Re: Join for the parent table will not leverage the index scan

I've seen a similar problem in v12, but this is different since it's a LIST
partition, and I use RANGE partitions.

The bottom line is that the query optimizer thinks it cheaper to
sequentially scan.  Is there an index on client_id which I missed?

On 8/16/21 10:25 PM, Shrikant Bhende wrote:
> Hi Ron,
>
> Thanks for the reply and clarification.
> Tables are getting analyzed regularly also did analze today as well,
> Below is the test case where I tried to use the partition key in join,
> but still getting the same result.
>
>
> explain select * from dm_ci360.page_details pd left join
> dm_ci360.page_details_ext pde on (pd.detail_id = pde.detail_id and
> *pd.client_id = pde.client_id*); -- "QUERY PLAN" Gather
> (cost=1328436468.62..1375694672.28 rows=421291719 width=8287) Workers
> Planned: 8 -> Merge Left Join (cost=1328435468.62..1333564500.38
> rows=52661465 width=8287) Merge Cond: (((pd.detail_id)::text =
> (pde.detail_id)::text) AND (pd.client_id = pde.client_id)) -> Sort
> (cost=1045342980.27..1045489637.23 rows=58662783 width=8061) " Sort Key:
> pd.detail_id, pd.client_id" -> Append (cost=0.00..24208020.84
> rows=58662783 width=8061) -> Parallel Seq Scan on page_details_null pd
> (cost=0.00..2425406.85 rows=5120384 width=8220) -> Parallel Seq Scan on
> page_details_m3 pd_1 (cost=0.00..503325.67 rows=1484767 width=8216) ->
> Parallel Seq Scan on page_details_m2 pd_2 (cost=0.00..41493.07 rows=158208
> width=8253) -> Parallel Seq Scan on page_details_m1 pd_3
> (cost=0.00..298542.32 rows=718532 width=8281) -> Parallel Seq Scan on
> page_details_5 pd_4 (cost=0.00..4546231.40 rows=9936540 width=8202) ->
> Parallel Seq Scan on page_details_31 pd_5 (cost=0.00..5351785.68
> rows=13473668 width=7721) -> Parallel Seq Scan on page_details_49 pd_6
> (cost=0.00..1528222.35 rows=3763935 width=7721) -> Parallel Seq Scan on
> page_details_52 pd_7 (cost=0.00..1005739.96 rows=2113496 width=8297) ->
> Parallel Seq Scan on page_details_59 pd_8 (cost=0.00..2139754.44
> rows=4577244 width=8276) -> Parallel Seq Scan on page_details_60 pd_9
> (cost=0.00..316209.20 rows=846820 width=8263) -> Parallel Seq Scan on
> page_details_61 pd_10 (cost=0.00..14790.59 rows=85759 width=8182) ->
> Parallel Seq Scan on page_details_63 pd_11 (cost=0.00..52206.08
> rows=204008 width=8250) -> Parallel Seq Scan on page_details_64 pd_12
> (cost=0.00..358858.43 rows=904143 width=8314) -> Parallel Seq Scan on
> page_details_66 pd_13 (cost=0.00..8647.65 rows=50365 width=8277) ->
> Parallel Seq Scan on page_details_67 pd_14 (cost=0.00..8507.65 rows=54465
> width=8227) -> Parallel Seq Scan on page_details_68 pd_15
> (cost=0.00..7667.92 rows=47192 width=8259) -> Parallel Seq Scan on
> page_details_78 pd_16 (cost=0.00..227673.87 rows=698287 width=8263) ->
