Hello,

Yes, you are right; it seems that only 4 batches had data changes. However, the query also accessed other batches and then removed them again. What could be the reason for this and how can it be solved?

Obviously, I would like to understand this situation better and learn the solution.

I would be very grateful if you could help me.

Thank you,

Eşref Halıcıoğlu

----------------

To: Eşref Halıcıoğlu (esref.halicioglu@primeit.com.tr);

Cc: pgsql-general@lists.postgresql.org;

Subject: About PostgreSQL Query Plan;

13.01.2025, 19:56, "hubert depesz lubaczewski" <depesz@depesz.com>:

On Mon, Jan 13, 2025 at 07:48:09PM +0300, Eşref Halıcıoğlu wrote:
Hello,

Yes, you are right; this query is not a SELECT, it is an UPDATE query, there was a mistake in expressing it here. The columns I want
to update here only operate on data from the last 3 months time interval.

I am also sharing the EXPLAIN ANALYZE output of the relevant query below:

Update on "TestTable1" t1 (cost=0.13..159114.84 rows=0 width=0) (actual time=0.007..0.008 rows=0 loops=1)
   Update on "PartitionTable_2020_10" t1
… 61 lines removed …
   Update on "PartitionTable_2025_12" t1
   Update on "DefaultPartitionTable" t1
   -> Nested Loop (cost=0.13..159114.84 rows=1 width=53) (actual time=0.006..0.006 rows=0 loops=1)
         -> Seq Scan on "TempTable1" tmp (cost=0.00..19.20 rows=920 width=31) (actual time=0.006..0.006 rows=0 loops=1)
         -> Append (cost=0.13..172.29 rows=64 width=38) (never executed)
               Subplans Removed: 60
               -> Index Scan using partitiontable_2024_10_pkey on "PartitionTable_2024_10" t2 (cost=0.43..4.21 rows=1 width=38) (never executed)
                     Index Cond: (("Col1" = tmp."Col2") AND ("Col3" >= (CURRENT_DATE - '3 mons'::interval)) AND ("Col3" <= CURRENT_DATE))
                     Filter: ((NOT "IsDeleted") AND ("Col4" = tmp."Col5"))
               -> Index Scan using partitiontable_2024_11_pkey on "PartitionTable_2024_11" t3 (cost=0.43..4.23 rows=1 width=38) (never executed)
                     Index Cond: (("Col1" = tmp."Col2") AND ("Col3" >= (CURRENT_DATE - '3 mons'::interval)) AND ("Col3" <= CURRENT_DATE))
                     Filter: ((NOT "IsDeleted") AND ("Col4" = tmp."Col5"))
               -> Index Scan using partitiontable_2024_12_pkey on "PartitionTable_2024_12" t4 (cost=0.43..4.34 rows=1 width=38) (never executed)
                     Index Cond: (("Col1" = tmp."Col2") AND ("Col3" >= (CURRENT_DATE - '3 mons'::interval)) AND ("Col3" <= CURRENT_DATE))
                     Filter: ((NOT "IsDeleted") AND ("Col4" = tmp."Col5"))
               -> Index Scan using partitiontable_2025_01_pkey on "PartitionTable_2025_01" t5 (cost=0.43..3.72 rows=1 width=38) (never executed)
                     Index Cond: (("Col1" = tmp."Col2") AND ("Col3" >= (CURRENT_DATE - '3 mons'::interval)) AND ("Col3" <= CURRENT_DATE))
                     Filter: ((NOT "IsDeleted") AND ("Col4" = tmp."Col5"))
Planning Time: 3.860 ms
Execution Time: 0.066 ms

Well, it helped, and I missed some bits of information earlier.
Generally it looks that it was trying to scan only 4 partitions, but
they all got skipped.

Best regards,

depesz