kevin kempter wrote:
Hi List;
I have a table with 9,961,914 rows in it (see the describe of
bigtab_stats_fact_tmp14 below)
I also have a table with 7,785 rows in it (see the describe of
xsegment_dim below)
Something else is puzzling me with this - you're joining over four fields.
from
bigtab_stats_fact_tmp14 f14,
xsegment_dim segdim
where
f14.customer_id = segdim.customer_srcid
and f14.show_id = segdim.show_srcid
and f14.season_id = segdim.season_srcid
and f14.episode_id = segdim.episode_srcid
and segdim.segment_srcid is NULL;
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Merge Join (cost=1757001.74..73569676.49 rows=3191677219 width=118)
-> Sort (cost=1570.35..1579.46 rows=3643 width=40)
-> Sort (cost=1755323.26..1780227.95 rows=9961874 width=126)
Here it's still expecting 320 matches against each row from the large
table. That's ~ 10% of the small table (or that fraction of it that PG
expects) which seems very high for four clauses ANDed together.
--
Richard Huxton
Archonet Ltd
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