> Parallel Seq Scan on page_details_98 pd_17 (cost=0.00..342905.89
> rows=975589 width=8225) -> Parallel Seq Scan on page_details_101 pd_18
> (cost=0.00..277631.48 rows=815948 width=8205) -> Parallel Seq Scan on
> page_details_130 pd_19 (cost=0.00..489453.45 rows=1409344 width=8199) ->
> Parallel Seq Scan on page_details_m100 pd_20 (cost=0.00..8943.50
> rows=62750 width=8225) -> Parallel Seq Scan on page_details_m4 pd_21
> (cost=0.00..119599.55 rows=409355 width=8195) -> Parallel Seq Scan on
> page_details_134 pd_22 (cost=0.00..1078678.24 rows=2791724 width=8176) ->
> Parallel Seq Scan on page_details_58 pd_23 (cost=0.00..19107.17
> rows=114617 width=8362) -> Parallel Seq Scan on page_details_69 pd_24
> (cost=0.00..11774.27 rows=56027 width=8268) -> Parallel Seq Scan on
> page_details_100 pd_25 (cost=0.00..14765.61 rows=83161 width=8195) ->
> Parallel Seq Scan on page_details_114 pd_26 (cost=0.00..17953.55
> rows=112155 width=8183) -> Parallel Seq Scan on page_details_m5 pd_27
> (cost=0.00..2069930.14 rows=4803014 width=8225) -> Parallel Seq Scan on
> page_details_32 pd_28 (cost=0.00..9655.67 rows=90767 width=8807) ->
> Parallel Seq Scan on page_details_23 pd_29 (cost=0.00..1183.66 rows=14966
> width=9327) -> Parallel Seq Scan on page_details_m6 pd_30
> (cost=0.00..331066.68 rows=766068 width=7814) -> Parallel Seq Scan on
> page_details_m7 pd_31 (cost=0.00..276835.86 rows=820386 width=8203) ->
> Parallel Seq Scan on page_details_m8 pd_32 (cost=0.00..219677.99
> rows=764299 width=8200) -> Parallel Seq Scan on page_details_144 pd_33
> (cost=0.00..1243.71 rows=10671 width=8189) -> Parallel Seq Scan on
> page_details_143 pd_34 (cost=0.00..79279.91 rows=304892 width=8196) ->
> Parallel Seq Scan on page_details_145 pd_35 (cost=0.00..3271.37 rows=19237
> width=8226) -> Materialize (cost=283092488.35..285385333.09 rows=458568949
> width=226) -> Sort (cost=283092488.35..284238910.72 rows=458568949
> width=226) " Sort Key: pde.detail_id, pde.client_id" -> Append
> (cost=0.00..16497547.49 rows=458568949 width=226) -> Seq Scan on
> page_details_ext_null pde (cost=0.00..1524481.42 rows=42223842 width=226)
> -> Seq Scan on page_details_ext_m3 pde_1 (cost=0.00..347731.78
> rows=9980078 width=226) -> Seq Scan on page_details_ext_m2 pde_2
> (cost=0.00..26437.83 rows=721783 width=226) -> Seq Scan on
> page_details_ext_m1 pde_3 (cost=0.00..180092.12 rows=4793812 width=226) ->
> Seq Scan on page_details_ext_5 pde_4 (cost=0.00..3157905.57 rows=84945757
> width=226) -> Seq Scan on page_details_ext_31 pde_5 (cost=0.00..4198600.83
> rows=125384283 width=226) -> Seq Scan on page_details_ext_49 pde_6
> (cost=0.00..1058695.45 rows=29083145 width=226) -> Seq Scan on
> page_details_ext_52 pde_7 (cost=0.00..582580.50 rows=16175450 width=226)
> -> Seq Scan on page_details_ext_59 pde_8 (cost=0.00..1276447.65
