: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 width=276) (actual time=0.001..0.001 rows=1 loops=326)""Planning Time: 15.936 ms""Execution Time: 451672.059 ms" Explain Analyze of Second DB (client_test)"Sort (cost=3454.91..3454.92 rows=1 width=1088) (actual time=19.120..19.137 rows=326 loops=1)"" Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 END), a.subjectcode"" Sort Method: quicksort Memory: 193kB"" -> Nested Loop (cost=2.23..3454.90 rows=1 width=1088) (actual time=0.319..14.984 rows=326 loops=1)"" -> Nested Loop (cost=2.23..3453.78 rows=1 width=686) (actual time=0.298..13.691 rows=326 loops=1)"" Join Filter: (((b.registrationnumber)::text = (p.registrationnumber)::text) AND ((c.subjectcode)::text = (p.subjectcode)::text))"" -> Nested Loop Left Join (cost=1.81..2739.81 rows=230 width=735) (actual time=0.259..9.970 rows=326 loops=1)"" Join Filter: (((m.departmentheaderfk)::text = (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) AND (m.regular = b.regular))"" -> Nested Loop (cost=1.39..2060.47 rows=230 width=795) (actual time=0.233..6.232 rows=326 loops=1)"" -> Nested Loop (cost=1.11..1987.62 rows=230 width=746) (actual time=0.211..3.955 rows=326 loops=1)"" -> Nested Loop (cost=0.68..299.78 rows=166 width=699) (actual time=0.118..0.393 rows=313 loops=1)"" -> Seq Scan on co_company n (cost=0.00..1.01 rows=1 width=394) (actual time=0.026..0.027 rows=1 loops=1)"" Filter: ((companycode)::text = '100'::text)"" -> Nested Loop (cost=0.68..297.11 rows=166 width=305) (actual time=0.091..0.316 rows=313 loops=1)"" -> Nested Loop (cost=0.27..10.70 rows=1 width=438) (actual time=0.041..0.048 rows=1 loops=1)"" -> Nested Loop (cost=0.27..9.60 rows=1 width=278) (actual time=0.034..0.038 rows=1 loops=1)"" -> Seq Scan on cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual time=0.009..0.011 rows=1 loops=1)"" Filter: ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)"" Rows Removed by Filter: 23"" -> Index Scan using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 rows=1 width=78) (actual time=0.024..0.024 rows=1 loops=1)"" Index Cond: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Seq Scan on cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.006..0.008 rows=1 loops=1)"" Filter: ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)"" Rows Removed by Filter: 6"" -> Index Scan using cl_student_name_ix4 on cl_student_name b (cost=0.41..284.75 rows=166 width=97) (actual time=0.049..0.184 rows=313 loops=1)"" Index Cond: (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))"" -> Index Scan using ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a (cost=0.42..10.15 rows=2 width=89) (actual time=0.010..0.011 rows=1 loops=313)"" Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = (b.registrationnumber)::text))"" Filter: ((examstudentstatus IS NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))"" -> Index Scan using cl_subject_ix3 on cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.006..0.006 rows=1 loops=326)"" Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))"" -> Index Scan using ""cl_student_internal_mark_IX"" on cl_student_internal_mark m (cost=0.42..2.94 rows=1 width=97) (actual time=0.010..0.010 rows=1 loops=326)"" Index Cond: (((companycode)::text = (a.companycode)::text) AND ((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text))"" Filter: (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))"" -> Index Scan using ""cl_student_semester_subject_IX1"" on cl_student_semester_subject p (cost=0.42..3.09 rows=1 width=60) (actual time=0.010..0.010 rows=1 loops=326)"" Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text) AND (semester = a.semester))"" Filter: ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text)"" -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 width=276) (actual time=0.000..0.000 rows=1 loops=326)""Planning Time: 15.581 ms""Execution Time: 19.546 ms" The query when run against DB1 takes around 7 min 32 seconds.The same query when run against DB2 takes around 124 msec. Same computer, same PG cluster, same query.Why it takes so much time when run against DB1 (client_db)? Already executed vacuum against client_db database. Any help is really appreciated. Happiness Always BKR Sivaprakash -- Muhammad Ikram -