> rows=34184965 width=226) -> Seq Scan on page_details_ext_60 pde_9
> (cost=0.00..209865.67 rows=5987267 width=226) -> Seq Scan on
> page_details_ext_61 pde_10 (cost=0.00..10846.58 rows=301558 width=226) ->
> Seq Scan on page_details_ext_63 pde_11 (cost=0.00..32991.51 rows=897951
> width=226) -> Seq Scan on page_details_ext_64 pde_12 (cost=0.00..211218.56
> rows=6212356 width=226) -> Seq Scan on page_details_ext_66 pde_13
> (cost=0.00..4888.06 rows=127506 width=226) -> Seq Scan on
> page_details_ext_67 pde_14 (cost=0.00..5320.29 rows=139829 width=226) ->
> Seq Scan on page_details_ext_68 pde_15 (cost=0.00..4519.19 rows=121219
> width=226) -> Seq Scan on page_details_ext_78 pde_16 (cost=0.00..138728.11
> rows=3774711 width=226) -> Seq Scan on page_details_ext_98 pde_17
> (cost=0.00..235653.77 rows=6628477 width=226) -> Seq Scan on
> page_details_ext_101 pde_18 (cost=0.00..195898.44 rows=5365744 width=226)
> -> Seq Scan on page_details_ext_130 pde_19 (cost=0.00..327932.65
> rows=8781965 width=226) -> Seq Scan on page_details_ext_m100 pde_20
> (cost=0.00..4913.38 rows=143438 width=226) -> Seq Scan on
> page_details_ext_m4 pde_21 (cost=0.00..79001.77 rows=2065777 width=226) ->
> Seq Scan on page_details_ext_134 pde_22 (cost=0.00..757767.21
> rows=19952321 width=226) -> Seq Scan on page_details_ext_58 pde_23
> (cost=0.00..12171.64 rows=361364 width=331) -> Seq Scan on
> page_details_ext_69 pde_24 (cost=0.00..6617.58 rows=176558 width=226) ->
> Seq Scan on page_details_ext_100 pde_25 (cost=0.00..9531.93 rows=261993
> width=226) -> Seq Scan on page_details_ext_114 pde_26 (cost=0.00..11702.72
> rows=358372 width=226) -> Seq Scan on page_details_ext_m5 pde_27
> (cost=0.00..1300373.49 rows=33923749 width=226) -> Seq Scan on
> page_details_ext_23 pde_28 (cost=0.00..819.39 rows=25239 width=378) -> Seq
> Scan on page_details_ext_32 pde_29 (cost=0.00..7009.04 rows=217504
> width=378) -> Seq Scan on page_details_ext_m6 pde_30 (cost=0.00..181575.92
> rows=4720692 width=226) -> Seq Scan on page_details_ext_m7 pde_31
> (cost=0.00..196632.54 rows=5332554 width=226) -> Seq Scan on
> page_details_ext_m8 pde_32 (cost=0.00..142816.57 rows=3877857 width=226)
> -> Seq Scan on page_details_ext_144 pde_33 (cost=0.00..780.22 rows=18422
> width=226) -> Seq Scan on page_details_ext_143 pde_34 (cost=0.00..53050.54
> rows=1255354 width=226) -> Seq Scan on page_details_ext_145 pde_35
> (cost=0.00..1947.57 rows=46057 width=226)
>
>
> Thanks
>
> On Mon, Aug 16, 2021 at 9:47 AM Ron <ronljohnsonjr(at)gmail(dot)com
> <mailto:ronljohnsonjr(at)gmail(dot)com>> wrote:
>
> When were the tables last analyzed?
>
> Also, the whole set of partitions must be scanned, since the tables
> are partitioned by a field other than what's in the JOIN and WHERE
> clauses.
>
> On 8/13/21 7:23 AM, Shrikant Bhende wrote:
>>
>> We have two tables, both have ~36 partitions.
>> This is my first query, which attempts to join the parent tables on
>> the columns that have been used to create multi-column indexes for
>> all partitions (multi-column indexes defined on session_id, detail_id
>> in that order):
>>
>> *PostgreSQL version : 10
>> *-- *query*
>>
>> explain
>>
>> select * from dm_ci360.page_details pd
>> inner join dm_ci360.page_details_ext pde
>>  on (pd.session_id = pde.session_id
>>  and pd.detail_id = pde.detail_id)
>> where pd.session_dt >= now()::date-2;
>>
>> -- *plan*
>>
>> Hash Join  (cost=36927955.75..100106605.07 rows=11 width=8355)
>>
>>   Hash Cond: (((pd.session_id)::text = (pde.session_id)::text) AND
>> ((pd.detail_id)::text = (pde.detail_id)::text))
>>
>>   ->  Append  (cost=1297.33..571870.20 rows=630535 width=8130)
>>
>>         ->  Bitmap Heap Scan on page_details_null pd
>>  (cost=1297.33..240207.85 rows=69259 width=8220)
>>
>>               Recheck Cond: (session_dt >= ((now())::date - 2))
>>
>>               ->  Bitmap Index Scan on
>> page_details_null_session_dt_idx  (cost=0.00..1280.02 rows=69259 width=0)
>>
>>                     Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m3_session_dt_idx on
>> page_details_m3 pd_1  (cost=0.44..4.71 rows=1 width=8216)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m2_session_dt_idx on
>> page_details_m2 pd_2  (cost=0.43..102.79 rows=621 width=8253)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m1_session_dt_idx on
>> page_details_m1 pd_3  (cost=0.44..4.55 rows=1 width=8281)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_5_session_dt_idx on
>> page_details_5 pd_4  (cost=0.57..51622.53 rows=196574 width=8202)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Bitmap Heap Scan on page_details_31 pd_5
>>  (cost=982.61..194857.98 rows=52391 width=7721)
>>
>>               Recheck Cond: (session_dt >= ((now())::date - 2))
>>
>>               ->  Bitmap Index Scan on
>> page_details_31_session_dt_idx1  (cost=0.00..969.51 rows=52391 width=0)
>>
>>                     Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_49_session_dt_idx on
>> page_details_49 pd_6  (cost=0.45..10991.08 rows=50039 width=7721)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_52_session_dt_idx on
>> page_details_52 pd_7  (cost=0.44..2337.94 rows=10222 width=8297)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_59_session_dt_idx on
>> page_details_59 pd_8  (cost=0.57..24790.17 rows=50148 width=8276)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_60_session_dt_idx on
>> page_details_60 pd_9  (cost=0.44..7292.41 rows=4259 width=8263)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_61_session_dt_idx on
>> page_details_61 pd_10  (cost=0.43..309.10 rows=704 width=8182)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_63_session_dt_idx on
>> page_details_63 pd_11  (cost=0.43..13.20 rows=25 width=8250)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_64_session_dt_idx on
>> page_details_64 pd_12  (cost=0.44..5.41 rows=1 width=8314)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_66_session_dt_idx on
>> page_details_66 pd_13  (cost=0.42..4.49 rows=1 width=8277)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_67_session_dt_idx on
>> page_details_67 pd_14  (cost=0.42..58.62 rows=325 width=8227)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_68_session_dt_idx on
>> page_details_68 pd_15  (cost=0.42..35.20 rows=111 width=8259)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_78_session_dt_idx on
>> page_details_78 pd_16  (cost=0.44..1738.10 rows=4608 width=8263)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_98_session_dt_idx on
>> page_details_98 pd_17  (cost=0.44..2157.31 rows=7136 width=8225)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_101_session_dt_idx on