Re: Slow performance
Muhammad Ikram <mmikram@gmail.com> — 2024-07-26T06:15:42Z
Hi Again, I have not gone through your explain plans for both, will it be possible for you to take diff of the both plans. It will give some insight about how things are going and where the problem is. Alternatively I will suggest Reindex and execute ANALYZE command to regenerate stats . Regards, Ikram On Fri, Jul 26, 2024 at 11:05 AM sivapostgres@yahoo.com < sivapostgres@yahoo.com> wrote: > I've only one instance of PG in that server. Means only one > postgresql.conf for both databases. > > > On Friday, 26 July, 2024 at 11:12:34 am IST, Muhammad Ikram < > mmikram@gmail.com> wrote: > > > Hi, > > Could you perform diff on postgresql.conf file to see whether values are > same for work_mem, shared_buffers, maintenance_work_mem and other related > parameters? > > Regards, > Ikram > > > On Fri, Jul 26, 2024 at 10:31 AM sivapostgres@yahoo.com < > sivapostgres@yahoo.com> wrote: > > Hello, > Using PG 11.11, One PG Cluster, Windows 2019 Server Standard, Two > databases with identical data. > > 1. First DB: client_db > 2. Second DB: client_test > > Took backup (pg_dump) of first database (client_db) and restored the > database as second database (client_test). > > Query: > Select a.examname, a.registrationnumber, b.studentname, d.departmentname, > e.levelname, > a.subjectcode, c.subjectname, b.regular, a.semester, > a.dummynumber, p.semester as curr_sem, > a.internalmark, a.externalmark, a.result, coalesce((a.internalmark > + a.externalmark),0) as total, > a.absent, a.malpractice, c.maxinternalmark, f.noofsemester, > a.examstudentstatus, > Case When a.result = 'P' Then 'P' Else > Case When a.result = 'F' and a.malpractice = 'Y' and > a.examstudentstatus is null Then 'M' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'R' Then 'R.C' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'S' Then 'S.L' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'F' Then 'N.P' Else > Case When a.result = 'F' and a.absent = 'Y' and > a.examstudentstatus = 'W' Then 'W.H' Else > 'RA' End End End End > End End as res, > Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)) as > course, > a.revaluation, m.absent as int_abs, n.companyname, > n.companydescription, > m.totalmark as int_mark, q.addressone, q.addresstwo, > Case When a.semester > f.noofsemester Then 'PRIVATE' > When a.semester <= f.noofsemester and a.semester in (1,2) > Then 'I - Year' > When a.semester <= f.noofsemester and a.semester in (3,4) > Then 'II - Year' > When a.semester <= f.noofsemester and a.semester in (5,6) > Then 'III - Year' End as studyr, > c.subjectserialno, p.regulararrear > From cl_student_exam_subject a > Join cl_student_name b > On b.companycode = a.companycode > And b.registrationnumber = a.registrationnumber > Join cl_subject c > On c.companycode = a.companycode > And c.subjectcode = a.subjectcode > Join cl_department_header d > On d.departmentheaderpk = b.departmentheaderfk > Join cl_level e > On e.levelpk = b.Levelfk > Join cl_department_detail f > On f.departmentheaderfk = b.departmentheaderfk > And f.levelfk = b.levelfk > Left Outer Join cl_student_internal_mark m > On m.companycode = a.companycode > And m.registrationnumber = a.registrationnumber > And m.subjectcode = a.subjectcode > And