>> page_details_101 pd_18  (cost=0.44..2956.03 rows=9241 width=8205)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_130_session_dt_idx on
>> page_details_130 pd_19  (cost=0.44..1683.53 rows=19656 width=8199)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m100_session_dt_idx on
>> page_details_m100 pd_20  (cost=0.43..4.96 rows=1 width=8225)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m4_session_dt_idx on
>> page_details_m4 pd_21  (cost=0.43..659.89 rows=6097 width=8195)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_134_session_dt_idx on
>> page_details_134 pd_22  (cost=0.45..4666.25 rows=50409 width=8176)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_58_session_dt_idx on
>> page_details_58 pd_23  (cost=0.43..7.05 rows=1 width=8362)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_69_session_dt_idx on
>> page_details_69 pd_24  (cost=0.43..125.03 rows=348 width=8268)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_100_session_dt_idx on
>> page_details_100 pd_25  (cost=0.43..381.13 rows=466 width=8195)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_114_session_dt_idx on
>> page_details_114 pd_26  (cost=0.43..7.80 rows=1 width=8183)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m5_session_dt_idx on
>> page_details_m5 pd_27  (cost=0.57..4505.18 rows=50872 width=8225)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_32_session_dt_idx on
>> page_details_32 pd_28  (cost=0.43..8.44 rows=1 width=8807)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_23_session_dt_idx on
>> page_details_23 pd_29  (cost=0.29..7.47 rows=1 width=9327)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m6_session_dt_idx on
>> page_details_m6 pd_30  (cost=0.44..769.32 rows=7135 width=7814)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m7_session_dt_idx on
>> page_details_m7 pd_31  (cost=0.44..11400.50 rows=14694 width=8203)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_m8_session_dt_idx on
>> page_details_m8 pd_32  (cost=0.44..6568.86 rows=8045 width=8200)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_144_session_dt_idx on
>> page_details_144 pd_33  (cost=0.29..21.16 rows=162 width=8189)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_143_session_dt_idx on
>> page_details_143 pd_34  (cost=0.43..1477.00 rows=16135 width=8197)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>         ->  Index Scan using page_details_145_session_dt_idx on
>> page_details_145 pd_35  (cost=0.29..87.17 rows=844 width=8226)
>>
>>               Index Cond: (session_dt >= ((now())::date - 2))
>>
>>   ->  Hash  (cost=16117516.77..16117516.77 rows=449927377 width=226)
>>
>>         ->  Append  (cost=0.00..16117516.77 rows=449927377 width=226)
>>
>>               ->  Seq Scan on page_details_ext_null pde
>>  (cost=0.00..1467668.52 rows=40845752 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m3 pde_1
>>  (cost=0.00..347732.32 rows=9980132 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m2 pde_2
>>  (cost=0.00..26146.27 rows=715527 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m1 pde_3
>>  (cost=0.00..180093.08 rows=4793908 width=226)
>>
>>               ->  Seq Scan on page_details_ext_5 pde_4
>>  (cost=0.00..3056150.08 rows=82652608 width=226)
>>
>>               ->  Seq Scan on page_details_ext_31 pde_5
>>  (cost=0.00..4177416.08 rows=124953208 width=226)
>>
>>               ->  Seq Scan on page_details_ext_49 pde_6
>>  (cost=0.00..1034364.84 rows=28538484 width=226)
>>
>>               ->  Seq Scan on page_details_ext_52 pde_7
>>  (cost=0.00..575529.72 rows=16018272 width=226)
>>
>>               ->  Seq Scan on page_details_ext_59 pde_8
>>  (cost=0.00..1226617.78 rows=33054378 width=226)
>>
>>               ->  Seq Scan on page_details_ext_60 pde_9