m.departmentheaderfk = b.departmentheaderfk > And m.levelfk = b.levelfk > And m.Regular = b.Regular > Join co_company n > On n.companycode = a.companycode > Join cl_student_semester_subject p > On p.companycode = a.companycode > And p.examheaderfk = a.examheaderfk > And p.subjectcode = a.subjectcode > And p.registrationnumber = a.registrationnumber > And p.semester = a.semester > Join co_company_branch q > On n.companycode = a.companycode > Where a.companycode = '100' > And a.examheaderfk = 'BA80952CFF8F4E1C3F9F44B62ED9BF37' > And (a.examstudentstatus is null or a.examstudentstatus in ('R', 'S', > 'W')) > And b.departmentheaderfk in ('04DF8BD89D0844DD4D8AA151EFB28657') > And b.levelfk in ('37A9BEC2638844FFD5B1422D83E70EF3') > And b.status = 'A' > Order By Concat(RTrim(f.degreeawarded), ' ', RTrim(d.departmentname)), > Case When a.semester > f.noofsemester Then 'PRIVATE' > When a.semester <= f.noofsemester and a.semester in (1,2) > Then 'I - Year' > When a.semester <= f.noofsemester and a.semester in (3,4) > Then 'II - Year' > When a.semester <= f.noofsemester and a.semester in (5,6) > Then 'III - Year' End, > a.registrationnumber, b.regular, p.semester desc, > c.subjectserialno, > Case When c.subjectcategory = 'T' Then 1 > When c.subjectcategory = 'P' Then 2 > When c.subjectcategory = 'D' Then 3 > When c.subjectcategory = 'V' Then 4 > When c.subjectcategory = 'J' Then 5 End, > c.ancillary, > Case When Substring(a.subjectcode, 6, 1) = 'C' Then 1 > When Substring(a.subjectcode, 6, 1) = 'S' Then 2 > When Substring(a.subjectcode, 6, 1) = 'A' Then 3 > When Substring(a.subjectcode, 6, 1) = 'E' Then 4 Else 5 End, > a.subjectcode > > > Explain Analyze of DB 1 (client_db) : > "Sort (cost=2862.35..2862.36 rows=1 width=1088) (actual > time=451671.464..451671.495 rows=326 loops=1)" > " Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', > rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) > THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = > ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= > f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - > Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY > ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), > a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE > WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = > 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN > (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = > 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 > END), a.subjectcode" > " Sort Method: quicksort Memory: 193kB" > " -> Nested Loop (cost=2.36..2862.34 rows=1 width=1088) (actual > time=57829.857..451662.727 rows=326 loops=1)" > " -> Nested Loop (cost=2.36..2861.23 rows=1 width=686) (actual > time=57829.829..451658.085 rows=326 loops=1)" > " Join Filter: (((b.registrationnumber)::text = > (p.registrationnumber)::text) AND ((c.subjectcode)::text = > (p.subjectcode)::text) AND (a.semester = p.semester))" > " Rows Removed by Join Filter: 13614738" > " -> Index Scan using ""cl_student_semester_subject_IX3"" on > cl_student_semester_subject p (cost=0.55..8.57 rows=1 width=60) (actual > time=0.033..55.702 rows=41764 loops=1)" > " Index Cond: (((companycode)::text = '100'::text) AND > ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))" > " -> Nested Loop Left Join (cost=1.81..2848.39 rows=244 > width=735) (actual time=0.068..10.768 rows=326 loops=41764)" > " Join Filter: (((m.departmentheaderfk)::text = > (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) > AND (m.regular = b.regular))" > " -> Nested Loop (cost=1.39..2135.32 rows=244 > width=795) (actual time=0.053..6.723 rows=326 loops=41764)" > " -> Nested Loop (cost=1.11..2058.12 rows=244 > width=746) (actual time=0.045..4.299 rows=326 loops=41764)" > " -> Nested Loop (cost=0.68..312.80 > rows=172 width=699) (actual time=0.029..0.338 rows=313 loops=41764)" > " -> Seq Scan on co_company n > (cost=0.00..1.01 rows=1 width=394) (actual time=0.001..0.001 rows=1 > loops=41764)" > " Filter: ((companycode)::text > = '100'::text)" > " -> Nested Loop (cost=0.68..310.07 > rows=172 width=305) (actual time=0.025..0.282 rows=313 loops=41764)" > " -> Nested Loop > (cost=0.27..10.70 rows=1 width=438) (actual time=0.013..0.019 rows=1 > loops=41764)" > " -> Nested Loop > (cost=0.27..9.60 rows=1 width=278) (actual time=0.009..0.013 rows=1 > loops=41764)" > " -> Seq Scan on > cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual > time=0.002..0.004 rows=1 loops=41764)" > " Filter: > ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)" > " Rows > Removed by Filter: 23" > " -> Index Scan > using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 > rows=1 width=78) (actual time=0.007..0.007 rows=1 loops=41764)" > " Index Cond: > (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) > AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Seq Scan on > cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.001..0.003 > rows=1 loops=41764)" > " Filter: > ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)" > " Rows Removed by > Filter: 6" > " -> Index Scan using > cl_student_name_ix4 on cl_student_name b (cost=0.41..297.65 rows=172 > width=97) (actual time=0.011..0.165 rows=313 loops=41764)" > " Index Cond: > (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))" > " -> Index Scan using > ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a > (cost=0.42..10.13 rows=2 width=89) (actual time=0.012..0.012 rows=1 > loops=13072132)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = > (b.registrationnumber)::text))" > " Filter: ((examstudentstatus IS > NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))" > " -> Index Scan using cl_subject_ix3 on > cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.007..0.007 > rows=1 loops=13615064)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))" > " -> Index Scan using ""cl_student_internal_mark_IX"" > on cl_student_internal_mark m (cost=0.42..2.90 rows=1 width=97) (actual > time=0.011..0.011 rows=1 loops=13615064)" > " Index Cond: (((companycode)::text = > (a.companycode)::text) AND ((companycode)::text = '100'::text) AND > ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text))" > " Filter: (((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 > width=276) (actual time=0.001..0.001 rows=1 loops=326)" > "Planning Time: 15.936 ms" > "Execution Time: 451672.059 ms" > > > > Explain Analyze of Second DB (client_test) > "Sort (cost=3454.91..3454.92 rows=1 width=1088) (actual > time=19.120..19.137 rows=326 loops=1)" > " Sort Key: (concat(rtrim((f.degreeawarded)::text), ' ', > rtrim((d.departmentname)::text))), (CASE WHEN (a.semester > f.noofsemester) > THEN 'PRIVATE'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = > ANY ('{1,2}'::integer[]))) THEN 'I - Year'::text WHEN ((a.semester <= > f.noofsemester) AND (a.semester = ANY ('{3,4}'::integer[]))) THEN 'II - > Year'::text WHEN ((a.semester <= f.noofsemester) AND (a.semester = ANY > ('{5,6}'::integer[]))) THEN 'III - Year'::text ELSE NULL::text END), > a.registrationnumber, b.regular, a.semester DESC, c.subjectserialno, (CASE > WHEN (c.subjectcategory = 'T'::bpchar) THEN 1 WHEN (c.subjectcategory = > 'P'::bpchar) THEN 2 WHEN (c.subjectcategory = 'D'::bpchar) THEN 3 WHEN > (c.subjectcategory = 'V'::bpchar) THEN 4 WHEN (c.subjectcategory = > 'J'::bpchar) THEN 5 ELSE NULL::integer END), c.ancillary, (CASE WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'C'::text) THEN 1 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'S'::text) THEN 2 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'A'::text) THEN 