>>  (cost=0.00..206925.60 rows=5920260 width=226)
>>
>>               ->  Seq Scan on page_details_ext_61 pde_10
>>  (cost=0.00..10599.63 rows=296463 width=226)
>>
>>               ->  Seq Scan on page_details_ext_63 pde_11
>>  (cost=0.00..32993.45 rows=898145 width=226)
>>
>>               ->  Seq Scan on page_details_ext_64 pde_12
>>  (cost=0.00..211220.00 rows=6212500 width=226)
>>
>>               ->  Seq Scan on page_details_ext_66 pde_13
>>  (cost=0.00..4888.44 rows=127544 width=226)
>>
>>               ->  Seq Scan on page_details_ext_67 pde_14
>>  (cost=0.00..5121.02 rows=135402 width=226)
>>
>>               ->  Seq Scan on page_details_ext_68 pde_15
>>  (cost=0.00..4284.18 rows=116218 width=226)
>>
>>               ->  Seq Scan on page_details_ext_78 pde_16
>>  (cost=0.00..135663.64 rows=3705564 width=226)
>>
>>               ->  Seq Scan on page_details_ext_98 pde_17
>>  (cost=0.00..232421.44 rows=6556944 width=226)
>>
>>               ->  Seq Scan on page_details_ext_101 pde_18
>>  (cost=0.00..189844.81 rows=5231481 width=226)
>>
>>               ->  Seq Scan on page_details_ext_130 pde_19
>>  (cost=0.00..318011.40 rows=8558640 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m100 pde_20
>>  (cost=0.00..4914.04 rows=143504 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m4 pde_21
>>  (cost=0.00..75878.68 rows=1994468 width=226)
>>
>>               ->  Seq Scan on page_details_ext_134 pde_22
>>  (cost=0.00..724264.36 rows=19192136 width=226)
>>
>>               ->  Seq Scan on page_details_ext_58 pde_23
>>  (cost=0.00..12171.94 rows=361394 width=331)
>>
>>               ->  Seq Scan on page_details_ext_69 pde_24
>>  (cost=0.00..6464.95 rows=173295 width=226)
>>
>>               ->  Seq Scan on page_details_ext_100 pde_25
>>  (cost=0.00..9217.39 rows=255239 width=226)
>>
>>               ->  Seq Scan on page_details_ext_114 pde_26
>>  (cost=0.00..11702.69 rows=358469 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m5 pde_27
>>  (cost=0.00..1274434.84 rows=33330284 width=226)
>>
>>               ->  Seq Scan on page_details_ext_23 pde_28
>>  (cost=0.00..822.03 rows=25503 width=378)
>>
>>               ->  Seq Scan on page_details_ext_32 pde_29
>>  (cost=0.00..7011.56 rows=217756 width=378)
>>
>>               ->  Seq Scan on page_details_ext_m6 pde_30
>>  (cost=0.00..177039.58 rows=4616658 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m7 pde_31
>>  (cost=0.00..188264.43 rows=5143643 width=226)
>>
>>               ->  Seq Scan on page_details_ext_m8 pde_32
>>  (cost=0.00..139185.56 rows=3799056 width=226)
>>
>>               ->  Seq Scan on page_details_ext_144 pde_33
>>  (cost=0.00..687.46 rows=16246 width=226)
>>
>>               ->  Seq Scan on page_details_ext_143 pde_34
>>  (cost=0.00..41053.82 rows=971482 width=226)
>>
>>               ->  Seq Scan on page_details_ext_145 pde_35
>>  (cost=0.00..711.14 rows=16814 width=226)
>>
>>
>>
>> The only place an index scan is used is to filter down page_details.
>> In my second query,
>> when explicitly joining single partitions an index scan is used to
>> perform filtering, and the join as well:
>>
>> --*query*
>>
>> explain
>>
>> select * from dm_ci360.page_details_5 pd
>> inner join dm_ci360.page_details_ext_5 pde
>> on (pd.session_id = pde.session_id
>> and pd.detail_id = pde.detail_id)
>> where pd.session_dt >= now()::date-2;
>>
>>
>> --*plan*
>>
>> Nested Loop  (cost=1.27..1685980.38 rows=1 width=8428)
>>
>>   ->  Index Scan using page_details_5_session_dt_idx on
>> page_details_5 pd  (cost=0.57..51267.67 rows=196574 width=8202)
>>
>>         Index Cond: (session_dt >= ((now())::date - 2))
>>
>>   ->  Index Scan using page_details_ext_5_session_id_detail_id_idx on