3 WHEN > (""substring""((a.subjectcode)::text, 6, 1) = 'E'::text) THEN 4 ELSE 5 > END), a.subjectcode" > " Sort Method: quicksort Memory: 193kB" > " -> Nested Loop (cost=2.23..3454.90 rows=1 width=1088) (actual > time=0.319..14.984 rows=326 loops=1)" > " -> Nested Loop (cost=2.23..3453.78 rows=1 width=686) (actual > time=0.298..13.691 rows=326 loops=1)" > " Join Filter: (((b.registrationnumber)::text = > (p.registrationnumber)::text) AND ((c.subjectcode)::text = > (p.subjectcode)::text))" > " -> Nested Loop Left Join (cost=1.81..2739.81 rows=230 > width=735) (actual time=0.259..9.970 rows=326 loops=1)" > " Join Filter: (((m.departmentheaderfk)::text = > (b.departmentheaderfk)::text) AND ((m.levelfk)::text = (b.levelfk)::text) > AND (m.regular = b.regular))" > " -> Nested Loop (cost=1.39..2060.47 rows=230 > width=795) (actual time=0.233..6.232 rows=326 loops=1)" > " -> Nested Loop (cost=1.11..1987.62 rows=230 > width=746) (actual time=0.211..3.955 rows=326 loops=1)" > " -> Nested Loop (cost=0.68..299.78 > rows=166 width=699) (actual time=0.118..0.393 rows=313 loops=1)" > " -> Seq Scan on co_company n > (cost=0.00..1.01 rows=1 width=394) (actual time=0.026..0.027 rows=1 > loops=1)" > " Filter: ((companycode)::text > = '100'::text)" > " -> Nested Loop (cost=0.68..297.11 > rows=166 width=305) (actual time=0.091..0.316 rows=313 loops=1)" > " -> Nested Loop > (cost=0.27..10.70 rows=1 width=438) (actual time=0.041..0.048 rows=1 > loops=1)" > " -> Nested Loop > (cost=0.27..9.60 rows=1 width=278) (actual time=0.034..0.038 rows=1 > loops=1)" > " -> Seq Scan on > cl_department_header d (cost=0.00..1.30 rows=1 width=200) (actual > time=0.009..0.011 rows=1 loops=1)" > " Filter: > ((departmentheaderpk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text)" > " Rows > Removed by Filter: 23" > " -> Index Scan > using cl_department_detail_ix1 on cl_department_detail f (cost=0.27..8.29 > rows=1 width=78) (actual time=0.024..0.024 rows=1 loops=1)" > " Index Cond: > (((departmentheaderfk)::text = '04DF8BD89D0844DD4D8AA151EFB28657'::text) > AND ((levelfk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Seq Scan on > cl_level e (cost=0.00..1.09 rows=1 width=160) (actual time=0.006..0.008 > rows=1 loops=1)" > " Filter: > ((levelpk)::text = '37A9BEC2638844FFD5B1422D83E70EF3'::text)" > " Rows Removed by > Filter: 6" > " -> Index Scan using > cl_student_name_ix4 on cl_student_name b (cost=0.41..284.75 rows=166 > width=97) (actual time=0.049..0.184 rows=313 loops=1)" > " Index Cond: > (((companycode)::text = '100'::text) AND ((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text) AND (status = 'A'::bpchar))" > " -> Index Scan using > ""cl_student_exam_subject_IX1"" on cl_student_exam_subject a > (cost=0.42..10.15 rows=2 width=89) (actual time=0.010..0.011 rows=1 > loops=313)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text) AND ((registrationnumber)::text = > (b.registrationnumber)::text))" > " Filter: ((examstudentstatus IS > NULL) OR (examstudentstatus = ANY ('{R,S,W}'::bpchar[])))" > " -> Index Scan using cl_subject_ix3 on > cl_subject c (cost=0.28..0.32 rows=1 width=53) (actual time=0.006..0.006 > rows=1 loops=326)" > " Index Cond: (((companycode)::text = > '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text))" > " -> Index Scan using ""cl_student_internal_mark_IX"" > on cl_student_internal_mark m (cost=0.42..2.94 rows=1 width=97) (actual > time=0.010..0.010 rows=1 loops=326)" > " Index Cond: (((companycode)::text = > (a.companycode)::text) AND ((companycode)::text = '100'::text) AND > ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text))" > " Filter: (((departmentheaderfk)::text = > '04DF8BD89D0844DD4D8AA151EFB28657'::text) AND ((levelfk)::text = > '37A9BEC2638844FFD5B1422D83E70EF3'::text))" > " -> Index Scan using ""cl_student_semester_subject_IX1"" on > cl_student_semester_subject p (cost=0.42..3.09 rows=1 width=60) (actual > time=0.010..0.010 rows=1 loops=326)" > " Index Cond: (((companycode)::text = '100'::text) AND > ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text) AND (semester = > a.semester))" > " Filter: ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text)" > " -> Seq Scan on co_company_branch q (cost=0.00..1.01 rows=1 > width=276) (actual time=0.000..0.000 rows=1 loops=326)" > "Planning Time: 15.581 ms" > "Execution Time: 19.546 ms" > > > The query when run against DB1 takes around 7 min 32 seconds. > The same query when run against DB2 takes around 124 msec. > > Same computer, same PG cluster, same query. > Why it takes so much time when run against DB1 (client_db)? > > Already executed vacuum against client_db database. > > Any help is really appreciated. > > Happiness Always > BKR Sivaprakash > > > > -- > Muhammad Ikram > > -- Muhammad Ikram -
Re: Slow performance
Francisco Olarte <folarte@peoplecall.com> — 2024-07-26T07:54:43Z
Hello: On Fri, 26 Jul 2024 at 07:31, sivapostgres@yahoo.com <sivapostgres@yahoo.com> wrote: ... > Took backup (pg_dump) of first database (client_db) and restored the database as second database (client_test). ... > The query when run against DB1 takes around 7 min 32 seconds. > The same query when run against DB2 takes around 124 msec. > Same computer, same PG cluster, same query. > Why it takes so much time when run against DB1 (client_db)? Can be bad luck, but the usual suspect would be different databases. I assume db1 is quiescent on the tests ( as it seems the production database, no heavy querying concurrent with your tests ). Bear in mind restoring leaves the database similar to what a vacuum full will do, so it can differ a lot from the original. > Already executed vacuum against client_db database. I think you already have pointed out this, but IIRC you have not told us if you have ANALYZED any of the databases. This is important. Bad stats in any of them could make the planner choose a bad plan ( or, if you are unlucky, make it choose a bad one ). Also, did you vacuum verbose? where your tables well packed? ( bad vacuuming can lead to huge tables with a lot of free space, but I doubt this is your case, but everything has to be checked, we only know what you write us ). And now, not being an expert in tracing explain I see this in plan-db1: " Join Filter: (((b.registrationnumber)::text = (p.registrationnumber)::text) AND ((c.subjectcode)::text = (p.subjectcode)::text) AND (a.semester = p.semester))" " Rows Removed by Join Filter: 13614738" " -> Index Scan using ""cl_student_semester_subject_IX3"" on cl_student_semester_subject p (cost=0.55..8.57 rows=1 width=60) (actual time=0.033..55.702 rows=41764 loops=1)" " Index Cond: (((companycode)::text = '100'::text) AND ((examheaderfk)::text = 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))" Not an explain expert, but if i read correctly an index scan expecting 1 row recovers 41674, which hints at bad statistics ( or skewed data distribution and bad luck ) The plans are similar, but in the fast query cl_student_semester_subject is accessed using other index: " -> Index Scan using ""cl_student_semester_subject_IX1"" on cl_student_semester_subject p (cost=0.42..3.09 rows=1 width=60) (actual time=0.010..0.010 rows=1 loops=326)" " Index Cond: (((companycode)::text = '100'::text) AND ((subjectcode)::text = (a.subjectcode)::text) AND ((registrationnumber)::text = (a.registrationnumber)::text) AND (semester = a.semester))" Which seems much more selective and recovers just what it wants. I would start by analyzing ( and, if not too costly, reindexing ) that table. Francisco Olarte.