>> page_details_ext_5 pde  (cost=0.69..8.31 rows=1 width=226)
>>
>>         Index Cond: (((session_id)::text = (pd.session_id)::text) AND
>> ((detail_id)::text = (pd.detail_id)::text))
>>
>> I just cannot figure out why the join for the parent table will not
>> leverage the index,
>> but the join for a single partition will. We are running on Postgres
>> 10, and the row counts for the tables can be found below:
>>
>> *Row Count*
>> page_details -> ~413M
>> page_details_ext -> ~450M
>>
>> *Table DDL*
>> *
>> *
>> |-- page_details CREATE TABLE dm_ci360.page_details ( dml_id int4
>> NULL, dml_ts timestamp NULL, dml_ts_utc timestamp NULL, dml_type
>> varchar(1) NULL, dwh_job_id int4 NULL, ins_dwh_job_id int4 NULL,
>> upd_dwh_job_id int4 NULL, deleted_flag varchar(1) NULL,
>> processed_dttm timestamp NULL, valid_from_dttm timestamp(0) NULL,
>> valid_to_dttm timestamp(0) NULL, ccd varchar(2000) NULL, client_id
>> int4 NULL, detail_id varchar(32) NULL, session_id varchar(29) NULL,
>> visit_id varchar(32) NULL, window_size_txt varchar(20) NULL,
>> session_dt date NULL, page_url_txt varchar(1332) NULL, domain_nm
>> varchar(165) NULL, bytes_sent_cnt int4 NULL, page_load_sec_cnt int8
>> NULL, page_complete_sec_cnt int8 NULL, protocol_nm varchar(8) NULL,
>> page_desc varchar(1332) NULL, class1_id varchar(650) NULL, class2_id
>> varchar(650) NULL, class3_id varchar(650) NULL, class4_id
>> varchar(650) NULL, class5_id varchar(650) NULL, class6_id
>> varchar(650) NULL, class7_id varchar(650) NULL, class8_id
>> varchar(650) NULL, class9_id varchar(650) NULL, class10_id
>> varchar(650) NULL, class11_id varchar(650) NULL, class12_id
>> varchar(650) NULL, class13_id varchar(650) NULL, class14_id
>> varchar(650) NULL, class15_id varchar(650) NULL, url_domain
>> varchar(215) NULL, identity_id varchar(36) NULL, detail_dttm
>> timestamp NULL, detail_dttm_tz timestamp NULL, load_dttm timestamp
>> NULL, session_dt_tz date NULL, detail_id_hex varchar(32) NULL,
>> visit_id_hex varchar(32) NULL, session_id_hex varchar(29) NULL )
>> PARTITION BY LIST (client_id); CREATE TABLE dm_ci360.page_details_100
>> PARTITION OF dm_ci360.page_details FOR VALUES IN (100); CREATE INDEX
>> page_details_100_detail_dttm_idx ON dm_ci360.page_details_100 USING
>> btree (detail_dttm) CREATE INDEX page_details_100_identity_id_idx ON
>> dm_ci360.page_details_100 USING btree (identity_id) CREATE INDEX
>> page_details_100_session_dt_idx ON dm_ci360.page_details_100 USING
>> btree (session_dt) CREATE INDEX
>> page_details_100_session_id_detail_id_idx ON
>> dm_ci360.page_details_100 USING btree (session_id, detail_id) --
>> page_details_ext CREATE TABLE dm_ci360.page_details_ext ( dml_id int4
>> NULL, dml_ts timestamp NULL, dml_ts_utc timestamp NULL, dml_type
>> varchar(1) NULL, dwh_job_id int4 NULL, ins_dwh_job_id int4 NULL,
>> upd_dwh_job_id int4 NULL, deleted_flag varchar(1) NULL,
>> processed_dttm timestamp NULL, valid_from_dttm timestamp(0) NULL,
>> valid_to_dttm timestamp(0) NULL, ccd varchar(2000) NULL, client_id
>> int4 NULL, detail_id varchar(32) NULL, session_id varchar(29) NULL,
>> active_sec_spent_on_page_cnt int4 NULL, seconds_spent_on_page_cnt
>> int4 NULL, load_dttm timestamp NULL, detail_id_hex varchar(32) NULL,
>> session_id_hex varchar(29) NULL ) PARTITION BY LIST (client_id);
>> CREATE TABLE dm_ci360.page_details_ext_100 PARTITION OF
>> dm_ci360.page_details_ext FOR VALUES IN (100); CREATE INDEX
>> page_details_ext_100_session_id_detail_id_idx ON
>> dm_ci360.page_details_ext_100 USING btree (session_id, detail_id)|
>> CREATE INDEX page_details_ext_100_session_id_detail_id_idx ON
>> dm_ci360.page_details_ext_100 USING btree (session_id, detail_id)
>> Thanks
>
> --
> Angular momentum makes the world go 'round.
>

--
Angular momentum makes the world go 'round.