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Re: Slow performance
Fatih Sazan <fatihsazan01@gmail.com> — 2024-07-26T09:40:53Z
Hi Siva, pg_dump taken from client_db seems not to have transferred full data to client_test. When I examine the query plans, the rows scanned seem to be extremely different. For example, there is 1 row in cl_level table on client_test, while clined_db shows that around 300,000 records were scanned. My suggestion would be to check the data counts in the tables you moved with count(*). Francisco Olarte <folarte@peoplecall.com>, 26 Tem 2024 Cum, 10:55 tarihinde şunu yazdı: > Hello: > > On Fri, 26 Jul 2024 at 07:31, sivapostgres@yahoo.com > <sivapostgres@yahoo.com> wrote: > ... > > Took backup (pg_dump) of first database (client_db) and restored the > database as second database (client_test). > ... > > The query when run against DB1 takes around 7 min 32 seconds. > > The same query when run against DB2 takes around 124 msec. > > Same computer, same PG cluster, same query. > > Why it takes so much time when run against DB1 (client_db)? > > Can be bad luck, but the usual suspect would be different databases. > > I assume db1 is quiescent on the tests ( as it seems the production > database, no heavy querying concurrent with your tests ). > > Bear in mind restoring leaves the database similar to what a vacuum > full will do, so it can differ a lot from the original. > > > Already executed vacuum against client_db database. > > I think you already have pointed out this, but IIRC you have not told > us if you have ANALYZED any of the databases. This is important. Bad > stats in any of them could make the planner choose a bad plan ( or, if > you are unlucky, make it choose a bad one ). > > Also, did you vacuum verbose? where your tables well packed? ( bad > vacuuming can lead to huge tables with a lot of free space, but I > doubt this is your case, but everything has to be checked, we only > know what you write us ). > > And now, not being an expert in tracing explain I see this in plan-db1: > " Join Filter: (((b.registrationnumber)::text = > (p.registrationnumber)::text) AND ((c.subjectcode)::text = > (p.subjectcode)::text) AND (a.semester = p.semester))" > " Rows Removed by Join Filter: 13614738" > " -> Index Scan using > ""cl_student_semester_subject_IX3"" on cl_student_semester_subject p > (cost=0.55..8.57 rows=1 width=60) (actual time=0.033..55.702 > rows=41764 loops=1)" > " Index Cond: (((companycode)::text = '100'::text) > AND ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))" > > Not an explain expert, but if i read correctly an index scan expecting > 1 row recovers 41674, which hints at bad statistics ( or skewed data > distribution and bad luck ) > > The plans are similar, but in the fast query > cl_student_semester_subject is accessed using other index: > > " -> Index Scan using > ""cl_student_semester_subject_IX1"" on cl_student_semester_subject p > (cost=0.42..3.09 rows=1 width=60) (actual time=0.010..0.010 rows=1 > loops=326)" > " Index Cond: (((companycode)::text = '100'::text) > AND ((subjectcode)::text = (a.subjectcode)::text) AND > ((registrationnumber)::text = (a.registrationnumber)::text) AND > (semester = a.semester))" > > Which seems much more selective and recovers just what it wants. > > I would start by analyzing ( and, if not too costly, reindexing ) that > table. > > Francisco Olarte. > > >
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Re: Slow performance
David Rowley <dgrowleyml@gmail.com> — 2024-07-27T03:27:08Z
On Fri, 26 Jul 2024 at 19:55, Francisco Olarte <folarte@peoplecall.com> wrote: > " -> Index Scan using > ""cl_student_semester_subject_IX3"" on cl_student_semester_subject p > (cost=0.55..8.57 rows=1 width=60) (actual time=0.033..55.702 > rows=41764 loops=1)" > " Index Cond: (((companycode)::text = '100'::text) > AND ((examheaderfk)::text = > 'BA80952CFF8F4E1C3F9F44B62ED9BF37'::text))" > > Not an explain expert, but if i read correctly an index scan expecting > 1 row recovers 41674, which hints at bad statistics ( or skewed data > distribution and bad luck ) You have correctly identified the reason the poor plan was chosen. If that row estimate was anything higher than 1, that plan wouldn't be picked. If ANALYZE cl_student_semester_subject; does not fix the issue, then increasing the statistics targets with something like: alter table cl_student_semester_subject alter column companycode set (default_statistics_target = 1000); alter table cl_student_semester_subject alter column examheaderfk set (default_statistics_target = 1000); analyze cl_student_semester_subject; (Warning, additional statistics targets can slow down planning a little) or if that does not help and there's some correlation between those columns and/or the values in question, then maybe the following might help get a more accurate estimate: create statistics on companycode, examheaderfk from cl_student_semester_subject; analyze cl_student_semester_subject; David